A synergistic, global approach to revising the trypanorhynch tapeworm family Rhinoptericolidae (Trypanobatoida)

Introduction

The monotypic family Rhinoptericolidae Carvajal & Campbell, 1975 was erected to accommodate the genus Rhinoptericola Carvajal & Campbell, 1975 and its type species, Rhinoptericola megacantha Carvajal & Campbell, 1975. Since then, the family has been synonymized, resurrected, moved between three superfamilies, and has variously included members of several unusual trypanorhynch genera. In light of the significant changes proposed in this study to the species diversity, degree of host specificity, interrelationships, and the interpretation of the tentacular armature of the family as a whole or its members, a summary of its convoluted history is warranted.

Carvajal & Campbell (1975) described R. megacantha based on worms from a single adult American cownose ray, Rhinoptera bonasus (Mitchill, 1815), collected from the Chesapeake Bay, Virginia, USA, as possessing a heteroacanthous atypical metabasal armature (i.e., an armature with hooks arranged in paired principal rows with one or more intercalary hook[s] between those rows). The authors distinguished the new species from the other heteroacanthous atypical trypanorhynchs known at the time (species in the families Otobothriidae Dollfus, 1942 and Mustelicolidae Dollfus, 1969) based on its unique morphology: possession of four bothria and a uterus bifurcated at the posterior end, and lack of bothrial pits. They thus justified the creation of a new family. In addition to describing R. megacantha as an atypical heteroacanth, the authors (mistakenly) reported that the species lacks prebulbar organs and made no mention of gland cells in the bulbs.

Nearly two decades later, Campbell & Beveridge (1994) formally allied the Rhinoptericolidae with the other families of heteroacanthous atypical trypanorhynchs, placing them together in the superfamily Otobothrioidea Dollfus, 1942. Shortly thereafter, Palm (1995, 1997) published a revised classification for the trypanorhynchs which emphasized morphological features other than tentacular armature. In the classification of Palm (1997), Rhinoptericola was moved to the family Pterobothriidae Pintner, 1931 within the superfamily Tentacularioidea Poche, 1926 based on its reported lack of bothrial pits and prebulbar organs, and its possession of four bothria and a heteroacanthous atypical metabasal armature, thus making Rhinoptericolidae a junior synonym of Pterobothriidae.

In the first cladistic analysis for the trypanorhynchs, based on 44 morphological characters coded for 49 genera, Beveridge, Campbell & Palm (1999) recovered Rhinoptericola in a clade with members of the families Shirleyrhynchidae Campbell & Beveridge, 1994 and Mixodigmatidae Dailey & Vogelbein, 1982, a group the authors referred to as “Clade 5”. As they did not recover Rhinoptericola allied with the otobothriids or pterobothriids, Beveridge, Campbell & Palm (1999) rejected the classifications of Campbell & Beveridge (1994) and Palm (1997) and resurrected the Rhinoptericolidae from synonymy. They also noted that the families in their Clade 5 share morphological features with the family Eutetrarhynchidae Guiart, 1927, members of which form a sister group to Clade 5 in their analysis. Though this comparison was made, the authors maintained in their discussion that R. megacantha lacked prebulbar organs (a feature shared by all eutetrarhynchids). Superfamilial placements were not discussed for any taxa in this analysis.

In his formative opus on the order Trypanorhyncha, Palm (2004) made Shirleyrhynchidae a junior synonym of Rhinoptericolidae, reclassifying both shirleyrhynchid genera (i.e., Shirleyrhynchus Beveridge & Campbell, 1988 and Cetorhinicola Beveridge & Campbell, 1988) as rhinoptericolids. He also moved the Rhinoptericolidae—at that time containing, for the first time since its creation, three genera—to the superfamily Eutetrarhynchoidea Guiart, 1927. In his revised familial diagnosis, Palm (2004) specified a heteroacanthous typical metabasal armature for the rhinoptericolids. Both Shirleyrhynchus and Cetorhinicola were originally described as typical heteroacanths (see Beveridge & Campbell, 1988), but unlike the former shirleyrhynchids, Rhinoptericola was described as possessing intercalary hooks (Carvajal & Campbell, 1975). Palm (2004) did not mention this significant change for Rhinoptericola in his discussion of the newly circumscribed Rhinoptericolidae, except to say that the possession of a heteroacanthous typical armature was a feature that unified the three genera. Furthermore, he did not mention the presence or absence of prebulbar organs in Rhinoptericola even though he had, for the first time, classified the Rhinoptericolidae as belonging to a superfamily for which morphological synapomorphies include the presence of prebulbar organs.

To piece together the complete picture of the redefinition of the Rhinoptericolidae by Palm (2004), one must read his discussion sections for Rhinoptericola and R. megacantha. It is in these sections where Palm reported that a reexamination of type material of R. megacantha revealed the lack of intercalary hooks and the presence of prebulbar organs, thus justifying his earlier taxonomic and systematic changes at the family level. He did not, however, provide any description, photograph, or illustration to demonstrate how the hooks of R. megacantha which were originally described by Carvajal & Campbell (1975) as intercalary hooks could be reinterpreted as belonging to principal rows, or to demonstrate the presence of prebulbar organs in this species.

Palm et al. (2009) produced the first phylogenetic hypothesis for the order Trypanorhyncha based on molecular sequence data (18S rRNA and partial 28S rRNA). They included one specimen each of R. megacantha and Nataliella marcelli Palm, 2010 (as “Unidentified gen. nov. sp. nov. [Hp 47, pl]”), as well as a specimen identified therein as Shirleyrhynchus aetobatidis (Shipley & Hornell, 1906) Beveridge & Campbell, 1998. In that analysis, R. megacantha was recovered as the sister taxon to a clade containing N. marcelli + the Tentaculariidae Poche, 1926, while the specimen identified as S. aetobatidis was recovered deeply embedded within a clade of eutetrarhychid taxa, thus rendering the Rhinoptericolidae of Palm (2004) paraphyletic. Olson et al. (2010) later published an alternative hypothesis, also based on 18S rRNA and partial 28S rRNA, but their analysis included only R. megacantha (recovered as sister to the tentaculariids) and the specimen identified as S. aetobatidis (similarly recovered embedded among eutetrarhynchids). In both analyses, a monophyletic Tentaculariidae were recovered embedded within the eutetrarhynchoids, resulting in a paraphyletic Eutetrarhynchoidea.

The next significant contribution to the taxonomic history of the Rhinoptericolidae was made by Palm (2010), wherein he resurrected the Shirleyrhynchidae to once again comprise the genera Shirleyrhynchus and Cetorhinicola, and formally described N. marcelli as a new genus and species belonging to the Rhinoptericolidae (now containing only Rhinoptericola and Nataliella Palm, 2010). The inclusion of N. marcelli in the Rhinoptericolidae necessitated revision of the familial diagnosis to accommodate its homeoacanthous metabasal armature. It is in this revised familial diagnosis that, for the first time, the family Rhinoptericolidae was explicitly defined by its members possessing the unique combination of four bothria, prebulbar organs, and a heteroacanthous typical (or homeoacanthous) metabasal armature, but lacking gland cells in the bulbs (Palm, 2010).

The removal of Shirleyrhynchus and Cetorhinicola from the Rhinoptericolidae was not explicitly justified by Palm (2010). Schaeffner (2016) speculated that the decision was perhaps based on an interpretation of the results of the molecular phylogenetic analyses of Palm et al. (2009) and Olson et al. (2010), in which the specimen identified as S. aetobatidis was recovered as deeply embedded among eutetrarhynchids. Schaeffner (2016) reexamined the hologenophore of this specimen and reidentified it as the eutetrarhynchid Parachristianella indonesiensis Palm, 2004. Thus, if Palm (2010) resurrected the Shirleyrhynchidae based on the results of these analyses, he was perhaps unknowingly misled by this misidentification.

Despite elucidating this specimen identification error and making extensive taxonomic revisions within the genus Shirleyrhynchus, Schaeffner (2016) refrained from making any change at the family level. In the most recent review of the order by Beveridge et al. (2017), the authors confirmed (Rhinoptericola + (Nataliella + Tentaculariidae)) of Palm et al. (2009) as the accepted relationship between those taxa and commented on the paraphyletic nature of the Rhinoptericolidae, but similarly refrained from making taxonomic or systematic changes. Thus, the classification of Palm (2010) (i.e., a Rhinoptericolidae inclusive of Rhinoptericola and Nataliella, and a Shirleyrhynchidae inclusive of Shirleyrhynchus and Cetorhinicola) had been accepted for the last decade prior to this study. Both Rhinoptericola and Nataliella have remained monotypic since their descriptions.

Findings from recent global elasmobranch collections once more call into question the identity of the Rhinoptericolidae, necessitating its revision. The status of the family also has implications for resolving the non-monophyly of other groups within the Trypanobatoida (see Beveridge et al., 2017). The goal of this study was to use the Rhinoptericolidae as a model for applying a novel, multi-pronged approach for stabilizing the taxonomy and classification of trypanorhynch tapeworms. The contributions of this study to trypanorhynch systematics include assessment of the validity of the Rhinoptericolidae, expansion of its membership via synonymy and the description of new species, redescriptions of its valid members, and expansion of the geographic range and known host species for the type species of Rhinoptericola, R. megacantha. The broader conceptual contributions of this work include a comprehensive assessment of generic and specific boundaries for species of trypanorhynchs based on sequence data, reinterpretations of tentacular armature facilitated by scanning electron microscopy (SEM) data, and the introduction of a visual tool to effectively communicate the tentacle surfaces depicted in line drawings and scanning electron micrographs (SEMs).

Materials and Methods

The electronic version of this article in Portable Document Format (PDF) will represent a published work according to the International Commission on Zoological Nomenclature (ICZN), and hence the new names contained in the electronic version are effectively published under that Code from the electronic edition alone. This published work and the nomenclatural acts it contains have been registered in ZooBank, the online registration system for the ICZN. The ZooBank LSIDs (Life Science Identifiers) can be resolved and the associated information viewed through any standard web browser by appending the LSID to the prefix http://zoobank.org/. The LSID for this publication is: urn:lsid:zoobank.org:pub:CE2287DE-C097-4EA5-84D4-7DC7E8F3BE7A. The online version of this work is archived and available from the following digital repositories: PeerJ, PubMed Central and CLOCKSS.

Specimen preparation and examination

Specimen preparation as whole mounts or vouchers for examination with light microscopy, as whole or partial specimens for examination with scanning electron microscopy (SEM), and for histological sectioning of specimens embedded in glycol methacrylate follows (Herzog & Jensen (2017) and Herzog & Jensen (2018). Generation of line drawings and photomicrographs of histological sections follows Herzog & Jensen (2018). Measurements were taken using INFINITY ANALYZE v.7.0.26.20 image analysis software (Teledyne Lumenera, Ottawa, ON, Canada). Measurements are reported in micrometers unless otherwise specified and are presented as ranges followed in parentheses by the mean, standard deviation, number of specimens measured, and total number of measurements taken if more than a single measurement was made per worm. Means were calculated as the sum of all measurements taken, divided by the total number of measurements taken, regardless of the number of measurements made per worm. Measurements of reproductive organs were made in mature terminal proglottids only unless otherwise specified. Only ranges are presented if four or fewer total measurements were taken. For redescriptions where the holotype was remeasured, measurement values for the holotype are given in brackets following each series of measurements.

Scolex length to width ratios were based on scolex total lengths and scolex maximum widths; scolex maximum widths were measured at the pars bothrialis or pars bulbosa, depending on the specimen. Visual representations of the terms used to describe hook measurements and the patterns shown beneath line drawings and scanning electron micrographs to describe tentacle surfaces are given in Fig. 1. Oncotaxy follows Campbell & Beveridge (1994). Microthrix terminology follows Chervy (2009). Shape terminology follows Clopton (2004). Museum abbreviations are as follows: Australian Helminthological Collection (AHC), South Australian Museum (SAM), Adelaide, South Australia, Australia; Colección Nacional de Helmintos (CNHE), Instituto de Biología, Universidad Nacional Autónoma de México, Mexico City, Mexico; H. W. Manter Laboratory of Parasitology (HWML), University of Nebraska, Lincoln, Nebraska, USA; Lawrence R. Penner Parasitology Collection (LRP), Department of Ecology and Evolutionary Biology, University of Connecticut, Storrs, Connecticut, USA; Laboratorio de Artrópodos Venenosos (LAV), Museo de Invertebrados G. B. Fairchild (MIUP), Universidad de Panama, Panama City, Panama; Museu de Zoologia Universidade de São Paulo (MZUSP), São Paulo, Brazil; Museum Zoologicum Bogoriense (MZB), Center for Biology, Indonesian Institute of Science, Cibinong, Jakarta-Bogor, Java, Indonesia; Muzium Zoologi (MZUM or MZUM[P]), Universiti Malaya, Kuala Lumpur, Malaysia; Naturhistorisches Museum Wien (VNHM; formerly NMV), Vienna, Austria; Queensland Museum (QM), Invertebrate Collection, Worms & Echinoderms Department, South Brisbane, Australia; Sarawak Biodiversity Center (SBC), Kuching, Sarawak, Malaysia; National Museum of Natural History (USNM; formerly USNPC), Smithsonian Institution, Washington, D. C., USA; Zoological Reference Collection (ZRC), Lee Kong Chian Natural History Museum, National University of Singapore, Singapore, Republic of Singapore.

Results

All reports of species of Rhinoptericola from the literature and this study are summarized in Table 3.

Taxonomic descriptions and redescriptions

Rhinoptericolidae Carvajal & Campbell, 1975

Synonym: Shirleyrhynchidae Campbell & Beveridge, 1994.

Type genus: Rhinoptericola Carvajal & Campbell, 1975 (syn. Shirleyrhynchus Beveridge & Campbell, 1988).

Other genera: Nataliella Palm, 2010.

Diagnosis (modified from Palm, 2010)

Scolex craspedote or acraspedote, elongate, slender. Bothria four in number, elliptoid, with free lateral and posterior margins, arranged in dorsal and ventral pairs, not overlapping pars bulbosa; bothrial pits absent. Pintner’s cells absent. Rhyncheal apparatus present. Tentacle sheaths sinuous. Prebulbar organs present. Bulbs long; gland cells in bulbs absent; retractor muscles originate at base of bulbs. Pars postbulbosa present or absent. Tentacles long, with slight basal swelling. Characteristic basal armature present; hooks heteromorphous, solid or hollow, arranged in quincunxes or indistinct rows; macrohooks present or absent; billhooks present or absent. Metabasal armature heteroacanthous typical heteromorphous or homeoacanthous homeomorphous; hooks solid or hollow, arranged in alternating ascending half-spiral rows with hook files 1 and (1′) separated, or arranged in quincunxes. Band of hooks, chainette elements and intercalary hooks absent.

Strobila apolytic or euapolytic. Proglottids acraspedote. Testes medullary, arranged in two columns in single layer essentially anterior to ovary. External and internal seminal vesicles absent. Cirrus unarmed. Genital atrium absent. Genital pores separate, unilateral, at or anterior to mid-level of proglottid; male and female genital pores at same level. Vagina medial in proglottid; vaginal sphincter absent; seminal receptacle present. Ovary terminal in proglottid, H-shaped in dorsoventral view, tetralobed in cross-section, with lobulated margins. Vitellarium follicular; follicles circumcortical, extending entire length of proglottid, interrupted dorsally and ventrally by ovary, partially interrupted ventrally by terminal genitalia. Uterus saccate, medial, dorsal to vagina, bifurcated at posterior end, extending from anterior margin of ovary to anterior margin of proglottid. Uterine pore present or absent. Excretory vessels four, arranged in one dorsal and one ventral pair on each lateral margin of proglottid. Eggs single, essentially spherical, non-embryonated; polar filaments absent. Plerocercus larval stage present, or larvae unknown. Parasites of Rhinopteridae Jordan & Evermann, 1896, and Dasyatidae Jordan, 1888 (Myliobatiformes), also in Aetobatidae White & Naylor, 2016, Potamotrygonidae Garman, 1877, and Urotrygonidae McEachran, Dunn & Miyake, 1996 (Myliobatiformes), and Hemiscylliidae Gill, 1862 (Orectolobiformes) as adults; parasites of Acanthuridae Bonaparte, 1832 (Acanthuriformes), Scombridae Rafinesque, 1815 (Scombriformes), and Lutjanidae Gill, 1861 and Priacanthidae Günther, 1859 (Perciformes) as larvae.

Remarks: The original diagnosis of the family Rhinoptericolidae by Carvajal & Campbell (1975) was revised thrice prior to this study (Campbell & Beveridge, 1994; Palm, 2004; Palm, 2010). The revised diagnosis herein is modified from the most recent diagnosis by Palm (2010). It incorporates the novel scolex morphologies represented by the new species described in this study, as well as clarifies and expands on the details of rhinoptericolid proglottid anatomy. As all rhinoptericolids described to date possess a characteristic basal armature, this feature is newly added to the familial diagnosis. The possession of solid or hollow hooks in the metabasal armature is also added to accommodate the morphology of a new species described herein. With respect to proglottid anatomy, the familial diagnosis of Palm (2010) was limited to the mention of pore position in the anterior third of the proglottid, and the presence of seminal vesicles. The diagnosis is expanded here significantly to include the description of a number of additional proglottid features. Deviating from Palm (2010), the family is now known to also include species with a genital pore at the mid-level of the proglottid, and external and internal seminal vesicles are considered to be absent in all species with known proglottid anatomies.

Shirleyrhynchidae is considered a junior synonym of Rhinoptericolidae, but Cetorhinicola acanthocapax Beveridge & Campbell, 1988 is not herein transferred to the Rhinoptericolidae. No specimens of C. acanthocapax preserved in 95% EtOH were available from which to generate sequence data. In the absence of molecular evidence, morphology alone is used to inform its higher-level associations. Though, like the rhinoptericolids, C. acanthocapax possesses prebulbar organs and four bothria, unlike rhinoptericolids, it possesses gland cells in the bulbs, laciniated proglottids, testes arranged in multiple columns, a genital atrium, a vagina strongly recurved anterior to the cirrus sac, and a uterus that is not bifurcated at the posterior end (Beveridge & Campbell, 1988; Beveridge & Duffy, 2005). These significant differences in morphology are deemed sufficient to warrant the exclusion of C. acanthocapax from the Rhinoptericolidae at present. Furthermore, adults of C. acanthocapax solely parasitize basking sharks (Beveridge & Campbell, 1988; Beveridge & Duffy, 2005), while adults of rhinoptericolids are known almost exclusively from myliobatiforms. Cetorhinicola now is considered a genus incertae sedis within the superfamily Eutetrarhynchoidea.

Rhinoptericola Carvajal & Campbell, 1975

Synonym: Shirleyrhynchus Beveridge & Campbell, 1988.

Type species: Rhinoptericola megacantha Carvajal & Campbell, 1975.

Other species: Rhinoptericola aetobatidis (Shipley & Hornell, 1906) n. comb.; Rhinoptericola butlerae (Beveridge & Campbell, 1988) n. comb.; Rhinoptericola hexacantha n. sp.; Rhinoptericola jensenae (Schaeffner & Beveridge, 2012b) n. comb.; Rhinoptericola mozambiquensis n. sp.; Rhinoptericola panamensis (Schaeffner, 2016) n. comb.; Rhinoptericola schaeffneri n. sp.

Diagnosis (modified from Palm, 2004)

Scolex acraspedote, elongate, slender. Bothria four in number, elliptoid to deeply ovoid, with free lateral and posterior margins, arranged in dorsal and ventral pairs, not overlapping pars bulbosa; bothrial pits absent. Pintner’s cells absent. Rhyncheal apparatus present. Tentacle sheaths sinuous. Prebulbar organs present. Bulbs long; gland cells in bulbs absent; retractor muscles originate at base of bulbs. Pars postbulbosa short or absent. Tentacles long, with slight basal swelling. Characteristic basal armature present; hooks heteromorphous, solid or hollow, arranged in indistinct rows; macrohooks present or absent; billhooks present or absent. Metabasal armature heteroacanthous typical; hooks heteromorphous, solid or hollow, arranged in alternating ascending half-spiral rows of 6–9 hooks each; hook files 1 and 1′ separated.

Worms apolytic or euapolytic. Proglottids acraspedote. Testes numerous, medullary, arranged in two columns in single layer essentially anterior to ovary. Vas deferens extending from near anterior margin of ovary to anterior margin of cirrus sac, entering cirrus sac at its antero-medial margin; external and internal seminal vesicles absent. Cirrus sac ovoid to elliptoid in shape, bent anteriorly or not, containing coiled cirrus; cirrus unarmed. Genital atrium absent. Genital pores separate, unilateral, at or anterior to mid-level of proglottid; male and female genital pores at same level. Vagina medial in proglottid; vaginal sphincter absent; seminal receptacle present. Ovary terminal in proglottid, H-shaped in dorsoventral view, tetralobed in cross-section, with lobulated margins. Vitellarium follicular; follicles circumcortical, extending entire length of proglottid, interrupted dorsally and ventrally by ovary, partially interrupted ventrally by terminal genitalia. Uterus saccate, medial, dorsal to vagina, bifurcated at posterior end, extending from anterior margin of ovary to anterior margin of proglottid. Uterine pore present or absent. Excretory vessels four, arranged in one dorsal and one ventral pair on each lateral margin of proglottid. Eggs single, essentially spherical, non-embryonated; polar filaments absent. Parasites of rays (Myliobatiformes) and Hemiscylliidae (Orectolobiformes) as adults. Cosmopolitan.

Remarks: Prior to this study, Campbell & Beveridge (1994) and Palm (2004) amended the original diagnosis of Rhinoptericola based on the features of the type and only species, R. megacantha. Palm (2004) reinterpreted the metabasal armature as heteroacanthous typical (rather than atypical) and determined the presence (rather than absence) of prebulbar organs. These features were confirmed in the present study for all members of Rhinoptericola. Palm (2004) also interpreted R. megacantha to possess five hooks per principal row; however, with the addition of data on new species, species transferred to the genus, and reinterpretation of the hooks of R. megacantha, species of Rhinoptericola are now collectively considered to possess six or more hooks per principal row. Additional changes include that, with the exception of one euapolytic species, species of Rhinoptericola are now considered to be apolytic sensu Caira, Jensen & Healy (1999), and that the cirrus was found to be unarmed, rather than armed with spinitriches.

The synonymy of Shirleyrhynchus with Rhinoptericola is supported by both morphological and molecular data (see results of the phylogenetic analysis). Beveridge & Campbell (1988) noted strong morphological similarity between the proglottid anatomy of Shirleyrhynchus and Rhinoptericola, and distinguished the genera solely based on metabasal armature type: heteroacanthous typical armatures in species of Shirleyrhynchus and heteroacanthous atypical armatures in species of Rhinoptericola. Now that species of Rhinoptericola are interpreted to be typical heteroacanths as well, there is no compelling morphological evidence to justify maintaining Shirleyrhynchus as a separate genus.

Nataliella Palm, 2010

Synonyms: None.

Type and only species: Nataliella marcelli Palm, 2010.

Type specimens: Holotype and two paratypes (MPM 15751 [formerly MPM 23200]) and one paratype (MPM 15752 [formerly MPM 23201]).

Voucher specimens: ZMB 7439 (hologenophore; missing).

Remarks: Palm (2010) assigned the genus Nataliella, and its type and only species, Nataliella marcelli, to the family Rhinoptericolidae based on the results of a molecular phylogenetic analysis (Palm et al., 2009) and a scolex morphology unique among tapeworms and shared between N. marcelli and R. megacantha (i.e., elongate scoleces with four bothria and prebulbar organs, but without gland cells in the bulbs). The presence (or absence) of these features was confirmed following examination of detailed photomicrographs of the holotype of N. marcelli (MPM 15751 [formerly MPM 23200]). Unlike species of Rhinoptericola, however, N. marcelli was described as possessing a homeoacanthous metabasal armature (i.e., a metabasal armature with hooks arranged in quincunxes). This differs markedly from paired rows of hooks known for species of Rhinoptericola, but observations of photomicrographs of the holotype were insufficient to conclusively assess armature type for N. marcelli.

Unfortunately, proglottid anatomy is not known for N. marcelli as it was described solely from larval specimens collected from teleosts (families Acanthuridae, Scombridae, Lutjanidae, and Priacanthidae; see Palm, 2010). Despite this lack of information on proglottid anatomy, Nataliella is here retained in the Rhinoptericolidae based on shared scolex features. No information is known about definitive host associations for N. marcelli but given that the species was described from relatively large bony fishes (between 20 and 79 cm standard length; Froese & Pauly, 2019), the definitive host is likely a shark.

Rhinoptericola megacantha Carvajal & Campbell, 1975

Figures 2–6

Synonyms: None.

Redescription (based on holotype and 26 voucher specimens: five gravid worms, 11 mature worms, one immature worm, cross-sections of one scolex and one partial strobila, lactophenol and glycerin egg preparations from one gravid proglottid, and four scoleces, one detached proglottid, and one partial strobila prepared for SEM):

Worms apolytic (Fig. 2A); mature worms 10.7–38.6 mm (24.2 ± 8.4; 12) [38.6 mm] long, gravid worms 23.7–31.6 mm (n = 4) long, maximum width at level of pars bothrialis, pars bulbosa or terminal proglottid; proglottids 39–74 (56 ± 17.0; 5) [56] in total number in mature and 22–74 (51 ± 15.5; 17) in total number in gravid worms.

Scolex (Figs. 2B, 4A and 4B) acraspedote, elongate, slender, 2,616–5,078 (3,973 ± 659.1; 18) [4,019] long, length:width ratio 2.8–6.4 (4.7 ± 1.3; 13):1 [5.2:1]. Pars bothrialis 369–902 (571 ± 127.3; 15) [581] long by 529–963 (751 ± 119.0; 15) [529] wide, with four bothria (Figs. 2B, 4A, 4B, 5A); bothria elliptoid to deeply ovoid, 320–625 (469 ± 79.2; 17; 40) [427–514] long by 188–332 (248 ± 42.3; 13; 28) wide, with free lateral and posterior margins, arranged in dorsal and ventral pairs, not overlapping pars bulbosa; bothrial pits absent. Pintner’s cells absent. Pars vaginalis 1,173–2,609 (1,831 ± 417.8; 18) [1,730] long by 378–793 (586 ± 129.2; 18) [591] wide at midpoint; tentacle sheaths sinuous. Pars bulbosa 1,458–2,410 (2,083 ± 324.9; 18) [2,185] long by 492–741 (593 ± 81.5; 18) [516] wide at midpoint; bulbs very narrowly oblong, thick-walled, muscular, 1,367–2,483 (2,078 ± 321.6; 18; 53) [2,156–2,176] long by 172–306 (231 ±.34.2; 18; 45) [172–195] wide; bulb length:width ratio 4.8–12.7 (9.1 ± 1.6; 18; 45):1 [11.1–12.7:1]; prebulbar organs present; gland cells inside bulbs absent; retractor muscles in bulbs 24–55 (38 ± 7.0; 18; 52) [29–39] wide, originating at base of bulbs. Pars postbulbosa short, 41–128 (79 ± 27.3; 18) [122] long. Scolex length ratio (pars bothrialis length:pars vaginalis length:pars bulbosa length) 1:2.2–6.2 (3.3 ± 1.1; 15):2.4–5.0 (3.7 ± 0.8; 15) [1:3.0:3.8].

Tentacles long, with slight basal swelling, rarely retracted into bulbs, at least 2,206 long, 56–109 (84 ± 13.1; 15; 30) [56–72] wide at base, 81–118 (98 ± 9.9; 14; 22) [82–94] wide at basal swelling, 68–106 (89 ± 11.2; 14; 27) [76–84] wide in metabasal region.

Characteristic basal armature present (Figs. 3E–3H, 4O and 4P), 237–368 (306 ± 29.4; 13; 23) [237–293] long from base of tentacle to start of metabasal armature, consisting of 60–76 (64 ± 2.8; 9) [66] hooks arranged in 8–11 [11] indistinct rows; hooks in posterior-most rows 1–3 uncinate, solid, with or without slight anterior base extensions; hooks in rows 3–6 falcate to bent spiniform or hastate, solid or hollow; hooks in rows 5–7 triangular and dorsoventrally flattened or falcate with or without recurved tips, solid or hollow; four macrohooks in rows 8–9; macrohook on internal surface, amorphous, blunt, solid; macrohooks on external surface uncinate, dorsoventrally flattened, rebated, with recurved tips, solid or hollow; macrohook on antibothrial surface, plow-shaped, hollow, with region devoid of hooks immediately posterior; macrohooks 30–73 (47 ± 9.7; 14; 36) long, 20–57 (35 ± 8.0; 14; 36) high, base 15–29 (20 ± 4.0; 14; 36) long; hooks in anterior-most rows 10–11 spiniform to falcate or rosethorn-shaped, small, thin, solid or hollow; billhooks absent.

Metabasal armature (Figs. 3A–3D, 4M and 4N) heteroacanthous typical; hooks heteromorphous, solid, arranged in alternating ascending half-spiral rows of seven hooks each; rows originating with hooks 1(1′) on internal surface, terminating with hooks 7(7′) in near single file on external surface; hooks 1(1′)–3(3′) not angled towards gap between hooks 1(1′). Hook files 1 and 1′ slightly separated, 14–27 (21 ± 5.5; 5; 6) apart. Hooks 1(1′) uncinate with prominent anterior base extensions, 45–119 (81 ± 16.2; 15; 38) long, 20–68 (39 ± 11.7; 15; 38) high, base 45–103 (67 ± 15.2; 15; 38) long. Hooks 2(2′) falcate, with slightly recurved tips and slight anterior base extensions, 42–100 (71 ± 11.1; 14; 30) long, 27–72 (45 ± 11.3; 14; 30) high, base 26–83 (41 ± 10.4; 14; 30) long. Hooks 3(3′) falcate, with slightly recurved tips and slight anterior base extensions, 47–100 (73 ± 11.3; 11; 26) long, 28–69 (47 ± 10.5; 11; 26) high, base 21–42 (27 ± 5.4; 11; 26) long. Hooks 4(4′) falcate, with slightly recurved tips and slight anterior base extensions, 53–80 (66 ± 8.6; 10; 19) long, 21–57 (43 ± 9.9; 10; 19) high, base 15–29 (22 ± 3.0; 10; 19) long. Hooks 5(5′) falcate with slight anterior base extensions, 33–67 (48 ± 7.9; 11; 24) long, 15–37 (26 ± 5.1; 11; 24) high, base 13–22 (18 ± 2.5; 11; 24) long. Hooks 6(6′) falcate to uncinate with tips extending beyond hook base, with slight anterior base extensions, 25–48 (36 ± 6.0; 12; 24) long, 12–38 (21 ± 5.6; 12; 24) high, base 10–22 (17 ± 3.3; 12; 24) long. Hooks 7(7′) falcate to uncinate with tips extending beyond hook base, with slight anterior base extensions, 22–45 (35 ± 5.4; 12; 22) long, 14–31 (20 ± 4.3; 12; 22) high, base 12–25 (19 ± 3.6; 12; 22) long.

Distal bothrial surfaces (Fig. 4D) with long narrow gladiate spinitriches and capilliform filitriches. Proximal bothrial surfaces near bothrial rims (Fig. 4E) with long narrow gladiate spinitriches and capilliform filitriches, away from bothrial rims (Fig. 4F) with short narrow gladiate spinitriches and acicular filitriches. Scolex proper at apex (Fig. 4H) and between bothria (Fig. 4G) with gladiate spinitriches and acicular to capilliform filitriches. Pars vaginalis (Fig. 4I), pars bulbosa (Fig. 4J), and strobila (Fig. 4K) with capilliform filitriches.

Proglottids acraspedote. Neck 57–257 (124 ± 51.3; 16) long. Immature proglottids 17–64 (41 ± 12.8; 17) [44] in number, wider than long, becoming longer than wide with maturity. Mature proglottids 3–21 (9 ± 4.0; 17) [12] in number; terminal mature proglottids in mature worms 1,629–3,170 (2,232 ± 455.0; 12) [3,170] long by 402–945 (598 ± 173.6; 12) [680] wide. Gravid proglottids 1–4 (n = 4) in number; terminal gravid proglottids 2,295–3,260 (n = 4) long by 624–1,209 (n = 4) wide.

Testes 41–67 (57 ± 6.6; 16) [58] in total number, 20–26 (23 ± 1.9; 15) [23] pre-poral, 21–43 (34 ± 5.7; 15) [35] post-poral, 39–137 (77 ± 20.9; 16; 48) [80–137] long by 85–218 (133 ± 34.2; 15; 45) [161–193] wide, in field from anterior margin of proglottid to ovary, slightly overlapping anterior margin of ovary, arranged in two columns (Figs. 2C, 5C and 5D), essentially in single layer (Figs. 5C and 5D). Vas deferens extending from near anterior margin of ovary to anterior margin of cirrus sac, entering cirrus sac at its antero-medial margin, coiled primarily anterior to cirrus sac; external and internal seminal vesicles absent. Cirrus sac ovoid to elliptoid, occasionally bent anteriorly, 241–672 (449 ± 121.7; 14) [672] long by 149–350 (225 ± 51.6; 15) [269] wide, containing coiled cirrus; cirrus unarmed, thin-walled. Genital atrium absent. Genital pores separate (Fig. 4L), at same level, unilateral, 60–79% (71% ± 4.5%; 17) [75%] of proglottid length from posterior margin of proglottid in mature proglottids and 65–74% (n = 4) in gravid proglottids. Vagina thick-walled, weakly sinuous, extending from ootype along midline of proglottid to anterior margin of cirrus sac, then laterally at level of cirrus sac, terminating in female genital pore, greatly expanded when sperm-filled; vaginal sphincter absent; seminal receptacle present. Ovary terminal in proglottid, H-shaped in dorsoventral view, tetralobed in cross-section, 283–662 (476 ± 109.2; 16) [584] long by 243–599 (437 ± 109.5; 14) [508] wide, with lobulated margins; ovarian isthmus near center of ovary. Mehlis’ gland near posterior margin of ovary. Vitellarium follicular; follicles circumcortical, 15–79 (27 ± 13.1; 16; 47) [30–37] long by 12–77 (32 ± 13.0; 15; 44) [28–57] wide, extending entire length of proglottid, interrupted dorsally and ventrally by ovary, partially interrupted ventrally by terminal genitalia; post-ovarian vitelline follicles absent. Uterus saccate, medial, dorsal to vagina (Figs. 2C, 5D), bifurcated at posterior end (Figs. 2C, 5D), extending from anterior margin of ovary to anterior margin of proglottid. Uterine duct entering uterus at mid-level. Uterine pore absent. Excretory vessels four, arranged in one dorsal and one ventral pair on each lateral margin of proglottid. Eggs (Fig. 6) single, essentially spherical, 15–23 (17 ± 2.2; 4; 12) in diameter in situ, 26–29 (27 ± 1.0; 1; 10) in diameter ex situ, non-embryonated; polar filaments absent.

Type host: Rhinoptera bonasus (Mitchill, 1815) (Rhinopteridae: Myliobatiformes).

Additional hosts: Rhinoptera brasiliensis Müller, 1836 and Rhinoptera marginata (Geoffroy St. Hilaire, 1817) (Rhinopteridae: Myliobatiformes); Hypanus say (Lesueur, 1817) (Dasyatidae: Myliobatiformes).

Type locality: Atlantic Ocean, Virginia, USA: Chesapeake Bay.

Additional localities: Atlantic Ocean, Brazil: Southern and southeastern Brazil. Atlantic Ocean, Senegal: St. Louis (16°1′28″N, 16°30′33″W). Atlantic Ocean, South Carolina, USA: Awendaw (33°02′07.78″N, 79°32′47.24″W; 33°0′34.27″N, 79°29′8.82″W), Bull’s Bay; and Charleston (32°45′2.53″N, 79°53′48.28″W; 32°44′51.30″N, 79°53′44.07″W; 32°47′18.08″N, 79°53′18.77″W), Charleston Harbor. Caribbean Sea, Belize: Gales Point Manatee (17°13′1.0″N, 88°19′01.4″W), Inner Channel. Caribbean Sea, Venezuela: Caimare Chico, Zulia, Gulf of Venezuela. Gulf of Mexico, Louisiana, USA: Chandeleur Islands (29°57′9.54″N, 88°50′38.98″W). Gulf of Mexico, Mississippi, USA: East Ship Island (30°14′37.70″N, 88°46′37.62″W); Horn Island (30°14′1.44″N, 88°40′5.47″W; 30°14′24.54″N, 88°52′25.25″W; 30°15′04″N, 88°42′42″W); off the Gulf Coast Research Lab, Ocean Springs (30°23′33.55″N, 88°47′51.79″W); and Ship Island (30°13′13.53″N, 88°54′52.48″W).

Site of infection: Spiral intestine.

Type specimens: Holotype (USNM 1369398 [originally USNPC 73835]) and one paratype (USNM 1369399 [originally USNPC 73836]).

Voucher specimens: HWML 21032 (Mayes & Brooks, 1981), HWML 34972; BMNH 2008.5.21 (hologenophore; Olson et al., 2010); LRP 10454–10546 (this study), LRP 10432–10453 (hologenophores; this study); USNM 1661576–1661587 (this study).

Museum specimens examined: Holotype (USNM 1369398) and two voucher specimens (HWML 21032 and HWML 34972).

Remarks: As the type species of the genus, this species has received relatively little attention since its detailed description by Carvajal & Campbell (1975). In his treatment of the species based on examination of the holotype and paratype, Palm (2004) presented a revised version of the description of Carvajal & Campbell (1975) using updated terminology. The two most significant changes Palm (2004) made were the reinterpretation of the metabasal armature from heteroacanthous atypical to heteroacanthous typical, and the observation of the presence, rather than absence, of prebulbar organs. The redescription herein is based on the holotype (which was remeasured), and new voucher material. It includes the first detailed scanning electron micrographs of the hooks and microthrix pattern for the species (Fig. 4). The species is redrawn from specimens from the type host, Rhinoptera bonasus, and from Rhinoptera brasiliensis (Figs. 2, 3). Photomicrographs of cross-sections (Fig. 5) and an egg (Fig. 6) are provided, and the known definitive host associations and geographic range for the species are expanded.

Most significant in this redescription is the reinterpretation of the metabasal armature. Carvajal & Campbell (1975) and Palm (2004) both interpreted the metabasal armature to comprise five hooks per principal row with an additional row of three small hooks on the external surface (see fig. 4 of Carvajal & Campbell, 1975). The metabasal armature is reinterpreted here to simply consist of seven hooks per principal row (see Figs. 3C, 4N); the rows of three small hooks on the external surface observed by Carvajal & Campbell (1975) and Palm (2004) are now considered part of the principal rows. Additional changes include recognizing R. megacantha to be apolytic rather than euapolytic sensu Caira, Jensen & Healy (1999) (see Fig. 2A), to possess a cirrus that is unarmed rather than armed (see Fig. 4C), and to possess genital pores that are unilateral rather than irregularly alternating (see Fig. 2A).

Not unexpectedly, given the greater number of measured specimens on which this redescription is based compared to the original description of Carvajal & Campbell (1975) (i.e., 18 vs six, respectively), ranges for most measurements were expanded, or differ slightly, from those in the original description (see Table S2). There are, however, two instances where ranges differ largely: Carvajal & Campbell (1975) reported a total length of 35–65 mm while the specimens examined in this study (including the holotype) measured 10.7–38.6 mm in total length for mature worms and 23.7–31.6 mm for gravid worms; similarly, Carvajal & Campbell (1975) reported terminal proglottids of R. megacantha to be 2,200–4,000 µm long (without specifying maturity) while we report total lengths of 1,629–3,170 µm and 2,295–3,260 µm for mature and gravid terminal proglottids, respectively. Interestingly, the holotype—a mature, non-gravid worm—was one of the longest specimens measured in this study, and possessed the longest terminal proglottid. This suggests that the additional five specimens measured by Carvajal & Campbell (1975) that were not included here may also be particularly large worms.

Prior to this study, R. megacantha had been reported from the American cownose ray, Rhinoptera bonasus, from both the Chesapeake Bay, USA (Carvajal & Campbell, 1975) and the Gulf of Venezuela, Venezuela (Mayes & Brooks, 1981), as well as from the Ticon cownose ray, Rhinoptera brasiliensis, from the Gulf of Mexico, USA (as Rhinoptera bonasus; Call, 2007) and from the Atlantic coast of Brazil (Napoleão et al., 2015). Based on updated geographic distributions for species of Rhinoptera van Hasselt, 1824 (see Last et al., 2016), the identity for the host of R. megacantha from the Gulf of Venezuela is uncertain and could have been either Rhinoptera bonasus or Rhinoptera brasiliensis. Additional voucher material used for this redescription further expands the hosts and geographic localities from which R. megacantha is known to include an additional species of cownose ray, the Lusitanian cownose ray, Rhinoptera marginata, from Senegal, as well as the bluntnose stingray, Hypanus say, from off South Carolina, USA. Thus, R. megacantha is now understood to parasitize three species of cownose rays (Rhinopteridae) and one species of stingray (Dasyatidae) from both sides of the Atlantic Ocean, including the Chesapeake Bay, South Carolina, the Gulf of Mexico, Belize, Venezuela, Brazil, and Senegal.

Rhinoptericola butlerae (Beveridge & Campbell, 1988) n. comb.

Figure 7

Synonym: Shirleyrhynchus butlerae Beveridge & Campbell, 1988.

Redescription (based on holotype, six paratypes, and 10 voucher specimens: one gravid worm, one mature worm, three immature worms, and four complete scoleces and one partial scolex prepared for SEM):

Worms apolytic; mature worms 15.5–18.9 mm (n = 3) [15.5 mm] long, gravid worms 22.7 mm (n = 1) long, maximum width at level of pars bothrialis or pars bulbosa; proglottids 42–51 (n = 3) [42] in total number in mature and 50 (n = 1) in total number in gravid worms.

Scolex (Figs. 7A and 7B) acraspedote, elongate, slender, 4,533–5,899 (5,081 ± 441.1; 11) [4,533] long, length:width ratio 5.0–8.9 (6.4 ± 1.2; 9):1 [5.7:1]. Pars bothrialis 418–714 (599 ± 90.2; 11) [622] long by 664–952 (794 ± 100.3; 9) [790] wide, with four bothria (Figs. 7A and 7B); bothria elliptoid to very deeply ovoid, 373–653 (493 ± 70.2; 11; 28) [492–519] long by 169–273 (223 ± 33.2; 11; 21) [218] wide, with free lateral and posterior margins, arranged in dorsal and ventral pairs, not overlapping pars bulbosa; bothrial pits absent. Pintner’s cells absent. Pars vaginalis 2,478–3,420 (2,854 ± 306.0; 11) [2,591] long by 348–785 (562 ± 117.6; 11) [447] wide at midpoint; tentacle sheaths sinuous. Pars bulbosa 1,752–2,476 (2,101 ± 238.0; 11) [1,752] long by 558–1,059 (662 ± 139.2; 11) [558] wide at midpoint; bulbs very narrowly oblong, thick-walled, muscular, 1,641–2,450 (2,047 ± 244.5; 11; 30) [1,641–1,745] long by 186–307 (233 ± 28.7; 11; 29) [203–220] wide; bulb length:width ratio 5.8–11.3 (8.9 ± 1.5; 11; 27):1 [7.9–8.1:1]; prebulbar organs present; gland cells inside bulbs absent; retractor muscles in bulbs 20–56 (38 ± 10.3; 10; 28) [31–53] wide, originating at base of bulbs. Pars postbulbosa short, 76–273 (151 ± 64.7; 11) [136] long. Scolex length ratio (pars bothrialis length:pars vaginalis length:pars bulbosa length) 1:3.7–6.1 (4.8 ± 0.7; 11):2.8–5.1 (3.6 ± 0.7; 11) [1:4.2:2.8].

Tentacles long, with slight basal swelling, rarely retracted into bulbs, at least 2,219 long, 82–159 (101 ± 19.1; 10; 24) [105] wide at base, 83–143 (107 ± 16.2; 9; 22) wide at basal swelling, 77–136 (102 ± 20.2; 9; 23) wide in metabasal region.

Characteristic basal armature present (Figs. 7M and 7N), 354–492 (431 ± 38.8; 9; 18) [492] long from base of tentacle to start of metabasal armature, consisting of 83–99 (91 ± 6.4; 5) [83] hooks arranged in 8–12 [12] indistinct rows; hooks in posterior-most rows 1–3 uncinate, solid, with or without slight anterior base extensions; hooks in rows 3–7 falcate to spiniform or hastate, large, thin, and erect when falcate, solid or hollow; hooks in rows 7–9 triangular and dorsoventrally flattened or falcate with or without recurved tips, solid or hollow; 3–4 macrohooks in rows 9–10; one macrohook on internal surface uncinate, dorsoventrally flattened, rebated to amorphous and blunt, occasionally small enough as to be unrecognizable as macrohook; two macrohooks on external surface, uncinate, dorsoventrally flattened, rebated, with recurved tips, solid or hollow; one anterior-most macrohook on antibothrial surface, plow-shaped to uncinate, dorsoventrally flattened, rebated, hollow, with region devoid of hooks immediately posterior; macrohooks 32–63 (46 ± 8.9; 5; 13) long, 26–56 (39 ± 8.6; 5; 13) high, base 11–28 (18 ± 4.8; 5; 13) long; hooks in anterior-most rows 11–12 spiniform to falcate or rosethorn-shaped, small, thin, solid or hollow; billhooks absent.

Metabasal armature (Figs. 7K and 7L) heteroacanthous typical; hooks heteromorphous, solid, arranged in alternating ascending half-spiral rows of seven hooks each; rows originating with hooks 1(1′) on internal surface, terminating with hooks 7(7′) in near single file on external surface; hooks 1(1′)–3(3′) not angled towards gap between hooks 1(1′). Hook files 1 and (1′) slightly separated, 24–42 (n = 2; 4) apart. Hooks 1(1′) uncinate with prominent anterior base extensions, 65–126 (86 ± 18.2; 9; 25) long, 38–82 (54 ± 11.9; 9; 25) high, base 53–102 (72 ± 13.1; 9; 25) long. Hooks 2(2′) falcate, with slightly recurved tips and slight anterior base extensions, 66–125 (97 ± 23.5; 5; 12) long, 42–99 (70 ± 20.8; 5; 12) high, base 31–66 (47 ± 11.1; 5; 12) long. Hooks 3(3′) falcate, with slightly recurved tips and slight anterior base extensions, 62–119 (92 ± 22.9; 5; 9) long, 44–108 (68 ± 23.1; 5; 9) high, base 27–42 (34 ± 5.6; 5; 9) long. Hooks 4(4′) falcate, with slightly recurved tips and slight anterior base extensions, 55–99 (71 ± 16.7; 4; 9) long, 29–70 (46 ± 13.5; 4; 9) high, base 19–39 (26 ± 6.7; 4; 9) long. Hooks 5(5′) falcate with slight anterior base extensions, 36–75 (56 ± 13.5; 5; 13) long, 20–59 (37 ± 11.2; 5; 13) high, base 14–26 (20 ± 4.6; 5; 13) long. Hooks 6(6′) falcate to uncinate with tips extending beyond hook base, with slight anterior base extensions, 24–69 (39 ± 12.9; 9; 25) long, 12–38 (23 ± 6.2; 9; 25) high, base 10–31 (20 ± 4.9; 9; 25) long. Hooks 7(7′) falcate to uncinate with tips extending beyond hook base, with slight anterior base extensions, 20–64 (39 ± 12.7; 9; 26) long, 15–37 (24 ± 5.7; 9; 26) high, base 18–31 (26 ± 3.6; 9; 26) long.

Distal bothrial surfaces (Fig. 7C) with long narrow gladiate spinitriches and capilliform filitriches. Proximal bothrial surfaces near bothrial rims (Fig. 7D) with short narrow gladiate spinitriches and capilliform filitriches, away from bothrial rims (Fig. 7E) with acicular filitriches. Scolex proper at apex (Fig. 7G) with gladiate spinitriches and acicular filitriches, and between bothria (Fig. 7F) with acicular to capilliform filitriches. Pars vaginalis (Fig. 7H), pars bulbosa (Fig. 7I), and strobila (Fig. 7J) with capilliform filitriches.

Proglottids acraspedote. Neck 155–164 (n = 2) long. Immature proglottids 35–46 (n = 3) [35] in number, wider than long, becoming longer than wide with maturity. Mature proglottids 5–7 (n = 2) [7] in number; terminal mature proglottids in mature worms 1,085–1,529 (n = 2) [1,085] long by 293–500 (n = 2) [500] wide. Gravid proglottids two (n = 1) in number; terminal gravid proglottids 1,480 by 683 (n = 1) wide; detached gravid proglottids 1,735–2,213 (n = 3) long by 747–766 (n = 3) wide.

Testes 50–60 (54 ± 4.4; 3; 5) [57] in total number, 19–28 (n = 4) [21–28] pre-poral, 29–32 (n = 4) [32] post-poral, 51–60 (55 ± 4.2; 2; 6) [51–60] long by 90–157 (114 ± 23.0; 2; 6) [118–157] wide, in field from anterior margin of proglottid to ovary, slightly overlapping anterior margin of ovary, arranged in two columns, essentially in single layer. Vas deferens extending from near anterior margin of ovary to anterior margin of cirrus sac, entering cirrus sac at its antero-medial margin, coiled primarily anterior to cirrus sac; external and internal seminal vesicles absent. Cirrus sac elliptoid, bent anteriorly, 241 (n = 1) long by 195 (n = 1) wide, containing coiled cirrus; cirrus unarmed, thin-walled. Genital atrium absent. Genital pores separate, at same level, unilateral, 64–72% (n = 3) [64%] of proglottid length from posterior margin in mature proglottids.

Vagina thick-walled, weakly sinuous, extending from ootype along midline of proglottid to anterior margin of cirrus sac, then laterally at level of cirrus sac, terminating in female genital pore, greatly expanded when sperm-filled; vaginal sphincter absent; seminal receptacle present. Ovary terminal in proglottid, H-shaped in dorsoventral view, tetralobed in cross-section, 509 long by 237–383 (n = 2) [383] wide, with lobulated margins; ovarian isthmus near center of ovary. Mehlis’ gland near posterior margin of ovary. Vitellarium follicular; follicles circumcortical, 11–21 (16 ± 3.3; 3; 9) [14–16] long by 8–31 (20 ± 8.8; 3; 9) [8–13] wide, extending entire length of proglottid, interrupted dorsally and ventrally by ovary, partially interrupted ventrally by terminal genitalia; post-ovarian vitelline follicles absent. Uterus saccate, medial, dorsal to vagina, bifurcated at posterior end, extending from anterior margin of ovary to anterior margin of proglottid. Uterine duct not observed. Uterine pore present. Excretory vessels four, arranged in one dorsal and one ventral pair on each lateral margin of proglottid. Eggs single, essentially spherical, 19–21 (n = 2) in diameter in situ, non-embryonated; polar filaments absent.

Type host: Hemitrygon fluviorum (Ogilby, 1908) (Dasyatidae: Myliobatiformes).

Additional hosts: Hemitrygon bennetti (Müller & Henle, 1841), Himantura tutul Borsa, Durand, Shen, Alyza, Solihin & Berrebi, 2013, Maculabatis gerrardi (Gray, 1851), Pastinachus ater (Macleay, 1883), and Pastinachus solocirostris Last, Manjaji & Yearsley, 2005 (Dasyatidae: Myliobatiformes); Rhinoptera javanica Müller & Henle, 1841 and Rhinoptera neglecta Ogilby, 1912 (Rhinopteridae: Myliobatiformes); Chiloscyllium punctatum Müller & Henle, 1838 (Hemiscyliidae; Orectolobiformes).

Type locality: Coral Sea, Australia: Deception Bay, Queensland.

Additional localities: Arafura Sea, Australia: East of Wessel Islands (11°17′44″S, 136°59′48″E), Northern Territory. Gulf of Carpentaria, Australia: Weipa (12°35′11″S, 141°42′34″E), Queensland. Timor Sea, Australia: Dundee Beach (12°45′33″S, 130°21′7″E), Northern Territory, Fog Bay. Java Sea, Indonesia: Gusungnge near Pagatan market (03°36′46.10″S, 115°55′05.10″E), South Kalimantan; and Pagatan market (03°36′36.00″S, 115°54′59.40″E), South Kalimantan. Makassar Strait, Indonesia: Muara Pasir (01°45′58.92″S, 116°23′36.09″E), East Kalimantan. South China Sea, Malaysia: Mukah (02°53′52.16″N, 112°05′44.12″E), Sarawak. South China Sea, Viet Nam: Cat Ba (20°43′31.1″N, 107°02′54.9″E), Haiphong Province, Gulf of Tonkin; and Long Hai (10°22′60.00″N, 107°13′60.00″E), Ba Ria Province.

Site of infection: Spiral intestine.

Type specimens: Holotype (AHC 44088 [originally SAM V4088]), seven paratypes (AHC 22773 [originally SAM S2773]; whole mounts, serial sections and mounted tentacles), one paratype (BMNH 1987.5.1.1), and one paratype (USNM 1375081 [originally USNPC 79701]).

Voucher specimens: LRP 10559–10569 (Schaeffner & Beveridge, 2014), LRP 10547–10549, LRP 10551, and LRP 10554–10557 (this study), LRP 10550, LRP 10552, LRP 10553, and LRP 10558 (hologenophores, this study); QM G239454–G239456 (this study).

Museum specimens examined: Holotype (AHC 44088), eight paratypes (AHC 22773-2, AHC 22773-3, AHC 22773-6, AHC 22773-7, AHC 22773-8, AHC 22773-12–14 [sections of one specimen], AHC 22773-15 [sections of one specimen], and USNM 1375081), and one voucher specimen (USNM 1394286 [originally USNPC 99285]).

Remarks: Rhinoptericola butlerae bears a strong morphological similarity to R. megacantha, but the two are readily distinguished from one another based on features of the basal armature. Rhinoptericola butlerae has a greater total number of hooks in the basal armature as compared to R. megacantha (i.e., 83–99 vs 60–67, respectively). Anterior to the first one to three rows of uncinate, solid hooks in the basal armature, R. butlerae possesses several rows of large, thin, erect, widely-spaced hastate hooks; in R. megacantha, these hastate hooks are smaller, thicker, less erect, and more densely packed—a difference easily observed in scanning electron micrograph comparisons between the two species (see Fig. 7N for R. butlerae vs Fig. 4P for R. megacantha). While the ranges for the total lengths of their basal armatures (from base of tentacle to start of metabasal armature) overlap slightly, R. butlerae tends to have a longer basal armature as compared to R. megacantha (i.e., 354–492 µm vs 237–368 µm, respectively). The two species also differ slightly in their scolex microthrix patterns: R. butlerae possesses only acicular to capilliform filitriches on the scolex proper between the bothria (see Fig. 7F) while R. megacantha possesses both gladiate spinitriches and acicular to capilliform filitriches in the same region (see Fig. 4G). In addition to these morphological differences, the two species differ in 28S sequence data by 20–24 base pairs (bp) (see Table 4).

Though Beveridge & Campbell (1998) and Palm (2004) each provided updated descriptions for species of Shirleyrhynchus, both works were published at a time when R. butlerae (as Shirleyrhynchus butlerae Beveridge & Campbell, 1988) was considered a junior synonym of Shirleyrhynchus aetobatidis (now Rhinoptericola aetobatidis; see below) and so neither redescription reliably characterizes the morphology of R. butlerae, alone. Schaeffner (2016) considered R. butlerae to be valid (as S. butlerae) and provided updated measurements and interpretations for select features of the scolex based on a reexamination of six paratypes. We confirmed the presence of seven, rather than eight, hooks per principal row in the metabasal armature (see Fig. 7L) and the arrangement of the hooks in the basal armature as being in rows, rather than in quincunxes (see Figs. 7M and 7N), as suggested by Schaeffner (2016). However, unlike Schaeffner (2016), who reinterpreted the orientation of principal rows in the metabasal armature as starting on the antibothrial tentacle surface and terminating on the bothrial tentacle surface, we observed the internal-to-external orientation reported by Beveridge & Campbell (1988) (see Figs. 7K and 7L and Fig. S1). Additionally, we suggest that R. butlerae possesses three or four—rather than four—macrohooks in the basal armature; for several specimens examined from both type and voucher material, what would positionally be considered the fourth macrohook was indistinguishable in size from the surrounding hooks.

The original line drawings by Beveridge & Campbell (1988)—in combination with the reinterpretation of the armature provided by Schaeffner (2016)—are sufficiently detailed to obviate the need for new illustrations. Instead, this redescription provides the first SEM data for the species and an updated interpretation of the proglottid anatomy. The following changes from the original description by Beveridge & Campbell (1988) are made based on examination of new material and the majority of the type material: cirrus sac unarmed rather than armed, genital pores unilateral rather than irregularly alternating, and the absence rather than presence of a genital atrium. Combining data for the remeasured holotype and six paratypes of R. butlerae with measurements from new material changed the ranges for most morphological features only negligibly from those presented in the original description (see Table S2). Notable differences include total number of proglottids in gravid worms (up to 38 vs 50 herein) and ovary length (180–260 µm vs 509 µm herein).

The known host associations for R. butlerae are expanded significantly herein (see Table 3) from having been originally described from Hemitrygon fluviorum and Pastinachus ater (Dasyatidae) to include Hemitrygon bennetti, Himantura tutul, Maculabatis gerrardi, and Pastinachus solocirostris (Dasyatidae), Rhinoptera javanica and Rhinoptera neglecta (Rhinopteridae), and Chiloscyllium punctatum (Hemiscylliidae). The reports from Hima. tutul, M. gerrardi, P. solocirostris, and C. punctatum are, however, originally attributable to Schaeffner & Beveridge (2014). In their paper, Schaeffner & Beveridge (2014) reported R. butlerae from these four host species from Indonesia and Malaysia (i.e., the island of Borneo), but as these reports occurred during a time when the name Shirleyrhynchus butlerae was still considered a junior synonym of Shirleyrhynchus aetobatidis, they were made using the name S. aetobatidis. Examination of voucher specimens associated with these reports (i.e., one each from Hima. tutul, M. gerrardi, P. solocirostris, and C. punctatum), augmented by additional new voucher material from all but C. punctatum, confirmed them to be R. butlerae (see Table 3). The geographic distribution is also expanded herein northward from Australia to Viet Nam.

Rhinoptericola panamensis (Schaeffner, 2016) n. comb.

Synonym: Shirleyrhynchus panamensis Schaeffner, 2016.

Type host: Urotrygon aspidura (Jordan & Gilbert, 1882) (Urotrygonidae: Myliobatiformes).

Additional hosts: Styracura pacifica (Beebe & Tee-Van, 1941) (Potamotrygonidae: Myliobatiformes).

Type locality: Pacific Ocean, Panama: Off Palo Seco (7°34′33.5″N, 81°00′42.8″W), Veraguas, Golfo de Montijo.

Additional localities: Pacific Ocean, Panama: Playa de Caleta off Isla Cebaco (7°29′37.9″N, 81°13′21.8″W), Veraguas, Golfo de Montijo.

Site of infection: Spiral intestine.

Type specimens: Holotype (MIUP-LAV-002), two paratypes (USNM 1298205–1298206), and one paratype (MZUSP 7766).

Museum specimens examined: Holotype (MIUP-LAV-002) and two paratypes (USNM 1298205–1298206).

Remarks: Schaeffner (2016) described Rhinoptericola panamensis based on four whole-mounted specimens and two specimens prepared for SEM, all of which were immature worms. Examination of the holotype and two paratypes was sufficient to confirm that the scolex morphology of R. panamensis aligns with the revised generic diagnosis for Rhinoptericola (i.e., four bothria, pre-bulbar organs, no gland cells in the bulbs, a characteristic basal armature, and a heteroacanthous typical heteromorphous metabasal armature with six or more hooks per principal row). Thus, the species is hereby transferred to the genus Rhinoptericola despite having no knowledge of its proglottid anatomy. The reexamination of type material, however, also allowed for the reinterpretation of, and collection of additional information on, aspects of the metabasal and basal armatures. We observed the principal rows in the metabasal armature to begin on the internal tentacle surface and terminate on the external tentacle surface, as opposed to the bothrial to antibothrial orientation specified in the original description by Schaeffner (2016) (see Fig. S1). Additionally, as it has become clear that total number of hooks in the basal armature can be an important feature for distinguishing between species of Rhinoptericola, it is here noted that the holotype of R. panamensis possesses 60 hooks in the basal armature. This easily distinguishes R. panamensis from R. butlerae, which possesses 83–99 hooks in the basal armature.

Based on quantitative features of the scolex, R. panamensis is morphologically indistinguishable from R. megacantha (see Fig. S2; as R. panamensis was originally described in the genus Shirleyrhynchus, the two species were not compared to one another prior to this study). They are similarly identical in terms of qualitative features of the scolex. Both have characteristic basal armatures with four macrohooks and a similar hook shape, number, and arrangement throughout, and metabasal armatures with seven hooks per principal row that begin on the internal tentacle surface and terminate on the external tentacle surface. In terms of scolex microthrix patterns, Schaeffner (2016) described R. panamensis as possessing distal bothrial surfaces with gladiate spinitriches and proximal bothrial surfaces with acicular to capilliform filitriches (see figs. 4E and 4F of Schaeffner, 2016), whereas R. megacantha is herein redescribed as possessing distal and proximal bothrial surfaces with both gladiate spinitriches and capilliform (or acicular) filitriches (see Figs. 4D and 4E). This is the only morphological difference between the two species and warrants further investigation.

Despite being essentially indistinguishable based on the morphological data at hand, the two species are not synonymized until proglottid anatomy can be assessed for R. panamensis and material preserved in 95% ethanol for R. panamensis is available for DNA sequencing to confirm conspecificity with R. megacantha.

Rhinoptericola aetobatidis (Shipley & Hornell, 1906) n. comb.

Synonyms: Tetrarhynchus aetobatidis Shipley & Hornell, 1906; Tentacularia aetobatidis (Shipley & Hornell, 1906) Southwell, 1929; Shirleyrhynchus aetobatidis (Shipley & Hornell, 1906) Beveridge & Campbell, 1988.

Type host: Aetobatus ocellatus (Kuhl, 1823) (as Aetobatis [sic] narinari [Euphrasen, 1790]) (Aetobatidae: Myliobatiformes).

Additional hosts: Brevitrygon imbricata (Bloch & Schneider, 1801) or Brevitrygon sp. 1 sensu Fernando et al. (2019) (as Trygon walga Müller & Henle, 1841; see Jensen & Guyer, 2021) and Neotrygon indica Pavan-Kumar, Kumar, Pitale, Shen & Borsa, 2018 or Neotrygon caeruleopunctata Last, White & Séret, 2016 (as Trygon kuhlii [sic] Müller & Henle, 1841) (Dasyatidae: Myliobatiformes).

Type locality: Laccadive Sea, Sri Lanka: Dutch Bay Spit, Gulf Mannar.

Site of infection: Spiral intestine.

Type specimens: Holotype (VNHM 2099 [originally NMV 2099]; missing).

Remarks: Rhinoptericola aetobatidis has a complex taxonomic history that was well summarized by Schaeffner (2016). He also provided updated illustrations, scolex measurements, and morphological interpretations based on reexamination of the holotype. For this study, the holotype (VNHM 2099) of the species was requested from the Natural History Museum in Vienna for examination, but unfortunately was reported missing (P. Frade, 2020, pers. comm.). The decision here to transfer R. aetobatidis to Rhinoptericola was thus based on the report of its scolex morphology as given by Schaeffner (2016) (i.e., four bothria, the presence of prebulbar organs but lack of gland cells in the bulbs, a characteristic basal armature, and a heteroacanthous typical heteromorphous metabasal armature). These features are consistent with, and unique to, members of the genus Rhinoptericola. Because the holotype of R. aetobatidis was an immature specimen, the proglottid anatomy of R. aetobatidis remains unknown.

Based on the illustrations and interpretations of the armature of the holotype of R. aetobatidis by Schaeffner (2016), the species is distinguished easily from R. megacantha, R. butlerae, and R. panamensis by its possession of two (vs more than two) macrohooks in the basal armature, and an orientation of metabasal hook rows from external to internal (vs from internal to external) tentacle surfaces. Eight specimens of the type host (Aetobatus ocellatus) collected in 2018 from the type locality (off Sri Lanka) were examined as part of this study, but unfortunately, no specimens of R. aetobatidis were found in those host specimens, nor in specimens of A. ocellatus examined from Australia, Indonesia, and the Solomon Islands.

Consideration of older and more recent host reports for R. aetobatidis, beyond those from its type host, revealed both to be in need of revision. Shipley & Hornell (1906) reported Trygon walga and Southwell (1924) reported T. kuhlii as hosts of R. aetiobatidis, both from Sri Lanka. In light of information presented by Fernando et al. (2019) and Last et al. (2016) (see also Jensen & Guyer, 2021) on the elasmobranchs of Sri Lanka, the identities of these host species are doubtful. Based on their distributions, Brevitrygon imbricata or Brevitrygon sp. 1 sensu Fernando et al. (2019) are the most likely candidates for the host species reported as T. walga, and Neotrygon indica or N. caeruleopunctata could either be the host species reported as T. kuhlii. Given the potential for R. aetobatidis to parasitize species in multiple genera of batoids in Sri Lanka, we examined three specimens of N. indica and one specimen each of Narcine cf. lingula sensu Fernando et al. (2019), Pastinachus ater, and Himantura tutul collected from Sri Lanka in 2018 in search of specimens of R. aetobatidis, but none were found. Thus, the host records of R. aetobatidis fom Sri Lanka remain uncertain. More recently, Schaeffner & Beveridge (2014) reported Shirleyrhynchus aetobatidis from the dasyatids Himantura tutul, Maculabatis gerrardi, and Pastinachus ater (as Himantura uarnak [Gmelin, 1789], Himantura gerrardi [Gray, 1851], and Pastinachus atrus [MacLeay, 1883], respectively), and from P. solocirostris and the hemiscylliid Chiloscyllium punctatum, during a time when S. aetobatidis was the valid name with S. butlerae its junior synonym (see Remarks section for R. butlerae). Voucher specimens of Schaeffner & Beveridge (2014) from each of these host species were examined and have been found to be consistent with R. butlerae (see Table 3). Finally, as mentioned in the Introduction, the specimen of R. aetobatidis (as Shirleyrhynchus aetobatidis; LRP 4275) from Himantura australis (as Himantura cf. uarnak) included by Palm et al. (2009) and Olson et al. (2010) in their phylogenetic analysis was subsequently determined to be misidentified and is actually a specimen of the eutetrarhynchid Parachristianella indonesiensis (see Schaeffner, 2016).

Rhinoptericola jensenae (Schaeffner & Beveridge, 2012b) n. comb.

Figures 8–10

Synonym: Prochristianella jensenae Schaeffner & Beveridge, 2012b, in part.

Redescription (based on four paratypes and 17 voucher specimens: three gravid worms, five mature worms, four immature worms, one incomplete worm, cross-sections of one terminal proglottid, and three scoleces prepared for SEM):

Worms apolytic (Fig. 8A); mature worms 3.4–6.3 mm (4.6 ± 1.2; 7) long, gravid worms 4.3–5.1 mm (n = 3) long, maximum width at level of pars bothrialis, pars bulbosa, or gravid proglottid; proglottids 6–11 (9 ± 1.6; 7) in total number in mature and 10–12 (n = 3) in total number in gravid worms.

Scolex (Figs. 8B, 10A and 10B) acraspedote, elongate, slender, 1,133–1,962 (1,603 ± 224.0; 17) long, length:width ratio 3.3–7.8 (5.3 ± 1.3; 15):1. Pars bothrialis 185–329 (274 ± 39.2; 17) long by 214–357 (286 ± 36.8; 17) wide, with four bothria (Figs. 8B, 10B); bothria elliptoid to narrowly elliptoid, 179–282 (231 ± 28.2; 17; 48) long by 68–135 (99 ± 24.3; 6; 18) wide, with free lateral and posterior margins, arranged in dorsal and ventral pairs, not overlapping pars bulbosa; bothrial pits absent. Pintner’s cells absent. Pars vaginalis 701–1,336 (1,085 ± 185.4; 16) long by 109–191 (155 ± 23.8; 17) wide at midpoint; tentacle sheaths sinuous. Pars bulbosa 383–626 (524 ± 75.4; 16) long by 152–252 (208 ± 26.0; 16) wide at midpoint; bulbs very narrowly oblong, thick-walled, muscular, 342–624 (495 ± 81.9; 17; 47) long by 53–92 (72 ± 9.4; 17; 50) wide; bulb length:width ratio 1:4.7–11.3 (7.0 ± 1.5; 17; 46):1; prebulbar organs present; gland cells inside bulbs absent; retractor muscles in bulbs 9–24 (14 ± 3.5; 17; 51) wide, originating at base of bulbs. Pars postbulbosa short or absent, 6–42 (19 ± 11.5; 13) long when present. Scolex length ratio (pars bothrialis length:pars vaginalis length:pars bulbosa length) 1:2.5–5.6 (3.9 ± 0.7; 16):1.3–3.0 (1.9 ± 0.4; 16).

Tentacles long, with slight basal swelling, not seen retracted into bulbs, at least 1,003 long, 22–35 (30 ± 3.8; 11; 20) wide at base, 26–38 (32 ± 3.4; 10; 17) wide at basal swelling, 12–26 (20 ± 3.6; 8; 15) wide in metabasal region.

Characteristic basal armature present (Figs. 9D, 9E, 10M), 78–97 (87 ± 6.9; 7; 11) long from base of tentacle to start of metabasal armature, consisting of 6–8 indistinct rows of hooks; hooks in posterior-most rows 1–3 uncinate with or without tips extending beyond hook base and with or without slight anterior base extensions to falcate, solid; billhooks in rows 4–8; billhooks falcate, erect, dorsoventrally flattened, solid or hollow, with and without short forward protrusions on lower surface, with recurved mucronate tips; mucronate tips solid or hollow; macrohooks absent.

Metabasal armature (Figs. 9A–9C, 10N–10P) heteroacanthous typical; hooks heteromorphous, solid, arranged in alternating ascending half-spiral rows of seven hooks each (Fig. 9B), reduced to six hooks per row more distally (Fig. 9C); rows originating with hooks 1(1′) on bothrial surface, terminating with hooks 7(7′) or 6(6′) in near single file on antibothrial surface; hooks 1(1′)–3(3′) not angled towards gap between hooks 1(1′). Hook files 1 and (1′) slightly separated, 4–9 (7 ± 1.4; 5; 10) apart. Hooks 1(1′) uncinate, with or without tips extending beyond hook base, 10–13 (12 ± 1.0; 4; 11) long, 6–9 (8 ± 1.1; 4; 11) high, base 8–11 (10 ± 0.8; 4; 11) long. Hooks 2(2′) falcate, with slightly recurved tips and slight anterior base extensions, 14–21 (17 ± 2.2; 5; 14) long, 7–13 (11 ± 1.6; 5; 14) high, base 6–10 (8 ± 1.3; 5; 14) long. Hooks 3(3′) falcate, with slightly recurved tips and slight anterior base extensions, 10–22 (18 ± 3.5; 5; 15) long, 8–16 (11 ± 2.1; 5; 15) high, base 5–7 (6 ± 0.7; 5; 15) long. Hooks 4(4′) falcate, with or without slightly recurved tips, with or without slightly slight anterior base extensions, 10–18 (15 ± 2.6; 4; 11) long, 6–14 (9 ± 2.3; 4; 11) high, base 4–6 (5 ± 0.6; 4; 11) long. Hooks 5(5′) falcate, with or without slightly recurved tips, with or without slightly slight anterior base extensions, 8–17 (12 ± 3.0; 5; 12) long, 4–11 (7 ± 2.7; 5; 12) high, base 4–5 (4 ± 0.5; 5; 12) long. Hooks 6(6′) falcate, with slightly recurved tips and slight anterior base extensions, 6–7 (7 ± 0.5; 3; 6) long, 3–5 (4 ± 0.8; 3; 6) high, base 2–4 (3 ± 0.8; 3; 6) long. Hooks 7(7′) falcate, with slightly recurved tips and slight anterior base extensions, 5–6 (n = 3; 4) long, 3 (n = 3; 4) high, base 3–4 (n = 3; 4) long.

Distal bothrial surfaces (Fig. 10C) with gladiate spinitriches and acicular and capilliform filitriches. Proximal bothrial surfaces near bothrial rims (Fig. 10D) with small gladiate spinitriches and acicular filitriches, away from bothrial rims (Fig. 10E) with few small gladiate spinitriches and acicular filitriches. Scolex proper at apex (Fig. 10G) and between bothria (Fig. 10F) with gladiate spinitriches and capilliform filitriches. Pars vaginalis (Fig. 10H), pars bulbosa (Fig. 10I), and strobila (Fig. 10J) with capilliform filitriches.

Proglottids acraspedote. Neck absent. Immature proglottids 5–10 (8 ± 1.4; 10) in number, wider than long, becoming longer than wide with maturity. Mature proglottids 1–2 (2 ± 0.5; 10) in number; terminal mature proglottids in mature worms 897–1,844 (1,305 ± 371.2; 7) long by 237–461 (306 ± 74.7; 7) wide. Gravid proglottids one (n = 3) in number; terminal gravid proglottids 1,065–1,527 (n = 3) long by 462–530 (n = 3) wide.

Testes 31–38 (36 ± 2.3; 8) in total number, 13–21 (17 ± 2.4; 8) pre-poral, 17–20 (18 ± 1.1; 8) post-poral, 31–111 (55 ± 20.0; 9; 27) long by 53–114 (80 ± 17.6; 7; 21) wide, in field from anterior margin of proglottid to ovary, slightly overlapping anterior margin of ovary, arranged in two columns (Fig. 8C), essentially in single layer. Vas deferens extending from mid-level of ovary to level anterior to cirrus sac, entering cirrus sac at its antero-medial margin, coiled primarily at level of and anterior to cirrus sac; external and internal seminal vesicles absent. Cirrus sac ovoid to elliptoid, 143–198 (169 ± 24.4; 8) long by 86–159 (123 ± 30.3; 10) wide, containing coiled cirrus; cirrus unarmed, thin-walled. Genital atrium absent. Genital pores separate, at same level, unilateral, 56–70% (62% ± 4.8%; 10) of proglottid length from posterior margin of proglottid in mature proglottids, 54–61% (n = 3) in gravid proglottids. Vagina thick-walled, weakly sinuous, extending from ootype along midline of proglottid to anterior margin of cirrus sac, then laterally at level of cirrus sac, terminating in female genital pore, greatly expanded when sperm-filled; vaginal sphincter absent; seminal receptacle present. Ovary terminal in proglottid, H-shaped in dorsoventral view, tetralobed in cross-section, 108–447 (257 ± 120.9; 10) long by 119–243 (186 ± 40.0; 8) wide, with lobulated margins; ovarian isthmus near center of ovary. Mehlis’ gland near posterior margin of ovary. Vitellarium follicular; follicles circumcortical, 10–51 (24 ± 10.7; 10; 30) long by 22–39 (30 ± 5.0; 8; 24) wide, extending entire length of proglottid, interrupted dorsally and ventrally by ovary, partially interrupted ventrally by terminal genitalia; post-ovarian vitelline follicles present. Uterus saccate, medial, dorsal to vagina, bifurcated at posterior end, extending from anterior margin of ovary to anterior margin of proglottid. Uterine duct not observed. Uterine pore absent. Excretory vessels four, arranged in one dorsal and one ventral pair on each lateral margin of proglottid. Eggs single, essentially spherical, 14–21 (n = 3) in diameter in situ, non-embryonated; polar filaments absent.

Type host: Pastinachus solocirostris Last, Manjaji & Yearsley, 2005 (Dasyatidae: Myliobatiformes).

Additional hosts: Rhinoptera neglecta Ogilby, 1912 (Rhinopteridae: Myliobatiformes); Aetobatus ocellatus (Kuhl, 1823) (Aetobatidae: Myliobatiformes); Pastinachus ater (Macleay, 1883) and Himantura australis (Ramsay & Ogilby, 1886) or Himantura leoparda Manjaji-Matsumoto & Last, 2008 (as H. uarnak) (Dasyatidae: Myliobatiformes).

Type locality: South China Sea, Malaysia: Sematan (01°48′15.45″N, 109°46′47.17″E), Sarawak.

Additional localities: Gulf of Carpentaria, Australia: Weipa (12°35′11″S, 141°42′34″E), Queensland. Indian Ocean, Australia: Nickol Bay (20°42′0″S, 116°51′0″E), Western Australia. Timor Sea, Australia: Dundee Beach (12°45’33"S, 130°21’7"E), Northern Territory, Fog Bay.

Site of infection: Spiral intestine.

Type specimens (verified): Holotype (ZRC.PLA.0409 [originally MZUM(P) 2012.04]), one paratype (ZRC.PLA.0411 [originally MZUM(P) 2012.06]), three paratypes (LRP 7844, LRP 7846–7847), 13 paratypes (AHC 35409, AHC 35412, AHC 35414 [mixed slide, see Table 3], AHC 35416, AHC 35441–35443, AHC 35445–35450), and one paratype (USNM 1400164 slides 1 and 3 [originally USNPC 105182]).

Type specimens (unverified): Five paratypes (AHC 35414 [mixed slide, see Table 3], AHC 35427, AHC 35428 [mixed slide, see Table 3], AHC 35433 [mixed slide, see Table 3], AHC 35444), one paratype (MZB Ca 174), and one paratype (USNM 1400163 slide 2 [originally USNPC 105181], see Table 3).

Voucher specimens: LRP 10658 (Schaeffner & Beveridge, 2014 [mixed slide, see Table 3]), LRP 10573–10600 (this study), LRP 10570–10572 (hologenophores; this study); AHC 36891–36893 (this study); QM G239457–G239462 (this study); USNM 1661573–1661575 (this study).

Museum specimens examined: All verified and unverified type specimens excepting one paratype (MZB Ca 174).

Remarks: This species was originally described as the only member of the genus Prochristianella Dollfus, 1946 to lack gland cells in the bulbs. The authors noted the morphological similarity to species of Rhinoptericola and Shirleyrhynchus in this regard but refrained from assigning the species to either genus because it possessed two, rather than four, bothria (Schaeffner & Beveridge, 2012b). Following the examination of type and new material it is now clear that the species possesses four bothria. In fact, the line drawing of the scolex and the scanning electron micrograph of the bothria in Schaeffner & Beveridge (2012b; figs. 4B and 6B, respectively) both seem to show four bothria. The possession of four bothria and pre-bulbar organs but a lack of gland cells in the bulbs immediately disqualifies this species from inclusion in Prochristianella and those features, as well as its tentacular armature, support the transfer of the species to Rhinoptericola. The inclusion of Rhinoptericola jensenae in the genus is further supported by its proglottid anatomy. Like the other species of Rhinoptericola with known proglottid anatomies, it possesses testes in two columns that overlap the ovary, separate male and female genital pores, a seminal receptacle, circumcortical vitelline follicles, and a uterus bifurcated at the posterior end (see Figs. 8A and 8C). Sequence data also support its inclusion in the genus (see results of phylogenetic analysis).

Unexpectedly, examination of the holotype and 63 of 64 paratypes of R. jensenae revealed that the type series is mixed and includes specimens with two distinct tentacular armatures. The holotype (ZRC.PLA.0409 [originally MZUM 2012.04]) and a subset of the paratypes possess a metabasal armature arranged in rows of seven hooks with rows of six hooks more distally on the tentacle, while the remaining paratypes possess a metabasal armature arranged in rows of nine hooks with rows of eight, and then seven, hooks more distally on the tentacle (see Table 3). These latter paratypes with the alternate morphology are described below as the new species Rhinoptericola schaeffneri n. sp. While most of the 63 paratypes examined were easily assigned to either R. jensenae or R. schaeffneri n. sp., six paratypes were problematic (i.e., AHC 35414, AHC 35427–35428, AHC 35433, AHC 35444, and USNM 1400163 slide 2). These paratypes either had multiple worms of different species mounted on the same slide (referred to as “mixed slides” above), worms with tentacles fully retracted or insufficiently everted to allow for identification to the level of species, or a combination thereof. Notes on these problematic specimens are given in Table 3. Identification as R. jensenae or R. schaeffneri n. sp. was not possible for the one unexamined paratype (i.e., MZB Ca 174); verification for this specimen is needed.

Rhinoptericola jensenae sensu stricto, as redescribed above, is easily distinguished from its congeners based on differences in overall size and features of the basal armature. Rhinoptericola jensenae differs from R. megacantha and R. butlerae in being smaller in total length (<6.5 mm vs >10 mm in R. megacantha and R. butlerae) and possessing fewer proglottids (<13 vs >22 in R. megacantha and R. butlerae). From R. panamensis and R. aetobatidis—for which features of the strobila are unknown—R. jensenae is readily differentiated based on its possession of a shorter scolex (<2 mm vs >2.6 mm in R. panamensis and R. aetobatidis) and shorter bulbs (<0.63 mm vs >1.3 mm in R. panamensis and R. aetobatidis). Rhinoptericola jensenae also lacks, rather than possesses, macrohooks in its characteristic basal armature, further distinguishing it from all four of its larger congeners.

The host species, host associations, and geographic localities reported above in the taxonomic summary for R. jensenae are based on new material and the type specimens examined that are morphologically consistent with the redescription. The revised type series comprises specimens from Rhinoptera neglecta (Rhinopteridae) from Australia and from three species of dasyatids: Pastinachus solocirostris from Malaysia, P. ater from Australia, and a species reported by Schaeffner & Beveridge (2012b) as Himantura uarnak from Australia. According to Last et al. (2016), the only members of the H. uarnak complex found in Western Australia, and thus the only members that are candidate hosts for R. jensenae, are Himantura australis and H. leoparda; verification is required. Based on new material, Aetobatus ocellatus is reported as a host for the first time. Rhinoptericola jensenae is thus restricted to the Indo-Pacific region, parasitizing batoids from Australia and Malaysia (see Table 3). Interestingly, the type specimens of R. jensenae deposited by Schaeffner & Beveridge (2012b) remain the only reports of this species from Malaysia. Examination of seven specimens of the type host P. solocirostris, two specimens of P. ater, and two specimens of Pastinachus gracilicaudus Last & Manjaji-Matsumoto, 2010 in search of R. jensenae yielded no additional material. Instead, specimens of P. solocirostris and P. ater were found to be parasitized by specimens of the new species, Rhinoptericola schaeffneri n. sp., described below. In fact, all new material of R. jensenae used in this study came from Australia (see Table 3).

Rhinoptericola schaeffneri n. sp.

urn:lsid:zoobank.org:act:EC3B77B4-BD65-4425-8EE9-DC9763B891DD

Figures 11–14, 15A and 15B

Synonym: Prochristianella jensenae Schaeffner & Beveridge, 2012b, in part.

Description (based on one gravid worm, five mature worms, one incomplete worm, five scoleces, cross-sections of one scolex and four scoleces prepared for SEM, and two voucher specimens [AHC 35423 and AHC 35424]):

Worms apolytic (Fig. 11A); mature worms 3.4–6.8 mm (4.4 ± 1.1; 7) long, gravid worms 2.6 mm (n = 1) long, maximum width at level of pars bothrialis, pars bulbosa, or terminal proglottid; proglottids 6–10 (7 ± 1.6; 6) in total number in mature and 7 (n = 1) in total number in gravid worms.

Scolex (Figs. 11B, 14A and 14B) acraspedote, elongate, slender, 938–1,619 (1,216 ± 189.3; 13) long, length:width ratio 2.9–6.7 (4.9 ± 1.1; 13):1. Pars bothrialis 171–327 (227 ± 45.0; 13) long by 204–302 (235 ± 28.9; 13) wide, with four bothria (Figs. 11B, 14A and 14B, 15A); bothria elliptoid, 135–246 (188 ± 34.3; 13; 35) long by 61–100 (87 ± 10.4; 8; 15) wide, with free lateral and posterior margins, arranged in dorsal and ventral pairs, not overlapping pars bulbosa; bothrial pits absent. Pintner’s cells absent. Pars vaginalis 536–1,022 (728 ± 165.4; 13) long by 116–208 (174 ± 24.8; 13) wide at midpoint; tentacle sheaths sinuous. Pars bulbosa 168–298 (203 ± 35.7; 13) long by 11–92 (31 ± 21.1; 13) wide at midpoint; bulbs very narrowly oblong, thick-walled, muscular, 360–573 (449 ± 54.8; 13; 38) long by 51–98 (67 ±11.0; 13; 37) wide; bulb length:width ratio 1:5.2–8.2 (6.8 ± 0.9; 13; 37):1; prebulbar organs present; gland cells inside bulbs absent; retractor muscles in bulbs 8–36 (15 ± 6.6; 13; 37) wide, originating at base of bulbs. Pars postbulbosa short, 11–92 (31 ± 21.1; 13) long. Scolex length ratio (pars bothrialis length:pars vaginalis length:pars bulbosa length) 1:2.4–4.6 (3.3 ± 0.7; 12):1.2–2.8 (2.2 ± 0.4; 12).

Tentacles long, with slight basal swelling, not seen retracted into bulbs, at least 535 long, 21–34 (27 ± 3.6; 10; 21) wide at base, 23–39 (29 ± 4.5; 10; 16) wide at basal swelling, 21–29 (24 ± 2.7; 10; 15) wide in metabasal region.

Characteristic basal armature present (Figs. 12C and 12D), 49–78 (64 ± 7.7; 10; 19) long from base of tentacle to start of metabasal armature, consisting of 5–6 indistinct rows of hooks; hooks in posterior-most row uncinate, with tips extending beyond hook base, solid; hooks in rows 2–3 on bothrial and internal surfaces uncinate, with tips extending beyond hook base, solid or hollow, and on antibothrial and external surfaces spiniform, solid; hooks in rows 4–6 on bothrial surface triangular with recurved tips, dorsoventrally flattened, solid or hollow, and on antibothrial, internal, and external surfaces billhooks; billhooks falcate, erect, dorsoventrally flattened, solid or hollow, with (Fig. 14N) and without (Fig. 14O) short forward protrusions on lower surface, with recurved mucronate tips; mucronate tips solid or hollow; macrohooks absent.

Metabasal armature (Figs. 12A, 12B, 12E, 13A–13D, 14K and 14L) heteroacanthous typical, heteromorphous; metabasal hooks solid or hollow, arranged in alternating ascending half-spiral rows of nine hooks immediately anterior to basal armature (Fig. 13A), reduced to eight (Figs. 13B, 13C, 14L) and then seven (Figs. 13C and 13D) hooks per row more distally; rows originating with hooks 1(1′) on bothrial surface, terminating with hooks 9(9′), 8(8′) or 7(7′) in near single file on antibothrial surface; hooks 1(1′)–3(3′) conspicuously angled towards gap between hooks 1(1′). Hook files 1 and (1′) slightly separated, 5–9 (6 ± 1.2; 8; 12) apart at base. Hooks 1(1′) occasionally with overlapping tips, uncinate, with tips extending beyond hook base, with or without anterior base extensions, 7–13 (11 ± 2.0; 7; 12) long, 4–8 (6 ± 1.1; 7; 12) high, base 4–10 (7 ± 2.2; 7; 12) long. Hooks 2(2′) uncinate with tips extending beyond hook base to falcate with slightly recurved tips and anterior base extensions, 11–19 (16 ± 2.5; 8; 13) long, 5–12 (8 ± 2.3; 8; 13) high, base 5–9 (6 ± 1.4; 8; 13) long. Hooks 3(3′) falcate, with recurved tips and anterior base extensions, 15–25 (18 ± 3.4; 8; 11) long, 5–14 (9 ± 2.4; 8; 11) high, base 4–7 (5 ± 1.0; 8; 11) long. Hooks 4(4′) falcate, with slightly recurved tips and anterior base extensions, 13–19 (16 ± 1.9; 7; 10) long, 4–12 (8 ± 2.4; 7; 10) high, base 2–6 (5 ± 1.2; 7; 10) long. Hooks 5(5′) hastate to falcate with slightly recurved tips, 11–16 (14 ± 1.9; 8; 11) long, 5–11 (8 ± 2.0; 8; 11) high, base 2–5 (4 ± 1.0; 8; 11) long. Hooks 6(6′) uncinate, with tips extending beyond hook base, 3–13 (10 ± 3.0; 8; 11) long, 4–10 (6 ± 2.3; 8; 11) high, base 3–12 (4 ± 2.6; 8; 11) long. Hooks 7(7′) uncinate with tips extending beyond hook base to falcate, 9–13 (11 ± 1.5; 5; 6) long, 6–10 (7 ± 1.6; 5; 6) high, base 3–5 (4 ± 0.6; 5; 6) long. Hooks 8(8′) uncinate with tips extending beyond hook base to falcate, 13–18 (n = 2; 3) long, 5–9 (n = 2; 3) high, base 4 (n = 2; 3) long. Hooks 9(9′) falcate, 7–11 (9 ± 1.2; 6; 8) long, 2–4 (3 ± 0.7; 4; 5) high, base 3–4 (3 ± 0.5; 6; 8) long.

Distal bothrial surfaces (Fig. 14C) with small gladiate spinitriches and acicular and capilliform filitriches. Proximal bothrial surfaces near bothrial rims (Fig. 14D) with gladiate spinitriches and capilliform filitriches, away from bothrial rims (Fig. 14E) with acicular filitriches. Scolex proper near and at apex (Fig. 14G) with acicular filitriches and between bothria (Fig. 14F) with capilliform filitriches. Pars vaginalis (Fig. 14H), pars bulbosa (Fig. 14I), and strobila (Fig. 14J) with acicular filitriches.

Proglottids acraspedote. Neck absent. Immature proglottids 4–8 (5 ± 1.3; 7) in number, wider than long, becoming longer than wide with maturity. Mature proglottids 1–2 (2 ± 0.5; 7) in number; terminal mature proglottids in mature worms 1,325–1,658 (1,465 ± 117.0; 7) long by 174–365 (262 ± 59.6; 8) wide. Gravid proglottids 1 (n = 1) in number; terminal gravid proglottids 1,605 (n = 1) long by 369 (n = 1) wide.

Testes 36–49 (43 ± 4.1; 8) in total number, 20–24 (23 ± 1.8; 8) pre-poral, 13–25 (20 ± 4.2; 8) post-poral, 33–88 (60 ± 15.8; 8; 23) long by 64–122 (83 ± 15.2; 6; 16) wide, in field from anterior margin of proglottid to ovary, slightly overlapping anterior margin of ovary, arranged in two columns (Fig. 11C), essentially in single layer. Vas deferens extending from mid-level of ovary to level slightly anterior to cirrus sac, entering cirrus sac at its antero-medial margin, coiled primarily anterior to cirrus sac; external and internal seminal vesicles absent. Cirrus sac ovoid to elliptoid, occasionally bent anteriorly, 128–190 (164 ± 22.6; 6) long by 84–170 (133 ± 27.2; 8) wide, containing coiled cirrus; cirrus unarmed, thin-walled. Genital atrium absent. Genital pores separate, at same level, unilateral, 48–65% (57% ± 7.0%; 8) of proglottid length from posterior margin of proglottid in mature proglottids and 66% (n = 1) in gravid proglottids. Vagina thick-walled, weakly sinuous, extending from ootype along midline of proglottid to anterior margin of cirrus sac, then laterally at level of cirrus sac, terminating in female genital pore, greatly expanded when sperm-filled; vaginal sphincter absent; seminal receptacle present. Ovary terminal in proglottid, H-shaped in dorsoventral view, tetralobed in cross-section, 128–190 (164 ± 22.6; 6) long by 84–170 (133 ± 27.2; 8) wide, with lobulated margins; ovarian isthmus near center of ovary. Mehlis’ gland near posterior margin of ovary. Vitellarium follicular; follicles circumcortical, 17–54 (25 ± 8.9; 7; 21) long by 24–46 (31 ± 7.4; 5; 15) wide, extending entire length of proglottid, interrupted dorsally and ventrally by ovary, partially interrupted ventrally by terminal genitalia; post-ovarian vitelline follicles present. Uterus saccate, medial, dorsal to vagina, bifurcated at posterior end, extending from anterior margin of ovary to anterior margin of proglottid. Uterine duct not observed. Uterine pore absent. Excretory vessels four, arranged in one dorsal and one ventral pair on each lateral margin of proglottid. Eggs single, essentially spherical, 13–16 (n = 3) in diameter in situ, non-embryonated; polar filaments absent.

Type host: Pastinachus solocirostris Last, Manjaji & Yearsley, 2005 (Dasyatidae: Myliobatiformes).

Additional hosts: Pastinachus ater (Macleay, 1883) and Pastinachus gracilicaudus Last & Manjaji-Matsumoto, 2010 (Dasyatidae: Myliobatiformes).

Type locality: South China Sea, Malaysia: Sematan (01°48′15.45″N, 109°46′47.17″E), Sarawak.

Additional localities: Makassar Strait, Indonesia: Muara Pasir (01°45′58.92″S, 116°23′36.09″E), East Kalimantan; and Sei Kerbau (00°31′44.50″S, 117°09′32.90″E), East Kalimantan. South China Sea, Malaysia: Mukah (02°53′52.16″N, 112°05′44.12″E), Sarawak. Sulu Sea, Malaysia: Kampung Tetabuan (06°01′10.32″N, 117°42′14.76″E), Sabah.

Site of infection: Spiral intestine.

Type specimens: Holotype (MZUM[P] 2021.1 [H]), two paratypes (MZUM[P] 2021.2 [P]–2021.3 [P]), five paratypes (LRP 10602–10656), one paratype (SBC-P-00077), one paratype (MZB Ca 211), and four paratypes (USNM 1661588–1661591).

Voucher specimens: AHC 35408, AHC 35410–11, AHC 35413, AHC 35415, AHC 35417–26, AHC 35428 (mixed slide, see Table 3), AHC 35429–32, AHC 35433 (mixed slide, see Table 3), AHC 35434–40; MZB Ca 168–75; LRP 7843, LRP 7845, LRP 7848–9; USNM 1400163 slide 1 (originally USNPC 105181), USNM 1400164 slides 2, 4, and 5 (originally USNPC 105182); and ZRC.PLA.0410 (originally MZUM[P] 2012.05), ZRC.PLA.0412–3 (originally MZUM[P] 2012.07–8) (all originally deposited as paratypes of Prochristianella jensenae; Schaeffner & Beveridge, 2012b); LRP 10657 (Schaeffner & Beveridge, 2014), LRP 10658 (Schaeffner & Beveridge, 2014 [mixed slide, see Table 3]); LRP 10601 (hologenophore, this study).

Museum specimens examined: All voucher specimens.

Etymology: This species is named for Dr. Bjoern C. Schaeffner for his contributions to trypanobatoid taxonomy.

Remarks: Rhinoptericola schaeffneri n. sp. is erected for new material and the paratypes of Prochristianella jensenae that were found to not be conspecific with R. jensenae as redescribed above. Rhinoptericola schaeffneri n. sp. can be distinguished from all species of Rhinoptericola—including R. jensenae—by its unique metabasal armature: R. schaeffneri n. sp. possesses nine hooks per row immediately anterior to the basal armature (see Fig. 13A), diminishing to eight, and then seven, hooks per row more distally on the tentacle (see Figs. 13B–13D), while its congeners possess either seven hooks per principal row (e.g., see Fig. 3C), or seven hooks per principal row proximally, diminishing to six hooks per principal row more distally on the tentacle (e.g., see Figs. 9B and 9C). Rhinoptericola schaeffneri n. sp. is similarly unique in terms of the shape and size of its metabasal hooks along a row: in R. schaeffneri n. sp., hooks 1(1′)–3(3′) are consistently angled towards the space between hook files 1 and (1′), and hooks gradually diminish in size along a row (see Figs. 12, 13, 14K and 14L). In the other five species of Rhinoptericola, hooks 1(1′)–3(3′) are not angled towards the space between hook files 1 and (1′), and there is both a stark physical separation and change in hook size between hooks 5(5′) and 6(6′) (e.g., see Figs. 10O and 10P for R. jensenae).

Rhinoptericola schaeffneri n. sp. can be distinguished further from R. megacantha and R. butlerae based on its shorter total length (<7 mm vs >10 mm in R. megacantha and R. butlerae) and fewer number of proglottids (<11 vs >22 in R. megacantha and R. butlerae), and from R. panamensis and R. aetobatidis based on its shorter scolex (<1.7 mm vs >3.8 mm in R. panamensis and R. aetobatidis) and shorter bulbs (<0.6 mm vs >1.9 mm in R. panamensis and R. aetobatidis). This new species is similar in size to R. jensenae but the two can be further distinguished based on metabasal hook shape: in Rhinoptericola schaeffneri n. sp., metabasal hooks 5(5′)–7(7′) are thinner and more elongate than those in R. jensenae (see Figs. 14L vs 10O). Rhinoptericola schaeffneri n. sp. is only known from species of cowtail rays (genus Pastinachus Forsskål, 1775) and only from the waters off Malaysia and Indonesia.

It should be noted that three of the paratypes of Prochristianella jensenae (i.e., AHC 35414, AHC 35428, and AHC 35433) and one voucher specimen (i.e., LRP 10658) consist of slides with specimens confirmed as R. schaeffneri mounted alongside worms of other species (including, for AHC 35414 and LRP 10658, specimens of R. jensenae). Notes on these specimens are given in Table 3.

Rhinoptericola mozambiquensis n. sp.

urn:lsid:zoobank.org:act:958674CF-3029-4E37-A709-289E0354E2DF

Figures 15C–15H, 16–18

Description (based on five gravid worms, 16 mature worms, one immature worm, cross-sections of one scolex and one partial strobila, and three scoleces and one partial strobila prepared for SEM):

Worms apolytic (Fig. 16A); mature worms 2.6–4.8 mm (3.7 ± 0.6; 16) long, gravid worms 1.6–5.9 mm (4.2 ± 1.7; 5) long, maximum width at level of pars bothrialis or terminal proglottid; proglottids 5–10 (7 ± 1.3; 16) in total number in mature and 6–10 (9 ± 1.6; 5) in total number in gravid worms.

Scolex (Figs. 16A, 16B, 18A) acraspedote, elongate, slender, 1,122–1,862 (1,389 ± 206.6; 22) long, length:width ratio 2.4–5.6 (3.5 ± 0.9; 19):1. Pars bothrialis 192–380 (251 ± 51.8; 18) long by 215–357 (277 ± 46.6; 19) wide, with four bothria (Figs. 15D, 16A, 16B, 18A); bothria narrowly elliptoid to very deeply ovoid, 133–273 (194 ± 33.2; 20; 54) long by 55–164 (110 ± 23.2; 16; 42) wide, with free lateral and posterior margins, arranged in dorsal and ventral pairs, not overlapping pars bulbosa; bothrial pits absent. Pintner’s cells absent. Pars vaginalis 724–1,371 (932 ± 179.9; 22) long by 120–225 (162 ± 25.3; 22) wide at midpoint; tentacle sheaths sinuous. Pars bulbosa 379–577 (461 ± 54.9; 22) long by 160–237 (191 ± 19.1; 22) wide at midpoint; bulbs very narrowly oblong, thick-walled, muscular, 343–565 (452 ± 50.5; 21; 66) long by 50–95 (68 ± 10.1; 22; 66) wide; bulb length:width ratio 4.4–11.0 (6.7 ± 1.2; 22; 64):1; prebulbar organs present; gland cells inside bulbs absent; retractor muscles in bulbs 10–23 (15 ± 2.8; 22; 66) wide, originating at base of bulbs. Pars postbulbosa short or absent, 10–18 (n = 3) long when present. Scolex length ratio (pars bothrialis length:pars vaginalis length:pars bulbosa length) 1:2.9–4.6 (3.9 ± 0.5; 18):1.2–2.4 (1.9 ± 0.3; 18).

Tentacles long, with slight basal swelling, occasionally retracted into bulbs, at least 1,007 long, 19–48 (29 ± 5.2; 21; 43) wide at base, 21–38 (31 ± 3.8; 19; 34) wide at basal swelling, 15–34 (21 ± 3.9; 19; 36) wide in metabasal region.

Characteristic basal armature present (Figs. 17D, 17E, 18P), 71–133 (91 ± 12.3; 17; 26) long from base of tentacle to start of metabasal armature, consisting of 6–7 indistinct rows of hooks; hooks in posterior-most rows 1–3 uncinate with or without tips extending beyond hook base and with or without slight anterior base extensions to falcate, solid; hooks in rows 4–7 on bothrial surface triangular, dorsoventrally flattened, with tips extending well beyond hook base, solid, and on antibothrial, internal, and external surfaces billhooks; billhooks falcate, erect, dorsoventrally flattened, solid or hollow, with recurved mucronate tips; mucronate tips solid or hollow; macrohooks absent.

Metabasal armature (Figs. 17A–17C, 17F, 18M–18O) heteroacanthous typical; hooks heteromorphous, solid, arranged in alternating ascending half-spiral rows of seven hooks each, reducing to six hooks each more distally (Figs. 17C, 18O); rows originating with hooks 1(1′) on bothrial surface, terminating with hooks 7(7′) or 6(6′) in near single file on antibothrial surface; hooks 1(1′)–3(3′) not angled towards space between hook files 1 and (1′). Hook files 1 and (1′) slightly separated, 3–9 (5 ± 1.3; 14; 23) apart. Hooks 1(1′) uncinate, with or without tips extending beyond hook base, 8–15 (13 ± 1.8; 15; 29) long, 6–15 (8 ± 1.9; 15; 29) high, base 6–11 (9 ± 1.2; 15; 29) long. Hooks 2(2′) falcate, with slightly recurved tips and slight anterior base extensions, 14–21 (18 ± 1.8; 17; 30) long, 8–15 (12 ± 2.0; 17; 30) high, base 6–11 (8 ± 1.2; 17; 30) long. Hooks 3(3′) falcate, with slightly recurved tips and slight anterior base extensions, 14–24 (20 ± 2.4; 18; 33) long, 9–18 (13 ± 2.3; 18; 33) high, base 5–9 (6 ± 1.1; 18; 33) long. Hooks 4(4′) falcate, with or without slightly recurved tips, with or without slightly slight anterior base extensions, 14–21 (17 ± 2.0; 17; 23) long, 4–16 (10 ± 2.5; 17; 23) high, base 4–6 (6 ± 0.6; 17; 23) long. Hooks 5(5′) falcate, with or without slightly recurved tips, with or without slight anterior base extensions, 13–19 (17 ± 1.7; 13; 15) long, 5–15 (10 ± 2.5; 13; 15) high, base 5–7 (6 ± 0.7; 13; 15) long. Hooks 6(6′) falcate, with slightly recurved tips and slight anterior base extensions, 6–8 (7 ± 0.8; 10; 13) long, 3–5 (4 ± 0.8; 10; 13) high, base 3–5 (3 ± 0.7; 10; 13) long. Hooks 7(7′) falcate, with slightly recurved tips and slight anterior base extensions, 6–8 (7 ± 0.8; 9; 11) long, 2–5 (4 ± 0.8; 9; 11) high, base 3–5 (4 ± 0.8; 9; 11) long.

Distal bothrial surfaces (Fig. 18B) with large gladiate spinitriches and acicular to capilliform filitriches. Proximal bothrial surfaces near bothrial rims (Fig. 18C) with small gladiate spinitriches and capilliform filitriches, away from bothrial rims (Fig. 18D) with capilliform filitriches only. Scolex proper near and at apex (Fig. 18F) with acicular to capilliform filitriches and between bothria (Fig. 18E) with small gladiate spinitriches and acicular to capilliform filitriches. Pars vaginalis (Fig. 18G), pars bulbosa (Fig. 18H), and strobila (Fig. 18I) with capilliform filitriches.

Proglottids acraspedote. Neck absent. Immature proglottids 4–9 (6 ± 1.4; 21) in number, wider than long, becoming longer than wide with maturity. Mature proglottids 0–2 (1 ± 0.5; 21) in number; terminal mature proglottids in mature worms 708–1,562 (1,101 ± 229.5; 16) long by 232–419 (306 ± 53.0; 16) wide. Gravid proglottids one (n = 5) in number; terminal gravid proglottids 1,407–1,970 (1,735 ± 261.1; 5) long by 427–690 (n = 4) wide.

Testes 23–35 (29 ± 2.8; 16) in total number, 11–18 (15 ± 1.7; 16) pre-poral, 12–18 (14 ± 1.7; 16) post-poral, 38–114 (64 ± 17.9; 18; 45) long by 46–118 (88 ± 14.4; 15; 36) wide, in field from anterior margin of proglottid to ovary, slightly overlapping anterior margin of ovary, arranged in two columns (Fig. 16C), essentially in single layer (Fig. 15F). Vas deferens extending from near mid-level of ovary to slightly anterior to anterior margin of cirrus sac, entering cirrus sac at its antero-medial margin; external and internal seminal vesicles absent. Cirrus sac ovoid to elliptoid, 164–206 (183 ± 10.7; 12) long by 84–178 (133 ± 23.9; 16) wide, containing coiled cirrus; cirrus unarmed, thin-walled. Genital atrium absent. Genital pores separate (Figs. 15E, 18L), at same level, unilateral, 56–70% (64% ± 3.8%; 16) of proglottid length from posterior margin of proglottid in mature proglottids and 58–65% (n = 3) in gravid proglottids. Vagina thick-walled, weakly sinuous, extending from ootype along midline of proglottid to anterior margin of cirrus sac, then laterally at level of cirrus sac, terminating in female genital pore, greatly expanded when sperm-filled; vaginal sphincter absent; seminal receptacle present. Ovary terminal in proglottid, H-shaped in dorsoventral view, tetralobed in cross-section (Fig. 15H), 187–427 (277 ± 62.3; 15) long by 156–266 (193 ± 36.3; 11) wide, with lobulated margins; ovarian isthmus near center of ovary. Mehlis’ gland near posterior margin of ovary. Vitellarium follicular; follicles circumcortical, 16–48 (30 ± 7.8; 20; 50) long by 18–64 (34 ± 8.4; 17; 42) wide, extending entire length of proglottid, interrupted dorsally and ventrally by ovary and partially interrupted ventrally by terminal genitalia; post-ovarian vitelline follicles present. Uterus saccate, medial, dorsal to vagina, bifurcated at posterior end (Fig. 15H), extending from anterior margin of ovary to anterior margin of proglottid. Uterine duct not observed. Uterine pore absent. Excretory vessels four, arranged in one dorsal and one ventral pair on each lateral margin of proglottid. Eggs single, essentially spherical, 7–18 (12 ± 4.6; 2; 6) in diameter in situ, non-embryonated; polar filaments absent.

Type host: Rhinoptera jayakari Boulenger, 1895 (Rhinopteridae: Myliobatiformes).

Type locality: Mozambique Channel, Mozambique: Tofo (23°47′33.02″S, 35°31′16.38″E), Inhambane.

Site of infection: Spiral intestine.

Type specimens: Holotype (USNM 1661599), 14 paratypes (USNM 1661596–1661598, USNM 1661600–1661610), and 11 paratypes (LRP 10661–10720).

Voucher specimens: LRP 10659–10660 (hologenophores, this study).

Etymology: This species is named for its country of origin, Mozambique.

Remarks: Rhinoptericola mozambiquensis n. sp. is distinguished from R. megacantha and R. butlerae based on its shorter total length (<6 mm vs >10 mm in R. megacantha and R. butlerae) and fewer proglottids (<11 vs >22 in R. megacantha and R. butlerae). It is distinguished from R. panamensis and R. aetobatidis based on its shorter scolex (<1.9 mm vs >3.8 mm in R. panamensis and R. aetobatidis) and shorter bulbs (<0.6 mm vs >1.9 mm in R. panamensis and R. aetobatidis). This new species can also be distinguished from its four larger congeners by its lack of macrohooks in the basal armature; R. megacantha, R. butlerae, R. panamensis, and R. aetobatidis all possess two to four macrohooks in the basal armature. Though similar in overall size, R. mozambiquensis n. sp. has a unique metabasal armature as compared to R. schaeffneri. It possesses seven hooks per principal row diminishing to six hooks per principal row more distally, while R. schaeffneri possesses nine hooks per principal row immediately anterior to the basal armature, diminishing to eight, and then seven, hooks per row more distally.

This new species is most morphologically similar to R. jensenae. Both species possess a metabasal armature with seven hooks per principal row diminishing to six hooks per row more distally, a basal armature of similar length that lacks macrohooks, and similar total lengths, scolex lengths, numbers of proglottids, and numbers of testes. Rhinoptericola mozambiquensis n. sp. is distinguished from R. jensenae, however, based on the shape of hooks in the anterior portion of the basal armature. In this tentacle region, both species possess billhooks that are falcate, erect, and dorsoventrally flattened with recurved mucronate tips; however, in R. jensenae, a subset of these billhooks have short forward protrusions on their lower surface (i.e., are “can opener-shaped”; see Figs. 9D, 9E, 10K–10M)—a feature conspicuously absent in R. mozambiquensis n. sp. (see Figs. 17D, 17E, 18K, 18P). Additionally, R. mozambiquensis n. sp. possesses triangular, solid, dorsoventrally flattened hooks with tips extending well beyond the hook base on the bothrial surface of its basal armature (see Figs. 17D, 18J, 18P) which are absent in R. jensenae (see Fig. 9D). Molecular data similarly support the two as separate species (see results of phylogenetic analysis). Unlike its congeners, R. mozambiquensis n. sp. is described from only a single species of host and has a geographic distribution restricted to the waters off Mozambique.

Rhinoptericola hexacantha n. sp.

urn:lsid:zoobank.org:act:0D1C299F-11FF-415D-B2BA-88BC60FD5E1E

Figures 19–21

Description (based on eight mature worms, two immature worms, one detached mature proglottid, cross-sections of one scolex, and two scoleces prepared for SEM):

Worms euapolytic (Fig. 19A); 2.5–6.4 mm (3.7 ± 1.4; 8) long, maximum width at level of pars bothrialis; proglottids 4–10 (7 ± 1.9; 9) in total number.

Scolex (Figs. 19B, 21A and 21B) acraspedote, elongate, slender, 686–1,368 (973 ± 238.6; 10) long, length:width ratio 1.6–3.2:1 (n = 4). Pars bothrialis 153–291 (223 ± 47.6; 7) long by 227–362 (289 ± 48.1; 7) wide, with four bothria (Figs. 19A, 19B, 21A, 21B); bothria elliptoid to deeply ovoid, 123–219 (177 ± 26.0; 9; 21) long by 75–124 (96 ± 14.2; 7; 15) wide, with free lateral and posterior margins, arranged in dorsal and ventral pairs, not overlapping pars bulbosa; bothrial pits absent. Pintner’s cells absent. Pars vaginalis 383–1,045 (551 ± 202.9; 10) long by 139–240 (205 ± 37.9; 10) wide at midpoint; tentacle sheaths sinuous. Pars bulbosa 326–699 (472 ± 117.4; 10) long by 144–259 (203 ± 32.8; 10) wide at midpoint; bulbs very narrowly oblong, thick-walled, muscular, 285–610 (457 ± 84.5; 10; 28) long by 50–102 (74 ± 12.5; 10; 27) wide; bulb length:width ratio 3.8–12.1 (6.4 ± 2.1; 10; 25):1; prebulbar organs present; gland cells inside bulbs absent; retractor muscles in bulbs 8–31 (14 ± 5.6; 10; 29) wide, originating at base of bulbs. Pars postbulbosa short or absent, 7–8 (n = 2) long when present. Scolex length ratio (pars bothrialis length:pars vaginalis length:pars bulbosa length) 1:2.0–4.3 (2.7 ± 0.8; 7):1.7–2.9 (2.2 ± 0.5; 7).

Tentacles long, with slight basal swelling, occasionally retracted into bulbs, at least 360 long, 25–32 (29 ± 2.5; 3; 6) wide at base, 26–37 (33 ± 4.5; 6; 3) wide at basal swelling, 16–24 (20 ± 3.0; 3; 6) wide in metabasal region.

Characteristic basal armature present (Figs. 20C, 20D, 21N), 84–95 (89 ± 4.9; 3; 5) long from base of tentacle to start of metabasal armature, consisting of 5–7 indistinct rows of hooks; hooks in posterior-most 2–3 rows uncinate, solid; anterior 4–5 rows with spiniform hooks and billhooks; billhooks falcate, erect, dorsoventrally flattened, solid or hollow, with recurved mucronate tips; mucronate tips solid or hollow; macrohooks absent.

Metabasal armature (Figs. 20A, 20B, 20E, 21K–21M) heteroacanthous typical; hooks heteromorphous, solid, arranged in alternating ascending half-spiral rows of six hooks each; rows originating with hooks 1(1′) on bothrial surface, terminating with hooks 6(6′) in near single file on antibothrial surface; hooks 1(1′)–3(3′) not angled towards the space between hooks files 1 and (1′). Hook files 1 and (1′) slightly separated, 3–6 (n = 3) apart. Hooks 1(1′) uncinate, slightly recurved, 10–13 (n = 3) long, 6–9 (n = 3) high, base 6–11 (n = 3) long. Hooks 2(2′) falcate, with recurved tips, 12–19 (n = 3) long, 8–12 (n = 3) high, base 5–8 (n = 3) long. Hooks 3(3′) falcate, with recurved tips and anterior base extensions, 13–22 (n = 3) long, 9–14 (n = 3) high, base 4–7 (n = 3) long. Hooks 4(4′) falcate, with recurved tips and anterior base extensions, 11–20 (n = 3) long, 6–11 (n = 3) high, base 4–5 (n = 3) long. Hooks 5(5′) falcate to uncinate, 6–7 (n = 3) long, 3–4 (n = 3) high, base 2–4 (n = 3) long. Hooks 6(6′) falcate to uncinate, 5–7 (n = 3) long, 3–4 (n = 3) high, base 2–3 (n = 3) long.

Distal bothrial surfaces (Fig. 21C) with large gladiate spinitriches and acicular to capilliform filitriches. Proximal bothrial surfaces near bothrial rims (Fig. 21D) with small gladiate spinitriches and acicular to capilliform filitriches, away from bothrial rims (Fig. 21E) with acicular to capilliform filitriches only. Scolex proper near and at apex (Fig. 21G) with small gladiate spinitriches and capilliform filitriches, between bothria with acicular to capilliform filitriches only (Fig. 21F). Pars vaginalis (Fig. 21H), pars bulbosa (Fig. 21I), and strobila (Fig. 21J) with capilliform filitriches.

Proglottids acraspedote. Neck absent. Immature proglottids 3–8 (5 ± 1.6; 9) in number, wider than long, becoming longer than wide with maturity. Mature proglottids 1–2 (1 ± 0.5; 8) in number; terminal mature proglottids 820–1,649 (1,153 ± 260.7; 7) long by 195–288 (227 ± 38.3; 7) wide, free mature proglottids 1,303 (n = 1) long by 328 (n = 1) wide. Gravid proglottids not observed.

Testes 30–35 (32 ± 2.1; 7) in total number, 16–19 (17 ± 1.1; 7) pre-poral, 12–17 (15 ± 1.8; 7) post-poral, 37–93 (58 ± 14.7; 7; 21) long by 53–98 (72 ± 10.9; 7; 18) wide, in field from anterior margin of proglottid to ovary, slightly overlapping anterior margin of ovary, arranged in two columns (Fig. 19C), essentially in single layer. Vas deferens extending from near mid-level of ovary to slightly anterior of anterior margin of cirrus sac, entering cirrus sac at its antero-medial margin, coiled primarily anterior to cirrus sac; external and internal seminal vesicles absent. Cirrus sac ovoid to elliptoid, 106–181 (129 ± 27.7; 6) long by 82–154 (121 ± 26.8; 7) wide, containing coiled cirrus; cirrus unarmed, thin-walled, 185 long (n = 1) by 72 wide (n = 1) at base, 26 wide (n = 1) at tip when everted. Genital atrium absent. Genital pores separate, at same level, unilateral, 55–64% (60% ± 3.0%; 8) of proglottid length from posterior margin of proglottid. Vagina thick-walled, weakly sinuous, extending from ootype along midline of proglottid to anterior margin of cirrus sac, then laterally at level of cirrus sac, terminating in female genital pore, greatly expanded when sperm-filled; vaginal sphincter absent; seminal receptacle present. Ovary terminal in proglottid, H-shaped in dorsoventral view, tetralobed in cross-section, 180–379 (242 ± 69.1; 7) long by 114–241 (160 ± 53.8; 7) wide, with lobulated margins; ovarian isthmus near center of ovary. Mehlis’ gland near posterior margin of ovary. Vitellarium follicular; follicles circumcortical, 16–38 (29 ± 5.4; 8; 24) long by 21–47 (32 ± 7.0; 7; 21) wide, extending entire length of proglottid, interrupted dorsally and ventrally by ovary, partially interrupted ventrally by terminal genitalia; post-ovarian vitelline follicles present. Uterus saccate, medial, dorsal to vagina, bifurcated at posterior end, extending from anterior margin of ovary to anterior margin of proglottid. Uterine duct not observed. Uterine pore absent. Excretory vessels four, arranged in one dorsal and one ventral pair on each lateral margin of proglottid. Eggs not observed.

Type host: Rhinoptera steindachneri Evermann & Jenkins, 1891 (Rhinopteridae: Myliobatiformes).

Type locality: Gulf of California, Mexico: Loreto (25°49′52″N, 111°19′38″W), Baja California Sur.

Additional localities: Gulf of California, Mexico: Bahia de Los Angeles (28°59′9″N, 113°32′53″W), Baja California; Puertecitos (30°20′58″N, 114°38′22″W), Baja California; and Santa Rosalia (27°19′51″N, 112°15′30″W), Baja California Sur.

Site of infection: Spiral intestine.

Type specimens: Holotype (CNHE 11612), three paratypes (CNHE 11613–11614), five paratypes (LRP 10722–10772), and four paratypes (USNM 1661592–1661595).

Voucher specimen: LRP 10721 (hologenophore, this study).

Etymology: This species is named for its possession of six hooks per principal row in the metabasal armature throughout the tentacle length, a unique feature among species of Rhinoptericola.

Remarks: Rhinoptericola hexacantha n. sp. differs from all known species of Rhinoptericola in consistently having six hooks per principal row in the metabasal armature vs having seven hooks per row proximally and six hooks per row more distally (R. jensenae and R. mozambiquensis) or seven or more hooks per row (R. megacantha, R. butlerae, R. panamensis, R. aetobatidis, and R. schaeffneri). It is further distinguished from the species of Rhinoptericola for which features of the strobila are known (i.e., R. megacantha, R. butlerae, R. jensenae, R. schaeffneri, and R. mozambiquensis) in being euapolytic rather than apolytic. Rhinoptericola hexacantha n. sp. is shorter in total length than R. megacantha and R. butlerae (<6.5 mm vs >10 mm in R. megacantha and R. butlerae) and has a shorter scolex than R. panamensis and R. aetobatidis (<1.4 mm vs >3.8 mm in R. panamensis and R. aetobatidis). It also lacks macrohooks in the basal armature, further distinguishing it from its larger congeners (i.e., R. megacantha, R. butlerae, R. panamensis, and R. aetobatidis) which possess basal armatures with two to four macrohooks.

Rhinoptericola hexacantha n. sp. is further distinguished from R. jensenae, R. schaeffneri, and R. mozambiquensis by the shape of hooks in the anterior portion of the basal armature. In this region of the tentacle, R. hexacantha n. sp. possesses only billhooks that are falcate, erect, and dorsoventrally flattened with recurved mucronate tips, while R. jensenae, R. schaeffneri, and R. mozambiquensis each possess billhooks of this shape in addition to either billhooks with short forward protrusions on their lower surface (i.e., “can opener-shaped” billhooks in R. jensenae and R. schaeffneri), or triangular, solid, dorsoventrally flattened hooks with tips extending well beyond the hook base (in R. mozambiquensis). Rhinoptericola hexacantha n. sp. has a geographic distribution restricted to the Gulf of California, and like R. mozambiquensis, is known from only one species of cownose ray host (in this case, Rhinoptera steindachneri).

Phylogenetic analysis

For 29 of the 32 specimens sequenced, 1,411–1,426 bp of 28S were generated; for GenBank nos. OL412709 (R. butlerae), OL412737 (R. schaeffneri), and OL412738 (R. mozambiquensis), 1,246 bp, 841 bp, and 1,131 bp were generated, respectively (see Table 2). The initial matrix of 182 sequences, including sequences from six outgroup specimens, was trimmed to a maximum length of 1,510 bp. PRANK produced an alignment of 1,836 positions, including 946 invariable sites and 890 variable sites, which was used for tree searching and bootstrapping analyses. The resulting most likely topology with nodal support provided as bootstrap values (BS) is shown in Fig. 22 with the monophyletic Trypanoselachoida collapsed. For the MUSCLE alignment of 1,429 bp of 28S data for only the 32 specimens of Rhinoptericola sequenced herein and the single 28S sequence for R. megacantha available in GenBank (DQ642792), intraspecific divergence ranged from 0–2 bp and interspecific divergence ranged from 20–70 bp (excluding ambiguous base calls, see Table 4).

The genus Rhinoptericola was recovered as a monophyletic group (BS 100) sister to Nataliella marcelli; thus, a monophyletic Rhinoptericolidae were recovered, though the two genera are united with relatively low nodal support (BS 81). For the four species of Rhinoptericola for which replicate individuals could be sequenced, all replicates were recovered as reciprocally monophyletic groups with high nodal support (BS 96 or 100). Rhinoptericola megacantha and R. butlerae (both relatively large species with total lengths >10 mm) were recovered as a monophyletic group (BS 100) sister to the small species R. hexacantha (total length <6.5 mm; BS 92); the remaining three small species (i.e., R. jensenae, R. schaeffneri, and R. mozambiquensis; total lengths <6.8 mm) formed a monophyletic group (BS 88).

Discussion

Conclusions

In terms of broader contributions to the field of trypanorhynch taxonomy and systematics, this study: (1) increases the number of species of Rhinoptericola from one to eight and the number of species of rhinoptericolids from two to nine, and greatly expands known host associations and geographic distributions for species of Rhinoptericola; (2) corrects and simplifies the interpretation of hook arrangement in species of Rhinoptericola; (3) represents the first comprehensive assessment of the degree of intra- vs interspecific variation in 28S for elasmobranch tapeworms demonstrating relaxed host specificity; (4) demonstrates the importance of integrating scolex and proglottid anatomy and morphology (as seen with light microscopy) with both data on tentacular armature and hook shape (as seen with SEM) and 28S data for trypanorhynch species delimitation; and (5) provides a novel schematic to streamline communication of the tentacular surface presented in SEMs and line drawings and make clear the authors’ interpretations of these important images. This methodological framework can be readily applied to the study of other groups of trypanorhynchs in need of revision towards a stable classification for the group, and ultimately, elucidation of its evolutionary history.

The following taxonomic actions were taken herein: (1) Shirleyrhynchus became a junior synonym of Rhinoptericola and all three species in the genus Shirleyrhynchus were transferred to the genus Rhinoptericola creating the new combinations Rhinoptericola aetobatidis, Rhinoptericola butlerae, and Rhinoptericola panamensis; (2) the family name Shirleyrhynchidae became a junior synonym of the family name Rhinoptericolidae; (3) Cetorhinicola acanthocapax, formerly of the Shirleyrhynchidae, is now considered a taxon incertae sedis within the superfamily Eutetrarhynchoidea; (4) the species Prochristianella jensenae was transferred to the genus Rhinoptericola, creating the new combination Rhinoptericola jensenae; (5) the type series of Proc. jensenae was split into two species: R. jensenae was redescribed based on the holotype, a subset of paratypes, and new material, and the new species Rhinoptericola schaeffneri was described based on the subset of paratypes of Proc. jensenae not considered conspecific with R. jensenae and new material; and (6) the new species Rhinoptericola mozambiquensis and Rhinoptericola hexacantha were described based on new material.

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