A new species of Proceratophrys Miranda-Ribeiro, 1920 (Anura, Odontophrynidae) from Southern Amazonia, Brazil

Introduction

Integrative taxonomic approaches are considered paramount to describe new species (Padial et al., 2010). This is especially true for taxa in megadiverse regions, where new species are usually found (Toledo & Batista, 2012; Moura et al., 2018), and within speciose genera, where species are often misidentified (Fouquet et al., 2007). Such a diversity scenario occurs in Amazonia, the largest tropical forest in the world, where many anuran species are still unnamed (Funk, Caminer & Ron, 2011; Rojas et al., 2018). Many Amazonian species are considered widespread, but studies using integrative approaches have unveiled new species and lineages covering much smaller areas than previously known (Fouquet et al., 2007; Funk, Caminer & Ron, 2011; Ferrão et al., 2016). Focusing taxonomic efforts to reveal this hidden diversity is important for properly documenting Earth’s biodiversity (Brito, 2010) and for illuminating diversification patterns. Undescribed species occurring in megadiverse regions may also face threats that lead them to become extinct before they can be formally described (Lees & Pimm, 2015), especially in regions where anthropogenic disturbance has drastically changed the landscape, such as with hydroelectric dams in Amazonia (Silva et al., 2018).

The Amazon forest harbors several populations of Proceratophrys Miranda-Ribeiro, 1920, which are historically identified as P. concavitympanum Giaretta, Bernarde & Kokubum, 2000 or P. rondonae Prado & Pombal, 2008 (Prado & Pombal, 2008; Bernardo, Matiazzi & Guerra-Fuentes, 2012). These species are easily distinguished because P. rondonae has well-developed palpebral appendages, which are not present in P. concavitympanum (Prado & Pombal, 2008). Therefore, all populations of Proceratophrys across Amazonia without developed eyelid appendages have been called P. concavitympanum, yielding a widespread distribution for this species (Bernardo, Matiazzi & Guerra-Fuentes, 2012). Nevertheless, only two populations identified as P. concavitympanum have molecular data available on GenBank: one from a Cerrado region (Palmas municipality, Tocantins state; Amaro, Pavan & Rodrigues, 2009) and the other from Amazonia (Aripuanã municipality, Mato Grosso state; Mângia et al., 2018). The population from Palmas is more closely related to P. ararype from relictual forests within Caatinga in northeastern Brazil (Mângia et al., 2018). Once the authors found that individuals from Palmas are not P. concavitympanum, they suggested that other populations of Proceratophrys throughout Amazonia are in need of further revision.

During fieldwork along the Teles Pires River in southern Amazonia, we collected specimens of Proceratophrys previously identified as P. concavitympanum (Ávila, Kawashita-Ribeiro & Morais, 2011). Here, we combine morphological, bioacoustical, and mtDNA evidence to elucidate the taxonomic status of this population and describe it as a new species.

Materials & methods

Results

Proceratophrys korekore sp. nov. (Fig. 1–4)

urn:lsid:zoobank.org:pub:4077F2CC-A0B1-49AC-B562-2FE7CC929668

Proceratophrys concavitympanum Ávila, Kawashita-Ribeiro & Morais (2011) (part)

Holotype. ZUFMS-AMP08100, adult male, from Jacareacanga municipality, Pará state, Brazil (09°19′1.00″ S, 56°46′35.76″ W, 200 m a.s.l.; datum = SAD69), collected on 08 November 2016, by L.A. Silva.

Paratypes. ZUFMS-AMP08098, juvenile from the type locality, collected on 30 May 2017, by L.A. Silva and E.A. Pereira; ZUFMS-AMP08099, juvenile from the type locality, collected on 25 May 2017, by L.A. Silva and E.A. Pereira; ZUFMS-AMP08101, ZUFMS-AMP08103, two juveniles, and ZUFMS-AMP08102, adult male, collected along with the holotype by L.A. Silva; ZUFMS-AMP08104, juvenile, from the type locality, collected on 22 May 2016, by L.A. Silva; ZUFMS-AMP08105, adult male, from the type locality, collected 26 February 2017, by L.A. Silva; ZUFMS-AMP08116, adult female, from Paranaíta municipality, Mato Grosso state, Brazil (09°39′47″ S, 56°28′36″ W, 200 m a.s.l.; datum = SAD69), collected on 08 November 2016, by L.A. Silva; ZUFMS-AMP08117, adult female, from Paranaíta municipality, Mato Grosso state, Brazil (09°39′47″ S, 56°28′36″ W, 200 m a.s.l.; datum = SAD69), collected on 24 February 2016, by M.O. Neves; ZUFMS-AMP13680, adult male, from the type locality, collected on 2 May 2018, by L.A. Silva and H. Folly; ZUFMS-AMP13681, adult male, from the type locality, collected on 14 May 2018, by L.A. Silva and H. Folly. CFBH 20675, 20676, 20678, adult males, and CFBH 20677, adult female, from Paranaíta municipality, Mato Grosso state, Brazil (9°39′52.99″ S, 56°28′36.12″ W, 270 m a.s.l.; datum = WGS84), collected on 24 November 2008, collector not informed; ZUEC 14874, 14875, 14950 adult females, and ZUEC 14876, adult male, from Paranaíta municipality, Mato Grosso state, Brazil (9°39′52.99″ S, 56°28′36.12″ W, 270 m a.s.l.; datum = WGS84), collected on 21 February 2009, by L.F. Toledo, N.R. Silva, O. Araújo and I. Prates; ZUEC 16011–16014, 16719, juveniles, and ZUEC 16015, adult female, from Paranaíta municipality, Mato Grosso state, Brazil (9°39′52.99″ S, 56°28′36.12″ W, 270 m a.s.l.; datum = WGS-84), collected on 11 June 2009, by L.F. Toledo, O. Araujo, R.S. Nelson and P.L.M. Fontana; UFMT-A 7534, juvenile from UHE Foz do Apiacás, Paranaíta municipality, Mato Grosso state, Brazil (9°22′58.44″ S, 57°3′47.16″ W, 270 m a.s.l.; datum = WGS84), collected on 01 June 2008, collector not informed; UFMT-A 7963, juvenile, from UHE Foz do Apiacás, Paranaíta municipality, Mato Grosso state, Brazil (9°22′58.44″ S, 57°3′47.16″ W, 270 m a.s.l.; datum = WGS-84), collected on 16 September 2008, collector not informed; UFMT-A 9882, 10038, juveniles, from UHE Foz do Apiacás, Paranaíta municipality, Mato Grosso state, Brazil (9°22′58.44″ S, 57°3′47.16″ W, 270 m a.s.l.; datum = WGS84), collected on 20 April 2009, collector not informed; UFMT-A 9990, adult female, from UHE Foz do Apiacás, Paranaíta municipality, Mato Grosso state, Brazil (9°22′58.44″ S, 57°3′47.16″ W, 270 m a.s.l.; datum = WGS84), collected on 20 September 2009, collector not informed; UFMT-A 10041, 10046, 10054, juveniles, from UHE Foz do Apiacás, Paranaíta municipality, Mato Grosso state, Brazil (9°22′58.44″ S, 57°3′47.16″ W, 270 m a.s.l.; datum = WGS84), collected on 17 April 2009, collector not informed; UFMT-A 10067, juvenile, from UHE Foz do Apiacás, Paranaíta municipality, Mato Grosso state, Brazil (9°22′58.44″ S, 57°3′47.16″ W, 270 m a.s.l.; datum = WGS84), collected on 19 April 2009, collector not informed; UFMT-A 10109, juvenile, from UHE Foz do Apiacás, Paranaíta municipality, Mato Grosso state, Brazil (9°22′58.44″ S, 57°3′47.16″ W, 270 m a.s.l.; datum = WGS84), collected on 22 April 2009, collector not informed.

Diagnosis. The new species can be distinguished by the following combination of traits: (1) medium size (39.8–44.1 mm SVL in adult males; 43.8–57.6 mm SVL in adult females); (2) upper eyelid border with fused and small pointed warts; (3) proportional measurements ED/END 1.1–1.3; (4) presence of a single row of tubercles of different sizes bordered with some sparse tubercles on the forearm; (5) call duration of 0.162–0.332 s; 18–31 pulses/call; pulse rate of 96.4–111.1 pulses/s.

Comparison with other species. Proceratophrys korekore sp. nov. differs from P. appendiculata, P. belzebul, P. boiei, P. gladius, P. itamari, P. izecksohni, P. laticeps, P. mantiqueira, P. melanopogon, P. moehringi, P. paviotii, P. phyllostomus, P. pombali, P. renalis, P. rondonae, P. sanctaritae, P. subguttata, and P. tupinamba by the absence of a single unicuspidate palpebral appendage (a single and long unicuspidate palpebral appendage in all species, except in P. rondonae, which has a single and short multi-cuspidate palpebral appendage). In addition, P. korekore sp. nov. can be distinguished from P. appendiculata, P. belzebul, P. gladius, P. itamari, P. izecksohni, P. laticeps, P. mantiqueira, P. melanopogon, P. moehringi, P. phyllostomus, P. pombali, P. sanctaritae, P. subguttata, and P. tupinamba by lacking a rostral appendage (present in those species). Proceratophrys korekore sp. nov. differs from P. avelinoi, P. bigibbosa, P. brauni, and P. palustris by lacking postocular swellings (present in these species). Proceratophrys korekore sp. nov. has fused small pointed warts on the upper eyelid border (short, fused, and not pointed in P. ararype; small, rounded, and not fused in P. cururu and P. rotundipalpebra; slightly fused without appendage in P. branti, P. huntingtoni, P. vielliardi, and P. moratoi; conical and pointed in P. bagnoi; enlarged, pointed, and with the largest tubercle in the middle more projected than lateral tubercles in P. minuta; small and rounded in P. redacta; multiple short and pointed expansions in P. schirchi). From P. bagnoi, P. concavitympanum, P. dibernardoi, and P. goyana, P. korekore sp. nov. differs by the presence of a single row of tubercles of different sizes bordered with some sparse tubercles on the forearm (two well-delimited rows of tubercles in P. bagnoi, P. concavitympanum, and P. dibernardoi; tubercles not organized in rows in P. goyana). From P. concavitympanum, P. korekore differs by its proportionally larger eyes ED/END 1.1–1.3 (ED/END 0.8–1.0 in P. concavitympanum). From P. salvatori, P. korekore sp. nov. differs by the presence of an ocular-dorsal ridge of warts (lack of ocular-dorsal ridge of warts in P. salvatori).

Proceratophrys korekore sp. nov. also differs from P. ararype by the shorter duration and lower number of pulses/call in the advertisement call (0.162–0.332 s, 18–31 pulses/call versus 0.374–0.648 s, 38–65 pulses/call, respectively). The lower pulse rate differentiates P. korekore sp. nov. (96.4–111.1 pulses/s) from P. moratoi (69–86 pulses/s), and the lower dominant frequency (861.3 Hz) from P. ararype and P. moratoi (1,033.6–1,378.1 Hz and 1,153–1,594 Hz, respectively).

Description of the holotype. Head wider than long, head length 70% of SVL, snout semi-circular in dorsal and ventral views, obtuse and slightly vertical in profile; nares elliptical and prominent, canthal crests marked, prominent, and covered by small tubercles; no preocular crests; eyes directed anterolaterally, eye diameter 38% of head length and 95% of upper eyelid width; eyelid with short warts, with the contact point between the ocular-dorsal ridge of warts and the external eyelid margin tubercles in the posterior third region, eight warts on the left eyelid and six on the right (L 2, 2/5, 5; R 2, 2/5, 3), with one more prominent; presence of one row of tubercles on the eyelid; indistinct tympanum; vomerine teeth in two short rows between and above the choanae; frontoparietal crests well developed; region between frontoparietal crests shallow; interocular ridge of warts organized in a row, markedly curved; ocular-dorsal ridge of warts complete from the eyes to the sacral diapophysis, and discontinued to the coccyx region. Dorsal surface, including flanks, arms and legs, with various warts of different sizes and shapes, a single row of tubercles in different sizes bordered with some sparse tubercles on the forearm; ventral surfaces, except hands and feet and cloacal region, covered by numerous small, rounded, uniform warts. Finger lengths IV > II > I > III (Fig. 2B); interdigital webbing absent; inner metacarpal tubercle large and elliptical; outer metacarpal divided in two parts, both internal and external are elliptical; scarce small, rounded supernumerary tubercles; subarticular tubercles large, rounded, but grooved anteriorly and posteriorly. Thigh length longer than tibia length (THL/TL = 1.1), the sum of thigh and tibia lengths 81% of SVL; toe lengths I > II > V > III > IV; inner metatarsal tubercle long, elliptical, spatulated; outer metatarsal tubercle small, rounded; scarce small, rounded supernumerary tubercles; subarticular tubercles large, nearly rounded, grooved anteriorly and posteriorly.

Measurements of the holotype (mm). SVL 43.4; HL 15.7; HW 22.0; DICS 10.8; IND 3.9; END 4.6; ED 6.0; UEW 6.3; IOD 3.2; THL 18.3; TL 16.7; FL 25.4; FHL 23.2 (Table 1).

Color of the holotype in preservative. Dorsal background color brown. Area delimited by the ocular-dorsal ridge of warts light brown, bordered by four dark brown triangular blotches on each side. Two light brown bands from the eye to the upper lip. From two to three transverse dark-brown bars on the fingers and toes. Ventral surface cream with mottling dark brown, becoming darkish in the gular region (Fig. 1B).

Variation. Color variation is related to the size and shape of blotches, and background color varies from light to dark brown in life (Fig. 3) and in preservative (Fig. 4). Some individuals do not have a complete ocular-dorsal ridge of warts, and it varies within individuals with some more complete than others (Fig. 4). Within the collected type series, females are larger than males. Measurements of the type series are provided in Table 1.

Advertisement call. Based on eight calls from one paratype male (ZUFMS-AMP13680) recorded at the type locality, the advertisement call of P. korekore sp. nov. consists of a single pulsed note (Fig. 5) with duration of 0.162–0.332 s (0.251 ± 0.053 s), emitted sporadically with 18–32 pulses/call (25.0 ± 4.4), at a rate of 96.4–111.1 pulses/s (103.9 ± 5.9 pulses/s), and at a dominant frequency of 861.3 Hz, without variation (Table 2).

Among the described advertisement calls of the closely related species (P. ararype, P. concavitympanum, P. korekore sp. nov., P. moratoi, P. salvatori and P. strussmannae), P. korekore sp. nov. has a shorter call duration than P. ararype (0.374–0.648 s) (Mângia et al., 2018). The pulse rate of P. korekore sp. nov. is greater than P. moratoi (69–103 pulses/s) and P. salvatori (54–61 pulses/s) (Magalhães et al., 2020). Although the dominant frequency did not vary in P. korekore sp. nov., probably due to few calls and a single individual recorded, this parameter is lower than P. ararype (1,034–1,378 Hz), P. moratoi (1,153–1,594 Hz) and P. salvatori (1,572–1,875 Hz) (Mângia et al., 2018; Magalhães et al., 2020). The call parameters of P. korekore sp. nov. are similar to P. concavitympanum (Santana et al., 2010), and we were unable to compare with P. strussmannae because its advertisement call is not described.

Phylogenetic analysis. Our 16S tree confidently placed P. korekore sp. nov. as the sister taxon of P. concavitympanum, within a well-supported clade including P. strussmannae, P. salvatori, P. moratoi, and P. ararype (Fig. 6), hereafter called the P. concavitympanum clade. For some deeper nodes within Proceratophrys, our tree had low posterior probabilities, but this is expected given it is based on a single mtDNA locus utilized for barcoding species. Average sequence divergence between the new species and congeners ranges from 3.0% (P. aff. ararype) to 10.4% (P. redacta) (Table 3; Document S2). Furthermore, the mitochondrial haplotype network (Fig. 7) shows seven distinct mitochondrial lineages and no haplotype sharing between species of the P. concavitympanum clade.

Distribution. The new species is known only from the type locality, Jacareacanga municipality, Pará state, and few sites on the other side of the Teles Pires River, Paranaíta municipality, Mato Grosso state (Fig. 8).

Natural History. Proceratophrys korekore sp. nov. was found inhabiting only dense ombrophilous forest formations on both banks of the Teles Pires River. During nocturnal surveys between 18:00 and 21:00 h in the rainy season (from October to June), we observed males of P. korekore sp. nov. calling from the leaflitter on the banks of temporary streams. Some males were also found calling on bare soil near the edges of waterbodies. Additionally, individuals of the new species were observed during surveys (both diurnal and nocturnal) moving through the forest or captured using pitfall traps, even far from water bodies. Sympatric species include Ameerega munduruku, Ceratophrys cornuta, and Lithodytes lineatus. The main anthropogenic threats to the type locality are illegal logging and the often-subsequent deforestation for cattle grazing. Furthermore, illegal gold mining inside the forests (locally called “garimpo”) was observed during fieldwork. The activity of these illegal miners consists of clearing all vegetation of a target area and then destroying entire sections of stream bank to extract gold using mercury, a heavy metal that pollutes water supplies and poisons fish stocks (Silva et al., 2018). Finally, the Teles Pires River has also been dammed by multiple hydroelectric power plants, which have caused considerable natural habitat losses and fragmentation.

Etymology. The specific epithet “korekore” is a noun in apposition that means frog in the language of the Mundurukus, an indigenous group that inhabits the southwestern parts of Pará state and the northern region of Mato Grosso state, Brazil. We suggest the following Portuguese vernacular names “sapo-korekore” or “sapo-de-chifre-dos- mundurukus”.

Discussion

The genus Proceratophrys has been historically arranged into three morphological groups (Giaretta, Bernarde & Kokubum, 2000; Kwet & Faivovich, 2001; Prado & Pombal, 2008; Amaro, Pavan & Rodrigues, 2009) without phylogenetic support (Amaro, Pavan & Rodrigues, 2009; Mângia et al., 2018). Resolving the phylogenetic relationships within Proceratophrys is essential to understand the genus’ diversity and evolutionary history. In previous studies on Proceratophrys using molecular data, only three clades were consistently recovered as monophyletic: the P. bigibbosa species group distributed in southern South America (Kwet & Faivovich, 2001), the clade formed by P. cristiceps, P. minuta, and P. redacta distributed in northeastern Brazil, and the P. concavitympanum clade composed of P. concavitympanum, P. korekore (Amazonia), P. ararype (Caatinga), P. moratoi, P. salvatori and Proceratophrys aff. ararype (Cerrado) (Amaro, Pavan & Rodrigues, 2009; Pyron & Wiens, 2011; Teixeira et al., 2012; Dias et al., 2013; Mângia et al., 2018; Magalhães et al., 2020; Cruz & Napoli, 2010). However, the relationships among the remaining sequenced (13 species) and not sequenced (15 species) species of Proceratophrys lack phylogenetic resolution and there are no morphological features that could be used to group them, highlighting the need for more robust phylogenetic analysis using multi-locus approaches and coalescent-based methods.

The population from Tocantins state, which we called P. aff. ararype here, has an average 1.8% genetic divergence in 16S from P. ararype. Genetic distance between species in the 16S barcode mtDNA locus is usually low within Proceratophrys, with some morphologically distinct species being less than 1.5% divergent (e.g., P. belzebul-P. appendiculata-P. izecksohni; P. itamari-P. mantiqueira) (Dias et al., 2013, Document S2). Nevertheless, based on the distributions of P. aff. ararype and P. ararype and no shared haplotypes among populations, further investigation is needed to clarify the taxonomic status of the population from Tocantins.

The description here of P. korekore sp. nov. constitutes the third new species described from the area under the influence of the São Manoel and Teles Pires hydroelectric power plants, the others being the watersnake Helicops apiaka (Kawashita-Ribeiro, Ávila & Morais, 2013) and the poison-frog Ameerega munduruku (Neves et al., 2017). These three taxa are known only from this region, which is also located in the ‘arc of deforestation’ (Souza et al., 2019). Habitat loss in Amazonia due to river dams and deforestation are directly causing vertebrate extinctions (Benchimol & Peres, 2015; Silva et al., 2018). This scenario underscores the need for sampling surveys and integrative taxonomic approaches to reveal Neotropical anuran diversity, which will lead to a better understanding of species distributions and evolutionary history.

Appendix i

Supplemental Information