Rhinophis melanoleucus, Cyriac & Narayanan & Sampaio & Umesh & Gower, 2020

Cyriac, Vivek Philip, Narayanan, Surya, Sampaio, Filipa L., Umesh, Pavukandy & Gower, David J., 2020, A new species of Rhinophis Hemprich, 1820 (Serpentes: Uropeltidae) from the Wayanad region of peninsular India, Zootaxa 4778 (2), pp. 329-342 : 330-338

Rhinophis melanoleucus sp. nov.

Figs. 1–7 ; Table 1

urn:lsid:zoobank.org:act:1F278995-75D3-4745-8E36-4C29CAEE1256

Holotype ( Figs. 1–3 ). BNHS 3534 , adult female, Wayanad Wild resort, Lakkidi , Wayanad district , Kerala state, India (11.515071° N, 76.036644° E; 825 m elevation: Fig. 4 ). Collected by Surya Narayanan and Pavukandy Umesh, 5 September 2018.

Paratypes (n = 6). BNHS 3535 (male), Kerala Veterinary and Animal Sciences University, Pookode , Wayanad district (11.53336° N, 76.024821° E; 760 m elevation), Vivek Philip Cyriac, 8 October 2011 ; BNHS 3536 (male), Kerala Veterinary and Animal Sciences University, Pookode , Wayanad district (11.53336° N, 76.024821° E; 760 m elevation), Nithin Divakar, Ashok Kumar and Vivek Philip Cyriac, 31 October 2014 ; ZSI / WGRC /IR/ V/3100 (sex not determined), Vythiri road, Pookode, Wayanad district (11.53357°3 N, 76.025864° E; 760 m), Nithin Divakar and Vivek Philip Cyriac, 2 September 2014 ; ZSI / WGRC /IR/ V/3101 (female), Kerala Veterinary and Animal Sciences University, Pookode , Wayanad district (11.53336° N, 76.024821° E; 760 m elevation), Gnana Kumar, Nithin Divakar and Vivek Philip Cyriac, 14 June 2015 ; BNHS 3537 (male: Figs. 5–6 ), Lakkidi (11.514941° N, 76.033989° E; 815 m), Surya Narayanan, 26 April 2017 ; BNHS 3538 (female: Figs. 5–6 ), Lakkidi (11.513941° N, 76.037782° E; 850 m), Surya Narayanan, 12 June 2017 .

Referred specimens (n = 1). BNHS 3539 (sex unknown), Lakkidi (same locality and coordinates as holotype), Surya Narayanan, 11 November 2017. This is a referred rather than type specimen because the posterior part of the body and tail are missing.

Diagnosis. Rhinophis melanoleucus sp. nov. differs from all other species of Rhinophis except R. sanguineus and R. fergusonianus in having 15 dorsal scale rows at (or just behind) midbody (versus 17 or 19 in other congeners). Rhinophis melanoleucus sp. nov. differs from R. fergusonianus in having> 215 ventrals (known range 218–236) versus 195 in the only known specimen of R. fergusonianus . Rhinophis melanoleucus sp. nov. differs from R. sanguineus in having more ventral scales (218–236 versus 181–214 in specimens examined here – see Discussion for comment on Wall’s 1919 report of ventral counts in R. sanguineus of up to 218), in having dark blotches (versus spots) on the ventral surface, and in having a proportionately longer rostral shield: 40.8–42.9% (n = 7; mean 42.0%) versus 32–39.3% (n = 17; mean 36.9%) of head length (= distance between snout tip and posterior edge of fourth supralabial). Only a single nomen is currently considered a synonym of any Indian Rhinophis species— R. microlepis Beddome, 1863 is a subjective junior synonym of R. sanguineus (e.g. Beddome 1886, Smith 1943, Gans 1966, McDiarmid et al. 1999, Pyron et al. 2016). The holotype of R. microlepis differs from the type series of the new species in having a mottled or speckled rather than blotched venter, in having fewer than 218 ventrals (214), and in having a shorter rostral shield (35.8% of head length versus 41% or more).

Identification. The new uropeltid species is referred to Rhinophis because it has an eye that lies within an ocular scale (eye distinct from adjacent scales in Platyplectrurus ), has a clearly discrete tail ‘shield’ comprising a single, enlarged terminal scute (absent in Melanophidium , Brachyophidium , Platyplectrurus , Plectrurus and Teretrurus ), lacks a mental groove (present in Melanophidium ), lacks supra- or postoculars or temporals (at least one of which is present in Brachyophidium , Platyplectrurus , Plectrurus and Teretrurus ), and lacks midline contact between the nasals (present in Brachyophidium , Melanophidium , Platyplectrurus , Plectrurus , Pseudoplectrurus Boulenger, 1890 , Teretrurus , and almost all Uropeltis [those Uropeltis that lack nasal-nasal contact have small terminal scutes and> 15 dorsal scales rows at, or just behind, midbody]).

Description of holotype ( Figs. 1–3 ). See Table 1 for morphometric and meristic data. Good condition; midventral incision (for removal of tissue biopsy) 17 mm extending back from 125 mm from snout tip. Head small, snout pointed. Rostral pointed, longer than wide, without dorsal crest but with narrow, rounded dorsal ridge; in lateral view with slightly convex ventral and (more strongly) dorsal margins; widest at level of anterior upper corner of first supralabials. Rostral many (>12) times longer (in dorsal view) than rostral-frontal gap. Frontal irregularly hexagonal, longer than wide, lateral (ocular) margins slightly converging posteriorly; lateral (ocular) margin shortest, posterolateral edges longest. Frontal much shorter, wider than rostral. Nasals separated from each other by posterior half of rostral. External naris small, subcircular, slightly countersunk within small depression, located at anteroventral corner of nasal. Nasal contacts supralabials 1 and 2. Prefrontals only briefly in contact with each other along midline (left overlapping right), separating frontal from rostral [rostral post-nasal longer than prefrontal midline contact]. Prefrontals wider than long, shorter than frontal. Supralabials four; first smallest, making the least contribution to margin of mouth; fourth largest. Ocular contacts supralabials 3 and 4. Eye distinct, diameter approximately 0.2 times length of ocular, located near anteroventral corner of ocular (closer to lower than anterior edge), only very slightly (at most) bulging slightly from ocular surface, pupil subcircular. Paired parietals longer than wide, approximately as long as but much wider than frontal, posteriorly broadly rounded, angle between posteromedial and posterolateral edges approximately 90°. Parietals in brief midline contact (longer than midline contact between prefrontals), left overlapping right. Each parietal contacts four scales other than head shields. No mental groove; mental pentagonal, slightly wider than long, smaller than infralabials, contacting first infralabials but not first ventral; three pairs of infralabials, second largest, first smallest. First and second ventrals longer than wide, third approximately as long as wide, fourth and subsequent ventrals wider than long. Four (fourth slightly smaller than first three) maxillary and five (fourth and fifth slightly smaller than first three) mandibular teeth on each side. Teeth simple, pointed, distinctly retrorse, straight, evenly spaced.

Body cylindrical. Head and body scales macroscopically smooth. Body scales generally evenly sized on dorsum and along body except for those involved in dorsal scale row reductions. Midline ventral scales between mental and anal of even size, though anteriormost ones gradually narrow. At midbody, exposed part of ventrals approximately 1.4 times wider than scales in first dorsal row. Ventrals 231. Dorsal scale rows 19 anteriorly, reducing to 17 by level with 41st ventral and to 15 rows by 125th ventral, maintained thereafter until close to the vent; Scale row reduction formula:

4 + 5 (41) 4 + 5 (120) +4 (122) -4 (125)

19 --------------- 17 ----------------------------------------- 15

4 + 5 (38) 4+5 (113)

Dorsal scale rows (i.e., excluding subcaudals) 15 at level of first subcaudals. Paired anal scales (right overlying left) considerably larger than posteriormost ventrals and subcaudals. Distal margin of each anal overlaps four (left) and three (right) small scales in addition to anteriormost subcaudals. Six subcaudals on each side, the posteriormost undivided. Some scales at posterior end of specimen bear low, short parallel ridges, towards posterior edges—on last few ventrals, small scales overlapped by anals, lower two or three dorsal scale rows of posterior of body and of tail, and on subcaudals. Last ventrals and subcaudals each bear three or four ridges, last undivided subcaudal bears seven. Tail ‘shield’ large, forming tip of tail, visible from below and especially clearly from above, flattened to slightly concave on anterior end of upper surface, domed posteriorly, longer than wide in dorsal view, wider than depth of tail (at base of shield), larger than head (longer than distance between snout tip and back of fourth supralabial), base surrounded by 15 scales (including last subcaudal). Shield surface roughened, bearing narrow, discontinuous ridges (longer, more continuous stretches located laterally towards shield base), receding and somewhat converging towards tip; evenly spaced, subparallel, approximately straight; low projections but no ridges at (just dorsal to) shield apex.

Colour in alcohol ( Figs. 1–2 ). Rostrum pale orange brown at tip, becoming greyish black posteriorly on the dorsal surface. Head shields greyish black. Supralabial scales greyish black with pale whitish yellow markings, especially towards posterior and/or lower margins. Dorsal body colour uniformly blackish. Ventral surface blackish overall, more greyish on anterior quarter of body. Lateral sides each with approximately 56 obvious, irregular yellowish-white blotches occupying three to five ventralmost dorsal scale rows, many of these blotches taper irregularly dorsally. Ventral scales mostly greyish black, a small number of ventrals with yellowish white marks, typically only on left or right. Subcaudals black. Tail shield black with elongate pale yellowish orange patches on each lateral side, continuous with pale (more whitish, less or not yellowish) markings on ventrolateral surface of tail.

Colour in life ( Fig. 3 ). Dorsal surface uniformly glossy blackish and somewhat iridescent. Lateral and ventral pale blotches on body whitish, more purely so on mid and posterior of body than anteriorly (where whitish scales appear translucent so that darker spots beneath scales slightly visible). Head scales blackish except for paler, orangebrownish rostral and whitish lower and/or posterior parts of supralabials. Ventral surface of tail blackish except for whitish ventrolateral markings. Pale elongate markings on tail shield pale orange, paler and more whitish anteriorly than posteriorly.

Paratypes. All paratypes in good condition, BNHS 3535 and BNHS 3536 a little dehydrated with convoluted spines, the latter specimen’s head slightly crushed. Meristic and morphometric data are provided in Table 1. The number, arrangement and overlapping of head shields are similar to the holotype with the following exceptions. In BNHS 3537 and BNHS 3538 ( Fig. 6 ) the parietals are each wider than long, slightly shorter than the frontal, and with somewhat scalloped rather than broadly rounded posterior margins. The prefrontals in ZSI/WGRC/IR/V/3100, BNHS 3537 and BNHS 3538 make more substantial midline contact than in the holotype, so that the length of rostral behind the nasals is shorter than the rostral-frontal distance. Tooth counts same as in holotype, where examined

(BNHS 3535, BNHS 3536, ZSI/WGRC/IR/V/3100). Rostral length from approximately 5 (ZSI/WGRC/IR/V/3100) to 14 (ZSI/WGRC/IR/V/3101) times distance between rostral and frontal. Eye diameter approximately 0.2–0.25 times length of ocular shield.

Ventrals 218–236, subcaudals 6–8. Minor variation in how many of the anteriormost ventrals are longer than wide, for example only the first ventral in BNHS 3538. Dorsal scale rows in all specimens reduce from 17 to 15 by between the 100 th (ZSI/WGRC/IR/V/3100) to 139 th (BNHS 3537) ventral (see Appendix 2), by or just behind midbody. Dorsal scale rows at the anterior of the tail 12–15; scales around base of tail ‘shield’ 13–15 including last subcaudal(s). Terminal subcaudal in all types undivided. ZSI/WGRC/IR/V/3101 resembles holotype in having all other subcaudals paired (divided), while in other paratypes paired and unpaired subcaudals are mixed along length of tail. Anal shields each overlap three small scales on each side in all paratypes. Scales on the underside of the pos- terior region of the body and the tail bear short parallel ridges that are variable in their exact distribution (e.g. only on last subcaudal in ZSI/WGRC/IR/V/3101; on last ventrals, anals and subcaudals in BNHS 3536), number (3–9 per scale) and prominence, least prominent in BNHS 3538, ZSI/WGRC/IR/V/3101 and ZSI/WGRC/IR/V/3100. Colour pattern similar to holotype except that the lateral and ventral blotches are pale pinkish in smaller individuals. Number of lateral pale blotches 55 (BNHS 3535), 52 (BNHS 3538), 47 (ZSI/WGRC/IR/V/3101; BNHS 3537), 46 (BNHS 3536), 44 (ZSI/WGRC/IR/V/3100), with lower numbers typically occurring in specimens in which anteriormost blotches are greatly elongate, extending 20–25 scales back from posteriormost surpalabial.

Everted hemipenes of BNHS 3537 ( Fig. 6 ) short (ca. 2.5 mm), stout (ca. 1.0 mm wide at base). Interpreted as unilobed but with substantial medial lobe-like process (lacking any sign of sulcus spermaticus) ca. 1.0 mm from tip of organ. Medial process shorter and more slender than lobe, with irregular longitudinal folds. Lobe subcylindrical, ornamented densely with small spines throughout; shallow sulcus spermaticus terminating at base of lobe with large flap and several globular folds.

Sexual dimorphism. There is no clear evidence of sexual dimorphism in number of ventral scales in the types, with the three females having 225–235 and three males having 218–236 (Table 1). Males tend to have proportionately slightly longer tails (2.6–3.5 % of total length) than females (2.3–2.8 %) and have more subcaudals (7,7 or 8,8) than females (6,6 or 6,7). Both females and males have ridges on scales on the underside of the tail and posteriormost part of the body, but these are more prominent in males.

TABLE 1. Meristic and metric data for holotype (*) and paratypes of Rhinophis melanoleucus sp. nov., the holotype of R. fergusonianus , and the lectotype of R. sanguineus . Measures given in mm. SL4 = fourth supralabial; DSR1 = first dorsal scale row; hyphen (-) indicates shortest distance between two points.

Etymology. From the Ancient Greek mélas (black) and leukós (white), in reference to the unusual (for uropeltids) black and white colouration. For nomenclatural purposes, the species name melanoleucus is a noun in the genitive case.

Distribution, habitat, natural history and conservation status. Rhinophis melanoleucus sp. nov. is known only from the vicinity of Lakkidi in the Wayanad District of Kerala state, at approximately 750–850 m elevation in the evergreen hills of the Western Ghats. The habitat in the vicinity of the type locality is shown in Fig. 7 . We suspect that the new species has a larger distribution, at least in the Wayanad region, but it is not widespread and/or frequently encountered enough to have been previously collected or reported. The new species is likely to qualify for Data Deficient status under IUCN Red List criteria, at least until new field surveys are undertaken and/or additional specimens from other localities can be found in other collections.

The holotype was found at 08:00, moving on the surface of a forest track alongside a stream and close to an adjacent tea plantation. Paratypes BNHS 3537 and BNHS 3538 were found at 15:00 and 09:00, respectively, the former dead on a paved road, and the latter on the ground surface in an abandoned coffee plantation. Referred specimen BNHS 3539 was dug from a depth of approximately 0.5 m during excavations for a road extension in mid-elevation wet-evergreen forest (rainfall approximately 5,000 mm per year) with trees including Cinnamomum malabatrum (Burm. f.) J.Presl, Meliosma simplicifolia (Roxb.) , Actinodaphne malabarica Balakr. and Elaeocarpus tuberculatus Roxb. in addition to farmed coffee. Paratypes ZSI/WGRC/IR/V/3100 and ZSI/WGRC/IR/V/3101 were found at approximately 07.00 and 18.30 respectively, moving among grass on the side of a tarred road inside the Veterinary and Animal Sciences University campus, Pookode. Paratypes BNHS 3535 and BNHS 3536 were found dead on a tarred road between 07.00 and 08.00.

In a few days of temporary captivity, BNHS 3538 refused to feed on live earthworms provided. When handled, none of the individuals in the type series attempted to bite. They showed an inclination to burrow in soil and in the hand. At the localities reported here, Rhinophis melanoleucus sp. nov. occurs broadly sympatrically (within a radius of ca. 15 km) with other uropeltids including at least R. sanguineus , Uropeltis cf. nilgherriensis, Teretrurus hewstoni , Melanophidium bilineatum and M. wynaudense .

Figures

FIGURE 1. Dorsal and ventral view of the holotype (BNHS 3534) of Rhinophis melanoleucus sp. nov. Scale bar 25 mm. Photographs by VPC.

FIGURE 2. Views of the head (left) and tail (right) of the holotype (BNHS 3534) of Rhinophis melanoleucus sp. nov., shown in dorsal (upper), lateral (middle) and ventral (lower) views. Not to same scale; see Table 1 for size of specimen. Photographs by VPC.

FIGURE 3. Holotype (BNHS 3534: total preserved length 461 mm) of Rhinophis melanoleucus sp. nov. in life. Photograph by SN.

FIGURE 4. Map of southwestern peninsular India showing location of type localities of Indian species of Rhinophis. The precise type locality of R. fergusonianus is not known, so an approximate position for “Cardamom Hills” is shown.

FIGURE 5. Two (of six) paratypes of Rhinophis melanoleucus sp. nov. Upper row BNHS 3537, lower row BNHS 3538; left column dorsal view, right column ventral view. Not to same scale; total length of BNHS 3537 303 mm, of BNHS 3538 357 mm. Photographs by SN.

FIGURE 6. Heads and tails of two (of six) paratypes of Rhinophis melanoleucus sp. nov. Two left columns are BNHS 3537, two right columns BNHS 3538. Shown in dorsal (upper row), ventral (middle row) and lateral (lower row) views. Lateral views are of right (head) and left (tail) sides. Scale bars 10 mm. Photographs by SN.

FIGURE 7. Habitat in the vicinity of Lakkidi, Wayanad district, Kerala, India, the type locality of Rhinophis melanoleucus sp. nov. Left photograph shows general habitat of upland moist forest and grassland, right photograph shows floor of forest where R. melanoleucus have been found. Photographs by SN.