Rhinophis mendisi GOWER, 2020
Can you confirm these amateur observations of Rhinophis mendisi?
|Higher Taxa||Uropeltidae, Henophidia, Alethinophidia, Serpentes, Squamata (snakes)|
|Common Names||E: Mendis’ rhino- phis or Mendis’ shieldtail|
Sinhala: Mendisge thudulla
Tamil: Mendisin nilakael pambu
|Synonym||Rhinophis mendisi GOWER 2020|
Rhinophis homolepis — OLORI & BELL 2012
Rhinophis trevelyanus — OLORI & BELL 2012: table S1
|Distribution||SW Sri Lanka (near Balangoda)|
Type locality: Rosgalla or Rasagalla or Rosafalla, Ceylon based on specimen labels and MCZ catalogue. Most likely the village of Rasagalla (also spelled Rassagala), near (ca. 8 km to the northwest of) Balangoda, Ratnapura District, Sabaragamuwa Province, Sri Lanka. (6.69° N, 80.64° E; ca. 550 m a.s.l.: data from GoogleEarth). There is an estate by the name of Rasagalla immediately to the West of the village, and the elevational range of this general area is ca. 550–700 m
|Types||Holotype. MCZ 18037 (Fig. 1), adult male, collected by Frank Wall and Rasagalla is the only similar place name on Wall’s (1921) map, on which it lies close to and West of Balangoda. There is no collection date associated with MCZ 18037, but Wall (1868–1950) collected Indian and Sri Lankan snakes while he was in the Indian Medical Service, in which he served from 1894 until retiring to the UK in 1925 (Adler 1989).|
Paratypes (n = 4). MCZ 18034 (Fig. 3 in Gower 2020), 18035 (Fig. 4), 18036, and 18038 (Fig. 5); same collection data as for holotype.
|Diagnosis||Diagnosis (n=14). A Rhinophis restricted to Sri Lanka with 17 dorsal scale rows at midbody, more than 155 and fewer than 180 ventral scales (159–169 in the five types and 161–177 in eight referred specimens), a distinctive colour pattern with more punctate ventral surface and less punctate dorsal surface bearing thin, irregular off-white transverse bars, and a prominent, conical tail shield with small, low, homogenous, ridge-like spines (Gower 2020).|
Identification and comparisons. The new uropeltid species is referred to Rhinophis because it has an eye that lies within an ocular scale (not so in Platyplectrurus Günther, 1868), has a clearly discrete tail shield comprising a single terminal scute, lacks a mental groove (present in Melanophidium Günther, 1864), lacks supraor postoculars or temporals (at least one of which is present in Brachyophidium Wall, 1921, Platyplectrurus, Plectrurus Duméril, 1851, and Teretrurus Beddome, 1886), lacks midline contact between the nasals (present in Brachyophidium, Melanophidium, Platyplectrurus, Plectrurus, Pseudoplectrurus Boulenger, 1890, Teretrurus, almost all Uropeltis [those Uropeltis that lack nasal-nasal contact have small terminal scutes and > 15 dorsal scales rows at, or just behind, midbody]), and it has midbody dorsal scales in 17 rows (15 in Brachyophidium, Melanophidium, Platyplectrurus, Plectrurus, Pseudoplectrurus, Teretrurus).
Rhinophis mendisi sp. nov. differs from all five Indian species of Rhinophis by having a ventral count of > 155 and < 180 (versus more than 200 in R. melanoleucus Cyriac, Narayanan, Sampaio, Umesh & Gower, 2020 and R. goweri Aengals and Ganesh, 2013; fewer than 150 in R. travancoricus Boulenger, 1893; 196 in the only known specimen of R. fergusonianus Boulenger, 1896); and in having 17 midbody dorsal scale rows (versus 15 in R. sanguineus Beddome, 1863) (Cyriac et al. 2020).
Among Sri Lankan congeners, Rhinophis mendisi sp. nov. differs from R. saffragamus (Kelaart, 1853) in having a conical rather than flat tail shield, in lacking midline contact between the opposite nasal shields, in having dorsal scales in 17 rather than 19 rows at midbody, and having > 155 ventrals. The new species differs from R. melanogaster (Gray, 1858), R. phillipsi (Nicholls, 1929), and R. roshanpererai Wickramasinghe, Vidanapathirana, Rajeev & Gower, 2017 in having homogenously sized spines on a simply conical tail shield (versus a less prominent, less conical tail shield with heterogeneously sized spines). The new species differs from R. homolepis (Hemprich, 1820), R. dorsimaculatus Deraniyagala, 1941, R. oxyrynchus (Schneider, 1801), R. porrectus Wall, 1921, R. punctatus Müller, 1832, and R. zigzag Gower & Maduwage, 2011 by having fewer than 178 ventral scales (versus more than 188). Rhinophis mendisi sp. nov. differs from R. lineatus Gower & Maduwage, 2011 in having fewer than 178 ventral scales (versus 180 or more), in having (versus lacking) transverse white bands, and in having a tail shield with a higher aspect ratio. Rhinophis mendisi sp. nov. differs from R. blythii Kelaart 1853, R. drummondhayi Wall, 1921 and R. erangarviraji Wickramasinghe, Vidanapathirana, Wickramasinghe & Ranwella, 2009 in having a terminal scute that is prominent and conical rather than more shield-like with a much lower aspect ratio. Rhinophis mendisi sp. nov. differs from R. philippinus (Cuvier, 1829) in having pale transverse bands on the dorsum. The new species differs from R. tricoloratus Deraniyagala, 1975 in having a punctate colour pattern ventrally, with scales having dark bases and pale margins (versus pale bases and dark margins in R. tricolorata).
Superficially, Rhinophis mendisi sp. nov. resembles the Sri Lankan R. homolepis in terms of the form of its tail shield and its colour pattern, but differs from that species in having many fewer ventrals; the known range of ventrals for the new species is 159–177, and the holotype of R. homolepis (Fig. 7) has 196 (and the types of its subjective junior synonym Mitylia gerrardi Gray, 1858 have 196–203, see below). The focus here is on numbers of ventrals in the types of R. homolepis and its only synonym with extant types (M. gerrardi), because the taxonomy of this taxon is poorly characterised and it is difficult to assign other specimens to this species with certainty (see Discussion). Although subtle, the dorsal longitudinal ridge on the rostral of R. mendisi sp. nov. is also more crest like than in R. homolepis, where it is more gradually rounded, even in larger specimens. Based on observation of preserved specimens, R. mendisi sp. nov. might also have a paler brown dorsal colour versus a darker, more blackish brown in R. homolepis, though observations of R. mendisi sp. nov. in life would be useful to establish whether this difference genuinely serves to distinguish these two species (Gower 2020).
Sexual dimorphism. When the type and referred specimens are considered together, the sample displays a moderately bimodal distribution for the relationship between body and tail length as represented by numbers of ventral and subcaudal scales, respectively (Fig. 8). As far as can be determined, males typically have fewer ventrals and more subcaudals, as also occurs in several other uropeltids (e.g. Jins et al. 2018, Gower 2020).
|Comment||Rhinophis mendisi sp. nov. superficially resembles R. homolepis (Hemprich, 1820) in colour pattern and in its prominent, conical tail shield, but differs from that species in having far fewer ventrals (159–177, n = 13 versus > 195 in the types of R. homolepis and its subjective junior synonym R. gerrardi).|
|Etymology||Named in honour of L.J. Mendis Wickramasinghe, in recognition of his substantial contributions to the discovery, documentation and conservation of Sri Lanka’s herpetofauna. For nomenclatural purposes, the species name is a noun in the genitive case.|
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