Rhinophis zigzag Gower & Maduwage, 2011, sp. nov.
Creators: name: Gower, David J.
name: Maduwage, Kalana
Publisher: name: Zenodo
Year: 2011
Subjects: Biodiversity
Taxonomy
Animalia
Chordata
Reptilia
Squamata
Uropeltidae
Rhinophis
Rhinophis zigzag

description: Rhinophis zigzag sp. nov.
(Figs. 1, 6 – 8; Table 2; Appendix)
Rhinophis dorsimaculatus Deraniyagala, 1941: Somaweera (2006: 235, photograph A) Rhinophis sp. 2: Cadle et al. (1990)
Holotype. CAS 226306, male, “Bibilegema Rd.”, near Passara, Province of Uva, collected May 1974 by C. Gans. Photographs presented in Figs. 6 – 8. There are no precise coordinates for the locality, though Bibilegama is at 06°54’N, 81°08’ E and approximately 1,000 m altitude.
Paratypes. 13 specimens, all from the type locality: CAS 225690 (Bibilegama, 20 November 1974), 225691 (Bibilegama, 20 November 1974), 225902 & 225903 (Bibilegama, 1050 m, 4 May 1976, C. Gans), 225967, 225968 & 225969 (Bibilegama, 28 July 1976, L. Jayawickrama), 226014, 226015 & 226016 (Bibilegama, lower section, 31 July 1976, L. Jayawickrama), 226307 (Bibilegama, 28 May 1974, C. Gans); WHT 5243 and WHT 5284 (Bibilegama, 2 and 13 November 2000, M. M. Bahir and C. Gans).
Diagnosis. In having more than 200 ventral scales, R. zigzag (207 – 221) differs from all other Rhinophis except R. dorsimaculatus, R. oxyrhynchus, R. punctatus, R. porrectus, R. homolepis, and R. sanguineus. Of these six species, R. punctatus, R. porrectus, and R. dorsimaculatus have more than 230 ventrals whereas R. zigzag has fewer than 230, and the former three species plus R. oxyrhynchus have a dorsally crested/carinate rostral scale vs the dorsally rounded rostral of R. zigzag. Rhinophis homolepis has a notably smaller head and its tail shield lacks the heterogeneity in the size of the spines seen in R. zigzag. Rhinophis sanguineus also lacks notable spine heterogeneity on the tail shield, and differs from R. zigzag also in having a much larger shield, conspicuous (but low) multiple carinae on the distal edges of scales on the underside of the tail, and in having a shorter rostral that barely interjects between the prefrontal scales. Rhinophis zigzag also differs from all congeners in its distinctive and consistent colour pattern of a dark middorsal, meandering/ zigzag stripe.
Description of holotype. Some morphometric and meristic data are given in Table 2. Head small; snout and rostral pointed. Rostral trihedral anteriorly, with clear but rounded ridge dorsally (sharp crest absent), arched in lateral and anterior views. Rostral much longer than wide, maximum width at the level of anterodorsal corner of first supralabials. Rostral several times longer than rostral-frontal gap. Frontal longer than wide, six-sided, anterolateral (ocular) margins shortest and slightly converging posteriorly, posterolateral margins longest. Frontal shorter, wider than rostral. Paired nasals separated by posterior of rostral. Small subcircular external naris slightly countersunk within small depression in anteroventral corner of nasal. Prefrontals wider/taller than long, shorter than frontal, very briefly in midline contact between frontal and rostral. Four supralabials; first smallest; second a little longer, much larger; fourth much the largest. Ocular contacts supralabials 3 and 4; about five times longer than diameter of small, slightly bulging eye (pupil subcircular) in anteroventral corner. Paired parietals shorter and wider than frontal; posterior margins forming a rounded right angle; briefly in midline contact (left overlaps right). Posterior edge of each parietal contacts fourth supralabial plus four temporal-region scales. Infralabials three: first shortest, third a little and second notably larger. Small, slightly prominent mental just contacts first midventral scale. First and second ventrals longer than wide, these proportions subequal in third; fourth and subsequent ventrals wider than long.
Seven teeth in each maxillary row, seven or eight in mandibular rows. Teeth simple, pointed, retrorse, straight. Spacing of teeth even in all rows. Dentary teeth hidden deeper in gingivae and less prominent than maxillary rows. Anteriormost maxillary teeth approximately just behind ventral end of suture between first and second supralabials, posteriormost tooth approximately level with posterior lower margin of third supralabial. Dentary row of similar length and alignment.
Body subcylindrical to slightly dorsoventrally compressed. All head and body scales lack keels, macroscopically smooth. Dorsal body scales generally evenly sized around and along body, except for those involved in dorsal scale row reductions. Midline ventral scales between mental and anal generally evenly sized except for gradually narrowing anterior- and posteriormost members. Ventrals 209, at midbody 1.3 times as broad as exposed part of adjacent, first row of dorsals. Anteriorly 19 dorsal scale rows, reducing to 17 rows by midbody.
4+5 (48) +5 (53) 4+5 (77)
Scale reduction: 19 ---------------------------------------------- 17 ---------------- 19 --------------- 17
3+4 (36), +4 (37), 4+5 (41) +5 (49) 4+5 (72)
Paired anals (right overlaps left) considerably larger than posteriormost ventrals and anterior subcaudals; distal margin of each overlaps three scales in addition to anteriormost subcaudals. Base of tail with 14 scale rows in addition to first pair of subcaudals. Six subcaudals on each side, anteriormost four paired/divided. Tail scales macroscopically smooth though with two to seven macroscopically inconspicuous keels on posterior portion of posteriormost caudals (increasingly prominent posteriorly). Caudal shield conical, forming tip of tail (shield base not as wide as body); oval in posterior view; a little shorter than shielded part of head; surrounded by last (undivided) subcaudal scale and 13 caudal scales (14 total); readily visible from below and especially from above. Shield surface covered by spines except for very narrow, glossy ring around shield base and narrow dorsal midline strip towards and at shield apex; spines distinctly larger (up to 0.4 mm long) in pair of single paramedian rows flanking spineless strip. Spines with laterally compressed tips and broad bases.
In preservative, background body colour yellowish to pale tan/beige. Slightly irregular dorsal longitudinal zigzag pattern along whole body formed by darker (pale brown) patches generally on dorsalmost five or six scale rows. Contrast between paler background and darker patches less marked anteriorly. Some other body scales pale brown, either singly or forming intermittent narrow stripe on fourth dorsal scale row (not anteriorly, strongest at midbody). Ventrals and lowermost dorsals yellowish with occasional pale brown flecks. Anals and last three ventrals yellow/cream without brown marks. Subcaudals brown laterally, yellowish medially (forming irregular midventral yellowish stripe). Five dorsalmost scale rows on tail entirely brown; irregular pale lateral stripes below this across up to 3.5 scale rows each. Caudal shield mostly brown (continuation of dorsal tail colour) with irregular yellow-orange midline stripe towards and at apex. Broad spine bases orange-yellow, laterally-compressed tips orangebrown. Head yellowish, slightly darker than background body colour; low-contrast brown stripe on upper edge of fourth and third supralabial extending across lower edge of ocular (and eye). Brown spot across anterior edge of prefrontal, anterodorsal edge of second supralabial, nasal and posterior of rostral; additional brown blotches on parietals and mid-posterior of frontal. Ventral scales on anterior of body and infralabials and mental unblemished, but small brown flecks present on anteriormost chin shields (and one on right second infralabial).
Variation. See Table 2 for morphometric and meristic data. Scale-row reductions match holotype with minor variation (Appendix). Slight indication of longer heads in males (Table 2), but sample size small; little difference in relative tail length but males only sex to have up to 6 subcaudals. Shape of tail shield in posterior view fairly consistently similar to holotype. Colour pattern generally matches holotype with minor variation. For example: last two (CAS 226014, 225902) or four (CAS 225967) ventrals entirely pale, or with brown flecks (CAS 226015); anals flecked in CAS 225690, 225967; middorsal zigzag broken into patches anteriorly in WHT 5243, CAS 225690 and 225967; contrast between paler and darker regions stronger in some specimens (e.g., WHT 5284); scales between infralabials brown in CAS 225690, 225967 226015; brown spots not clear on prefrontals of CAS 225690; tail shield more orange than brown in CAS 226014, more yellow in WHT 5284.
Colour in life. The dorsal surface of a fresh specimen (misidentified as R. dorsimaculatus) in a photograph presented by Somaweera (2006: 235, photograph A) shows the pale colour (pale tan in preservation) to be a dull yellow and the darker dorsal zigzag (brown in preservation) to be a pale lilac-brown.
Etymology. The species name is an allusion to the distinctive zigzag dorsal stripe, present in all known specimens. The specific epithet is considered a noun in apposition.
Suggested common name. Zigzag Rhinophis (English).
Distribution, natural history and conservation. Rhinophis zigzag is known only from the type locality, Bibilegama, in the Wet Zone of the central hills of Sri Lanka (06°54’N, 81°08’ E, alt. 1,067 m). As far as we are aware, all known specimens were collected from soils in agricultural habitats. Although the exact range of the species is unknown it is unlikely to be large based on its absence in reasonably large collections of uropeltids from across the region (BMNH, CAS, WHT). Given its small probable range and very few known localities (not known to include protected areas), R. zigzag is likely to fall into one of the IUCN’s threatened categories.
Remarks. In basic scale counts, Rhinophis zigzag resembles R. homolepis and R. sanguineus most closely among congeners, but differs clearly from these species in its tail shield (smaller and with heterogeneity in its spines). Rhinophis zigzag also differs clearly from the other Sri Lankan uropeltids that are currently assigned to other genera (Pseudotyphlops, Uropeltis, e.g., McDiarmid et al., 1999), not only in its distinctive colour pattern but also, for example, P. philippinus has a much larger and almost flat tail shield, and U. phillipsi and U. melanogaster have much smaller tail shields that are shorter vs longer than the part of the head anterior to the frontal. Uropeltis ruhunae has keels rather than spines on its tail shield.
Somaweera (2006: 235, photograph A) misidentified a specimen of R. zigzag as R. dorsimaculatus. The latter is a poorly known species (two documented specimens; Deraniyagala, 1941) but is clearly differentiated from R. zigzag by having more than 230 ventral scales (vs 207 – 221), a dorsally carinate (vs rounded) rostral, and black, mostly discontinuous paravertebral blotches vs a more or less continuous, non-black zigzag. Carl Gans recognized that R. zigzag represented an undescribed species (“ Rhinophis sp. 2”, Cadle et al., 1990).
description: Published as part of Gower, David J. & Maduwage, Kalana, 2011, Two new species of Rhinophis Hemprich (Serpentes: Uropeltidae) from Sri Lanka, pp. 51-68 in Zootaxa 2881 on pages 59-65, DOI: 10.5281/zenodo.201615