Rhinophis siruvaniensis, Cyriac & Umesh & Achyuthan & Kulkarni & Ganesh, 2025

Cyriac, Vivek Philip, Umesh, P. K., Achyuthan, N. S., Kulkarni, Vidisha & Ganesh, S. R., 2025, A new species of Rhinophis Hemprich, 1820 (Squamata, Uropeltidae) from Siruvani Hills, Western Ghats, India, Evolutionary Systematics 9 (2), pp. 191-201 : 191-201

Rhinophis siruvaniensis sp. nov.

Table 1 , Figs 2 , 3 , 4

Type material.

Holotype: India • adult; India, Kerala, Palakkad District, Attappadi, Jellipara ; 11.056783°N, 76.607611°E; 781 m a. s. l; 10 July 2015; by Vivek Philip Cyriac, Umesh P. K. & Basil P. Das leg.; BNHS 3387 .

Paratypes: India • 2 adults; India, Tamil Nadu, Coimbatore District, Siruvani Hills, enroute to Sholayur, near Kolikuddam village ; 11.043298°N, 76.691499°E; 1000 m a. s. l.; May 2020; N. S. Achyuthan, Nitin Xavier- leg.; VPRS 0622157 , BNHS 3388 .

Other material.

India • 1 juvenile; slightly dehydrated specimen; same data as holotype; VPRS 0720116 .

Diagnosis.

A species of Rhinophis , characterized by the following combination of characters: 19 dorsal scale rows in the anterior region, 17 at mid-body and 15 near the vent; ventrals 202–205; subcaudals 4–8 pairs; large, dome-shaped tail shield covering the width of the tail; dorsum dark brownish black, lustrous; venter creamy white, this pattern projecting ventrolaterally as intermittent patches; venter and ventrolateral region with large, bold, brownish black blotches occupying 2–5 ventral scales, interspersed with creamy white colour.

Comparisons with congeners. Rhinophis siruvaniensis sp. nov. can be distinguished from all other Peninsular Indian Rhinophis except R. travancoricus and R. goweri by the presence of 17 dorsal scale rows at mid-body (versus 15 mid-body dorsal scale rows in R. sanguineus , R. fergusonianus , R. melanoleucus and R. karinthandani ). It differs from the former two species in having more ventral scales; 202–205 versus <160 in R. travancoricus and <201 in R. goweri . The new species also has more ventrals than R. fergusonianus (> 201 versus 183–197). Rhinophis siruvaniensis sp. nov. differs from R. goweri , R. karinthandani and R. sanguineus in its ventral colouration in having a creamy white venter extending ventrolaterally as intermittent patches along with dark brownish black blotches (versus bright yellow venter heavily speckled with brown in R. goweri ; ventral region off white and heavily speckled with black markings along with an off-white ventrolateral line in R. karinthandani ; and a bright red venter in R. sanguineus ). Rhinophis siruvaniensis sp. nov. closely resembles its sister species R. melanoleucus in overall colouration, but can be easily differentiated by having fewer ventral scales (<206 versus> 217) and in having 17 dorsal scale rows at mid-body (and slightly beyond) (versus 15 dorsal scales at mid-body in R. melanoleucus ).

In addition to biogeographic and molecular phylogenetic distinctiveness, the new species can be distinguished morphologically from all 20 currently recognized Sri Lankan congeneric species as follows: Rhinophis siruvaniensis sp. nov. differs from R. saffragamus (Kelaart, 1853) in having a domed tail shield, lacking midline contact between the nasals, and having 17 mid-body dorsal scale rows (versus a flat, disc-like tail shield; midline contact between nasals; and 19 mid-body dorsal scale rows).

The new species can also be differentiated by its higher ventral count (202–205) from R. blythii Kelaart, 1853 (148–168 ventrals), R. drummondhayi Wall, 1921 (173–191), R. erangaviraji Wickramasinghe, Vidanapathirana, Wickramasinghe & Ranwella, 2009 (142–154), R. gunasekarai Wickramasinghe, Vidanapathirana, Wickramasinghe & Gower, 2020 (177–182); R. lineatus Gower & Maduwage, 2011 (183–195), R. martin Gower, Sampaio, Vidanapathirana & Wickramasinghe, 2024 (167–186), R. melanogaster (Gray, 1858) (152–166), R. mendisi Gower, 2020 (159–177), R. philippinus (Cuvier, 1829) (154–179), R. roshanpererai Wickramasinghe, Vidanapathirana, Rajeev & Gower, 2017 (168–169), and R. tricoloratus Deraniyagala, 1975 ) (163). Rhinophis siruvaniensis sp. nov. has fewer ventrals (<210) than R. dorsimaculatus Deraniyagala, 1941 (227–250 ventrals), R. oxyrhynchus (Schneider, 1801) (211–227), R. porrectus Wall, 1921 (281) and R. punctatus Müller, 1832 (236–246).

The new species differs additionally from R. blythii , R. gunasekarai , R. lineatus , R. martin , R. melanogaster , R. mendisi , R. phillipsi (Nicholls, 1929) , R. roshanpererai and R. zigzag Gower & Maduwage, 2011 in having a large domed tail shield that is almost as wide as the tail (versus a smaller, conical or dome-shaped tail shield notably narrower than the tail).

Rhinophis siruvaniensis sp. nov. shares a broadly overlapping ventral count and a large domed tail shield with R. homolepis Hemprich, 1820 and R. dinarzardae Gower, Sampaio, Vidanapathirana & Wickramasinghe, 2024 , but can be readily differentiated from these two species by its brownish-black dorsum, creamy white venter with black blotches and the lack of a pale white ring around the tail (versus a pale white ring around the base of the tail in R. homolepis and a uniform brown-grey dorsum and punctate venter in R. dinarzardae ).

Description of holotype.

Adult specimen, well-preserved, with a ventral incision for extracting tissue sample. Head small (HL 2.4 % of SVL) with a pointed snout. Rostral pointed, having a narrow, rounded dorsal ridge but no dorsal crest; much longer than wide; and approximately 6.8 times longer (in dorsal view) than rostral-frontal gap. Rostral contacts the nasals and prefrontals, but does not contact the mental when the mouth is closed. Nasals not in contact, separated by the posterior half of the rostral, pierced by the small, subcircular, slightly sunken external naris at the anteroventral corner. Nasals in contact with the rostral, and the first and second supralabials ventrally. Prefrontals wider than long, in contact with each other along the midline but slightly separated anteriorly by the rostral and in contact with the 2 nd and 3 rd supralabials. Prefrontals shorter than the frontal, being slightly longer than half the frontal length. Frontal subhexagonal, longer than wide, but shorter than the rostral; anterolateral margins truncated, lateral (ocular) margins shortest, slightly converging towards each other posteriorly; posterolateral edges longest, meeting each other approximately at a right angle. Frontal in broad contact with parietals, less so with ocular shields, subequal to parietal length. Paired parietals, longer than broad, sub-hexagonal; in narrow contact with each other (IPS 22.7 % of PL), slightly longer than prefrontal length, and separated more by frontal than remaining median interparietal contact. Eye distinct, small, bulging only slightly from ocular surface, its diameter approximately 29.4 % the length of the ocular, located near anteroventral corner of ocular. Four supralabials on each side; the first smallest, rhomboidal, contacting rostral, nasal and 2 nd supralabial; the 2 nd supralabial taller than first and as tall as third; 3 rd supralabial longer than tall; 4 th supralabial largest, larger than parietals and much taller than the rest. The 3 rd and 4 th supralabials occupy more than half the head length and contact the ocular scale. Mental small, sub-pentagonal, much broader than long, smaller than infralabials, and separated from the ventrals and the postmentals by the first pair of infralabials. Three rectangular infralabials on each side; much longer than tall; 2 nd infralabial largest, twice as long as the first; 3 rd infralabial larger than the first and tapering posteriorly.

Body elongated and cylindrical. Dorsal body scales macroscopically smooth, sub-hexagonal, mostly evenly sized. Ventrals 205, much wider than long and evenly sized except for the anteriormost 8 scales which are narrower. Dorsal scale rows 19 anteriorly, reducing to 17 by the 44 th ventral and to 15 rows by 146 th ventral until close to the vent. Dorsal scale row reduction formula:

19 3 + 4 ( 51) 4 + 5 ( 44) 17 3 + 4 ( 146) - 4 ( 142) 15

Anal scales paired, right overlapping the left, much larger than posteriormost ventrals and subcaudals. Subcaudals paired, eight on each side, smooth and longer than adjoining outer rows of scales. Some scales adjoining the subcaudals bear low, short parallel ridges or keels towards posterior edges. Tip of the tail forming a large caudal disc or ‘ shield’ covering ca. 80 % of the tail length; upper surface slightly concave anteriorly, domed posteriorly, longer than wide (TDW 80.7 % of TDL), about 1.3 times wider than the tail depth (at base of shield) and longer than head length. Base of the tail shield surrounded by 15 scales (including the last subcaudals). Tail shield rugose, with several narrow, evenly spaced, broken ridges, somewhat tapering towards the tip.

Colouration in life.

Dorsum dark brownish black, lustrous; venter creamy white, intermittently projecting ventrolaterally as irregular patches; this pattern is interrupted by a consecutive series of large, bold, brownish black blotches stretching 2–5 ventral scales and covering 3–5 adjacent dorsal scales. Subcaudals medially brownish black, flanked on both sides laterally with orange that extends into the tail shield. Tail disc medially brownish black with a creamy orange patch on the lateral side.

Colouration in preservation.

After 2 years in ethanol, overall resembling that in life, except for ventral yellow and subcaudal orange fading to dirty white; iris ashy grey.

Variation

(n = 3). Variation across different meristic and morphometric characters are reported in Table 1 . The paratypes and the referred specimens largely agree with the holotype in overall morphology and colouration except for the frontal length being subequal to frontal width, and parietal length being subequal to parietal width in BNHS 3388 and VPRS 0622157 . Additionally, in paratype BNHS 3388 , the nasals are wider than long. Dorsal scale rows reduce from 19 to 17 by the 50 th ventral and to 15 rows by the 172 nd ventral in VPRS 0622157 , and from 19 to 17 by the 35 th ventral and to 15 rows by the 131 st ventral in BNHS 3388 . The number of scales surrounding the tail shield (including the distal subcaudals) range from 14–17. The ventral scales range from 202–205 and subcaudals range from 4–8 with paratype BNHS 3388 having four and five subcaudals on the right and left side respectively. The referred specimen VPRS 0720116 , which is presumably a neonate, had eight subcaudals on each side but with the 2 nd, 7 th and 8 th subcaudals being undivided.

Etymology.

Toponym, latinised after its known distribution range – the Siruvani Hills.

Distribution and natural history.

Rhinophis siruvaniensis sp. nov. is currently known only from around the type locality. There is a need for further surveys in Attappadi and the wetter regions of the adjacent Anaikatti Hills to more comprehensively document the distribution range of R. siruvaniensis sp. nov. The region is characterized by mid-elevation ( 800–1100 m asl) wet evergreen forests found amidst villages and spice plantations. The type specimens were discovered within cardamom and coffee plantations. Live specimens were typically found under fallen logs and rocks or during minor digging operations inside plantations at a depth of about 30 cm. Local farmers also reported that these snakes are sometimes inadvertently wounded or killed while digging during their usual course of routine work. Roadkills as well as live snake crossings were also sighted in the tarred road connecting Anaikatti and Attappadi that traverses the hills where the type locality lies.

Most of the observed specimens presumably represent adults, except for VPRS 0720116 , which was considerably smaller ( 110 mm total length). This smaller specimen was excavated from the soil in a small plantation at Jellipara, Attappadi, in July 2020. Wall (1919) noted umbilical scars in several small specimens of R. sanguineus found between July and August, and reported that juveniles typically range from 120 to 140 mm in total length. The specimen referred to as VPRS 0720116 was smaller than the juvenile size range indicated by Wall (1919), suggesting that it is a neonate or juvenile. The presence of juveniles in July suggests that the breeding season is likely associated with the southwest monsoons (June – July). Based on anecdotal details from experienced local farmers, R. siruvaniensis sp. nov. is presumed to be active on land surface during night or day and feed on earthworms and are generally observed during June – December, coinciding with the southwest and the northeast monsoons. Other potentially sympatric uropeltids recorded around the type locality include Uropeltis cf. brevis , U. cf. nilgherriensis , U. ocellata (Beddome, 1863) and another recently described species, Teretrurus siruvaniensis Cyriac, Ganesh, Madani, Ghosh, Kulkarni & Shanker, 2024 (see Cyraic et al. 2024).

Figures

Figure 2. Dorsal and ventral views of the holotype (BNHS 3387) of Rhinophis siruvaniensis sp. nov. Photographs by VPC.

Figure 3. Head (left) and tail (right) of the holotype (BNHS 3387) of Rhinophis siruvaniensis sp. nov., shown in dorsal (A, D), ventral (B, E) and lateral (C, F) views. Images are not to scale. Photographs by VPC.

Figure 4. Rhinophis siruvaniensis sp. nov. in life. Paratype VPRS 0622157 showing adult colouration (A) (Photograph by Nitin Xavier) and referred specimen VPRS 0720116 showing juvenile colouration (B) (Photograph by UPK).