Oligodon russelius (DAUDIN, 1803)
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Oligodon russelius
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| Higher Taxa | Colubridae, Colubrinae, Colubroidea, Caenophidia, Alethinophidia, Serpentes, Squamata (snakes) |
| Subspecies | |
| Common Names | |
| Synonym | Coluber russelius DAUDIN 1803 (fide SMITH 1943) Coronella Russelii — SCHLEGEL 1837: 79 (fide DUMÉRIL et al. 1854) Simotes Russelii— DUMÉRIL, BIBRON & DUMÉRIL 1854: 628 Simotes Russelii — JAN 1865 Simotes arnensis — BOULENGER 1890 (partim) Oligodon arnensis — WALL 1921 (partim) Oligodon arnensis — SMITH 1943 (partim) Oligodon russelius — BANDARA et al. 2022: 62 |
| Distribution | Nepal, N India, NE Pakistan Type locality: Vizagapatam (now Visakhapatnam; 17°41’12.54’’N, 83°13’06.53’’E, datum = WGS84; 169 m a.s.l.), Andhra Pradesh, India. |
| Reproduction | oviparous |
| Types | Lectotype: iconotype: Plate 35 in Russell (1796), reproduced in Bandara et al. 2022: 56 (Fig. 3B), designated by Bandara et al. 2022. A juvenile specimen of 171.4 mm SVL (probably a female due to high ventral count, 188 [fide Russell 1796:41]). |
| Diagnosis | Diagnosis. Oligodon russelius comb. nov. is distributed in central, east and northern India, and is distinguished from other congeners by having the following combination of characters: adults reach maximum SVL 650 mm, a single preocular, two postoculars, a single loreal, divided cloacal plate, completely divided nasal, ventrals 169–180 in males and 183–207 in females, subcaudals 46–54 in both males and females combined, temporals 1 þ 2, seven supralabials with third and fourth in contact with eye, DSRs 17-17-15, TL 17.0–18.9% of total length in males, olive brownish dorsum with 30–45 more or less equal in size, pale-edged black cross stripes (with thickness of 1–2 vertebral scales and 4–6 scales in between cross stripes at midbody position) along the body and 6–10 on the tail, two V-shaped black markings on interorbital and parietal–frontal regions, another inverted Y-shaped black marking on the nape. Oligodon russelius comb. nov. is most similar to O. arnensis and the new species, but differs by having several diagnostic characters—see Table 1. Oligodon russelius comb. nov. is also similar to O. churahensis, but differs by having 30–45 (vs. 48–56) cross stripes with 4–6 (vs. 2–4) vertebral scales in-between cross stripes at midbody position along the body and 6–10 (vs. 10– 12) on the tail, inverted Y-shaped black marking (vs. elongated heart symbol) on the nape. (Bandara et al. 2022: 62) Redescription. Based on examined materials (Appendix, n 1⁄4 11). Adults with SVL 318–468 mm, TL 59.5–98.7 mm; head elongate (HL 3.1–4.7% of SVL), wide (HW 58.2– 71.4% of HL), slightly flattened, indistinct from neck; snout elongate (ES 27.2–34.3% of HL), moderate, flat in dorsal view, rounded in lateral profile, rather depressed. Rostral shield large, flat, distinctly visible from above, pointed posteriorly; interorbital width broad (IO 49.3–60.2% of HW); internasals subtriangular; nostrils rather large, nasals large and elongated, divided by the nostril, in anterior contact with rostral, internasal and prefrontal dorsally, first and second supralabial ventrally, loreal posteriorly; loreal single, elongate horizontally; prefrontal rather large, broader than long, and subhexagonal; frontal large, pentagonal, elongate, shortened posteriorly and longer than wide; supraoculars narrow, short, subrectangular, posteriorly wider; parietals large, short, butterfly-wing-like in shape, bordered by supraoculars, frontal, upper postocular anteriorly, anterior and upper posterior temporals, and three or four nuchal scales posteriorly; one preocular, vertically elongated, pentagonal, in contact with prefrontal and loreal anteriorly, supraocular dorsally, and third supralabial ventrally; eye moderate (ED 12.2–18.9% of HL), round, nearly half of the size of snout length (ED 38.5–58.0% of ES), pupil rounded; two postoculars, subequal or sometimes upper one larger, rounded or subquadrangular, upper postocular in broad contact with supraocular and parietal, lower postocular in contact with anterior temporal and fourth and fifth supralabials; temporals 1 þ 2, elongated, subrectangular; anterior temporal almost the same size as lower posterior temporal, in contact with parietal and both postoculars dorsally, and fifth and sixth supralabial ventrally; lower posterior temporal in contact with sixth and seventh supralabials ventrally. Supralabials seven (on both sides), 5th–7th largest in size; first supralabial in contact with rostral anteriorly, anterior and posterior nasals dorsally, second with posterior nasal and loreal dorsally, third with loreal, preocular and orbit dorsally, fourth with orbit and the lower postocular dorsally, fifth with lower postocular and anterior temporal dorsally, and sixth with anterior and lower posterior temporals dorsally, seventh with lower posterior temporal dorsally and scales of the neck posteriorly. Mental of smaller size, triangular; first infralabial pair larger than mental plate and in broad contact with each other, in contact with anterior chin shields posteriorly; seven infralabials, 1st–3rd in contact with anterior chin shields, ourth infralabial largest in size in contact with both anterior and posterior chin shields; 4th–7th infralabials in contact with gular scales; two larger anterior chin shields, and two smaller posterior chin shields; anterior chin shields in broad contact between them; posterior chin shields bordered posteriorly by six gular scales. Body robust, elongate and subcylindrical; dorsal scales in 17-17-15 rows, all smooth and pointed posteriorly; 169–180 ventrals in males, 183–207 in females; cloacal plate divided. Tail comparatively long (TL 17.0–18.9% of total length in males), robust and thick; subcaudals 46–54, divided. (Bandara et al. 2022: 62) Coloration. In preservative, dorsum dark olive brown, lateral surface paler and yellowish; 30–45 black cross stripes along the body and 6–10 on the tail; the markings on the tail are rudimentary; two inverted V-shaped black markings on the head, (1) the first one on the interorbital region, starting from anterior edge of supraoculars, pointing forward to prefrontal–internasal region; in some individuals the V-shaped marking not complete; (2) the second one on the parietal–frontal region, starting from the gape of the mouth, pointing forward to frontal region, and complete the V shape at the interorbital position; another inverted Y-shaped black marking on the nape, starting from the lateral side of the neck, pointing forward to the level of the interparietal region; dark markings below the eye, usually on the posterior border of fourth and fifth supralabials; all the dark markings are in a range of brown, from chestnut to chocolate brown; venter uniform yellow or cream. In life, same as in preservative, but all the dark markings vary in a range of grey, from olive grey to black; venter uniform cream. Although the juveniles are alike, the adults of this species have two morphs of coloration: (1) the central Indian morph (Fig. 6B) has cross stripes which are comparatively complete laterally; the anterior cross stripes are comparatively wider (prominent in juveniles and subadults) than the rest of the cross stripes; the cross stripes are without distinct white margins in adults. Therefore, we will report this morph of coloration as the ‘‘central Indian morph’’ throughout this study. (2) The northern Indian morph (Fig. 6C) has cross stripes which are comparatively broken and variegated with streaks before disappearing laterally; all the cross stripes are comparatively more or less subequal and thinner than the central Indian morph; the cross stripes are with distinct white margins in adults. Therefore, we will report the morph of coloration as the ‘‘northern Indian morph’’ throughout this study. The central Indian morph of O. russelius has been observed from the lower (southern) portions of the known distribution range (Figs. 6 and 9) of the species. Aside from that, the central Indian morph is parapatric to the northern Indian morph which has a wider distribution in the northern and northeastern Peninsular India. The central Indian morph has been observed from the southern parts of Andhra Pradesh, western parts of Chhattisgarh, eastern parts of Maharashtra, Madhya Pradesh, western parts of Jharkhand, and the southern parts of Uttar Pradesh, while the northern Indian morph has been observed from the northern parts of Andhra Pradesh, eastern parts of Chhattisgarh, West Bengal, eastern parts of Jharkhand, Bihar, northern parts of Uttar Pradesh, Haryana, and Punjab states). The juveniles of all members of this species complex have distinct white margins which gradually disappear during development, but this has an exception in the northern Indian morph of O. russelius (Fig. 5). The lectotype of O. russelius is a juvenile; hence it could be either of the central Indian morph or northern Indian morph as juveniles are alike in both morphs. Andhra Pradesh seems to be an area inhabited by both morphs sympatricly and shares similar suitable habitats where both morphs can inhabit. Also, the type locality, Visakhapatnam, placed in Andhra Pradesh and the area in the year 1796 at the time of Russell, could also have been a much wider area than is recognized nowadays. Therefore, it is possible that the individual (now lectotype) collected by Russell belongs to one or the other of these morphs, and here we do not intend to assign the lectotype of O. russelius to one of them. However, we could locate several adult individuals (not collected) from the vicinity of type locality of O. russelius, Visakhapatnam, in eastern Peninsular India, and they were more similar to the central Indian morph in body coloration. Therefore, with our current understanding, here we treat these two populations as color morphs of O. russelius and we leave it to future taxonomic workers to reevaluate the interpopulation distinctions with integrative taxonomic approaches. Until then these populations will remain named O. russelius. (Bandara et al. 2022: 63) |
| Comment | Synonymy: this species was called Oligodon arnensis during most of its history. Distribution: see map in Bandara et al. 2022: 65 (Fig. 10). |
| Etymology | Named after Patrick Russell, a British medical doctor (see B |
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