Hebius nigriventer (WALL, 1925)
Can you confirm these amateur observations of Hebius nigriventer?
|Higher Taxa||Colubridae (Natricinae), Colubroidea, Caenophidia, Alethinophidia, Serpentes, Squamata (snakes)|
|Synonym||Natrix nigriventer WALL 1925: 588|
Natrix venningi — WALL 1926: 560 (part) (nec Tropidonotus venningi WALL 1910)
Natrix venningi — SMITH 1943: 286 (part)
Tropidonotus venningi — Werner 1929: 24 (part) (nec T. venningi WALL 1910)
Amphiesma venningi — KOU 1985: 160 (part) (nec T. venningi WALL 1910)
Amphiesma venningi — ZHAO & JIANG 1986: 239 (?; identification uncertain)
Amphiesma venningi — ZHAO & ADLER 1993: 228 (part)
Amphiesma venningi — ZHAO et al. 1998: 89 & 90 (part)
Amphiesma venningi — ZHANG 1999: 430 (?)
Amphiesma venningi — ZHAO et al. 2000b: 205
Amphiesma venningi — ISKANDAR & COLIJN 2001: 98 (mention from China)
Amphiesma venningi — HE & ZHOU 2002: 167 (part)
Amphiesma venningi — JI 2002: 184
Amphiesma venningi — ZHAO 2006: (Vol. I) 174 (part), (Vol. II) 97: Fig. 59
Amphiesma venningi — DAVID et al. 2007: 54ff (part)
Amphiesma venningi — SHARMA 2007: 207 (in part)
Amphiesma venningi — YANG & RAO 2008: 268
Amphiesma venningi — LUO et al. 2010: 74
Amphiesma venningi — ZHANG 2011: 277 (?)
Amphiesma venningi — WALLACH et al. 2014: 33 (in part)
Amphiesma Venrrinig [sic] — KOU & ZHANG 1987: 364
Hebius nigriventer — DAVID et al. 2021
|Distribution||Myanmar (Kachin), China (Yunnan)|
Type locality: “Huton, Bhamo District (30 miles north-east of Bhamo; circa 4,500 feet; Lat. circa 97°33; Long. Circa 24°24”, now Hutung, Bhamo District, Kachin State, Myanmar
|Types||Holotype. BMNH 1922.214.171.124, adult female; collected by Father Gilhodes, June 1924.|
|Diagnosis||Diagnosis. A moderately sized species of the genus Hebius characterized by the combination of (1) 17(exceptionally 19)-17-15–17 dorsal scale rows, moderately keeled at midbody, strongly keeled posteriorly but 1st DSR smooth; (2) dorsal scales around the base of the tail strongly keeled; (3) head moderately distinct from the neck; (4) eye size moderate; (5) maxillary teeth 28–33, the last two moderately enlarged; (6) tail long, with a ratio TaL/TL at least equal to 0.29 in females, up to 0.37 in males; (7) VEN 155–168; (8) SC 105–143; (9) 2 prefrontal scales, (10) anterior temporal elongate, rectangular; (11) venter entirely very dark, i.e., blackish–brown or black, sometimes with two, narrow longitudinal paler stripes, at the exception of a middle stripe pale but heavily blotched with dark hues anteriorly, extending on 5–15 ventrals; (12) dorsal colour very dark, dark brown, very dark greyish-brown or blackish-brown; (13) dorsum background either uniform or with a subdued chequered dorsal pattern made of large, diffuse, rectangular darker blotches on 4th–5th and 7th–8th DSR; (14) on each side, a series of large, cream or pale yellowish-brown (bright orange, rusty-red or reddish-brown in life), rectangular blotches, higher than long anteriorly then more elongate, forming a conspicuous, dorsolateral chain of blotches on 5th–6th DSR throughout the length of the body, becoming smaller posteriorly and turning to an irregular stripe posteriorly; (15) a dark postocular streak usually present; and (16) a short, oblique yellowish-brown or yellow-ochre streak (bright orange or rusty-red in life) above the corner of the mouth and a large blotch of the same colour on the side of the neck (David et al. 2021).|
Comparisons. Hebius nigriventer differs from H. taronensis, with which it might be sympatric in northern Myanmar (Kachin State) by (1) the dorsal general colour and pattern, i.e, a very dark background colour with a uniform or weakly and partly chequered pattern vs. a dark background with pale and dark spots or blotches forming a complex speckled or mottled pattern in H. taronensis; (2) a conspicuous dorsolateral chain or stripe of bright, orange or rusty-brown blotches vs. a series of small pale yellowish-brown or ochre-brown dorsolateral blotches on the anterior part of the body; (3) venter nearly entirely very dark, i.e. blackish-brown or black, vs. venter both pale and dark, i.e., with a pale background on its anterior part with the anterior half of each ventral brown or blackish-brown, producing a pattern of irregular dark crossbands, and venter nearly uniformly very dark ochre-brown, dark brown or blackish-brown on its posterior part; (4) a longer tail, ratio TaL/TL 0.29–0.37 vs. 0.25–0.29 in H. taronensis, especially in males: 0.32–0.37 vs. 0.25–0.29; (5) more subcaudals, 105–143 vs. 92–104 SC; (6) fewer ventrals in males, 156–168 vs. 171–175 VEN; (7) a difference in the ratio VEN/SC: 1.16–1.59 vs. 1.66–2.02; and (8) the number of postoculars, usually 2, rarely 3 in H. nigriventer vs. always 3 in H. taronensis.
H. nigriventer differs from H. venningi, by (1) the dorsal general colour and pattern: a very dark background colour vs. dorsum grey, greyish-brown or, more rarely dark brown, with a distinct chequered pattern of darker blotches in H. venningi; (2) a conspicuous dorsolateral chain or stripe of bright, orange or rusty-brown blotches vs. a dorsolateral series of irregular blotches, yellow-ochre or yellowish-brown (bright yellow-ochre in life), enlarged and forming a chain on the first quarter to third of the body, usually vanishing after midbody in H. venningi; (3) venter entirely very dark, blackish-brown or black, sometimes with two, narrow longitudinal paler stripes vs. venter widely pale in its middle part along at least the anterior part of the body, laterally clouded or dotted with dark grey or dark brown, never entirely dark; (4) the position of the reduction to 6 scale rows around the tail in males: SC 9–14 vs. SC 19–24; and (5) the number of postoculars, 2, rarely 3, vs. always 3 in H. venningi.
The list of these characters may not clearly express the visual differences between H. nigriventer, an overally dark species with highly contrasted bright orange dorsolateral blotches, and H. venningi, a usually paler species, more “grey”, with a much more subdued chequered dorsal pattern. It should be noted that specimen CAS 233206 has a very dark brown background dorsal colour and a venter pale only along the first 10–15 ventrals. However, the dorsal chequered pattern and the lack of the conspicuous dorsolateral bright orange or rusty-brown blotches make it undoubtedly referable to H. venningi.
Lastly, H. nigriventer is morphologically quite similar to H chapaensis. Differences between these two species are given below in the account of H. chapaensis (David et al. 2021).
Description: more details in David et al. 2021.
Sexual dimorphism: David et al. 2021
|Comment||Synonymy: after David et al. 2021 (also see there for references). Bourret 1936: 55 synonymized N. nigriventer with Natrix venningi. David et al. 2021 revalidated it. Figure 59-1 in Zhao 2006: Vol. II: 97 depicts a Hebius bitaeniatus.|
Illustration: Yang & Rao 2008: 268 (Figure: H. nigriventer), 269 (Table 58: H. nigriventer).
Similar species: H. venningi, H. chapaensis.
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