Hebius lacrima, Purkayastha & David, 2019

Purkayastha, Jayaditya & David, Patrick, 2019, A new species of the snake genus Hebius Thompson from Northeast India (Squamata: Natricidae), Zootaxa 4555 (1), pp. 79-90 : 81-83

publication ID

https://doi.org/ 10.11646/zootaxa.4555.1.6

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scientific name

Hebius lacrima

sp. nov.

Hebius lacrima spec. nov.

( Figs. 1 View FIGURE 1 & 2 View FIGURE 2 )

Holotype. VR/ERS/ZSI/610, adult male, from Basar (27.980559°N, 94.688496°E), West Siang District , State of Arunachal Pradesh, India, at ca. 600 metres a.s.l. Collected by a villager, preserved in concentrated formalin and subsequently given to Jayaditya Purkayastha, 7 August 2010. GoogleMaps

Diagnosis. A species of the genus Hebius characterized by combination of the following characters: (1) body elongate; (2) tail amounting for 30.1 % of the total length; (3) 24 gradually enlarged maxillary teeth, followed, with a diastema, by 3 distinctly enlarged posterior teeth; (4) nostrils lateral; (5) internasals broad anteriorly; (6) 2 preoculars; (7) 1 anterior temporal, (8) 19–19–17 dorsal scale rows, distinctly keeled except scales of the 1 st rows, smooth but distinctly enlarged; (9) 147 ventrals, not keeled (+ 2 preventrals); (10) anal divided; (11) 89 subcaudals; (12) a white stripe extending on the middle of supralabials from the edge of rostral and 1 st SL to the anterior half of the 6 th SL just below the eye; a second stripe, slightly higher on the labials and temporal regions than the first one, extends from the 7 th SL to the 9 th SL then beyond the angle of jaw to the nape, producing a short V-like chevron; (13) a dark area on the posterior half of 6 th SL, separating the two white stripes; (14) dorsum dark greyish-brown variegated with blackish-brown blotches, without stripe or aligned dorsolateral dots; (15) venter ivory with a large, elongate blotch parallel to the body axis near the tips of each ventral, forming a discontinuous ventrolateral stripe.

Description of holotype. Body moderately stout; head average (3.6% of SVL), distinct from the neck; snout long, flattened, 34.7% of HL, 1.7 times as long as horizontal diameter of the eye, blunt from above, subrectangular in profile; nostril lateral, crescentic, piercing in the middle of divided nasal in its lower half; eye moderately sized, diameter 1.5 times greater than distance between its inferior margin and edge of upper lip; pupil round; tail cylindrical and tapering.

Size. SVL: 340 mm; TaL: 147 mm; TL: 487 mm; HL: 12.4 mm; ratio TaL/TL: 0.301.

Dentition. A total of 27 maxillary teeth: 24 gradually enlarged + 3 distinctly enlarged posterior teeth, separated from anterior teeth by a short diastema.

Hemipenis. The organ was examined in situ. As it was in very bad condition and brittle because of the formalin used to preserve the specimen, we could observe only its general features. Hemipenis short, reaching the 5 th subcaudal, simple and seemingly smooth.

Body scalation. DSR: 19 – 19 – 17, not notched at their posterior extremity, distinctly keeled with a narrow, sharp keel, more keeled on posterior half of body except scales of 1 st DSR, all smooth and enlarged.

Dorsal scale row reduction:

4+5 Ą 4 (93) (left) 19 ———————————17 4+5 Ą 4 (97) (right)

147 VEN (+ 2 preventrals); 89 SC, all paired. Anal divided.

Length of the portion of tail with 6 dorsal scale rows (expressed in number of subcaudals; see Malnate & Underwood 1988): 31; length of the portion of tail with 4 scale rows: 24. Ratio Length 6 rows / Length 4 rows: 1.29.

Head scalation. Rostral hexagonal, wider than high; nasals subrectangular, longer than high, divided below the nostril, with crescentic, laterally opening nostril in its middle; internasals subtriangular and barely narrowing anteriorly, 1.1 times as long as wide and about 0.95 times as wide anteriorly than posteriorly; prefrontals rectangular, almost subequal, in contact with loreal; frontal hexagonal, large, 1.45 times as long as wide, with apex directed posteriorly, 1.8 times longer than suture between prefrontals; parietals twice as long as wide, in contact along a length 1.13 times as great as frontal length; 1/1 loreal, small, rectangular, elongate horizontally, 0.9 time as high as long, in broad contact with nasal; 2/2 preoculars; 3/3 postoculars, upper one much larger than the two lower ones; 9/10 supralabials, 1 st –3 rd in contact with nasal, 3 rd –4 th in contact with loreal, 4 th –6 th entering orbit, 8 th –9 th / 7 th – 8 th largest; temporals: 1+1 / 1+1, anterior one large and elongate; 9/10 infralabials, first pair in contact behind the mental, 1 st –4 th IL in contact with anterior chin shields; posterior chin shields longer than anterior ones, followed by one pair of gulars.

Coloration in alcohol. Body dark greyish-brown above, with scales irregularly marbled with blackish-brown and cream spots; on each side, three rows of irregular, faint dark blotches, not vertically aligned, usually on 3 rd, 5 th and 9 th DSR; on each side of the anterior part of the body, a short dorsolateral row made of a total of six cream, elongate spots along a length equal to about 2.5 head lengths behind the nape region; scales of the first twelve scales of the 1 st DSR ivory, producing a short, conspicuous, ventrolateral stripe; the ivory area of scales of the 1 st DSR decreases quickly in size.

Head dark brown above and on its sides, somewhat paler on the temporal region, with irregular paler brown vermiculation and some scattered beige dots; a short cream sagittal line just on the occipital region behind parietal suture; rostral brown; a broad but irregular, pure white stripe extends from the posterior edge of the rostral to the anterior half of 6 th SL across the lower part of nasal, the lower edge of loreal and the central part of 1 st –5 th supralabials, covering about one third of the height of these supralabials with their upper and lower parts dark brown; posterior half of 6 th SL, just below the eye, dark brown, looking like a “tear” interrupting the white lateral stripe, the limit between the anterior white stripe and the dark area being curved towards the snout; a second pure white stripe, slightly higher on the head side than the anterior one, extends from the upper half of 7 th SL across the central part of 8 th and 9 th SL up to the corner of the mouth then farther on the nape, thick along a length of three or four scales then narrow, directed obliquely upwards, the branch of each side producing a conspicuous V-like chevron on the neck; eye black. The chin and throat are ivory; anterior chin shields marbled with irregular brown areas; mental and infralabials heavily marked with blackish-brown spots.

The venter is ivory; at the base of the triangular tip of each ventral a conspicuous, elongate blackish-brown blotch forming a discontinuous dark ventrolateral stripe that extends along the whole of the body; the ivory tip of each ventral contrasts with both the inner dark brown blotch of each ventral and the dark color of scales of the 1 st DSR posterior to the 12 th ventrals, producing a pale ventrolateral stripe. Under surface of tail ivory, with the outer part and tip of each subcaudal blackish-brown, producing a dark ventral stripe not separated from the dark color of the dorsal surface of the tail.

Etymology. The species nomen derives from the Latin noun lacrima (- ae), meaning “a tear”, a reference to the dark area under the eye looking like a black tear which interrupts the white supralabial stripe. This species nomen is a noun in apposition and not an adjective.We suggest the following common names: Crying Keelback (English).

Ecological notes. The single known specimen was obtained from a rice field alongside a hill slope ( Fig. 3 View FIGURE 3 ) in the outskirt of the city of Basar ( Fig. 4 View FIGURE 4 ), so in a heavily disturbed area. A small stream was flowing adjacent to this field. An indigenous agricultural practice called Jhum (shifting) cultivation was done in the hills adjacent to the rice field.













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