Hypnale nepa Laurenti 1768
Creators: name: Maduwage, Kalana
name: Silva, Anjana
name: Manamendra-Arachchi, Kelum
name: Pethiyagoda, Rohan
Publisher: name: Zenodo
Year: 2009
Subjects: Biodiversity
Taxonomy
Animalia
Chordata
Reptilia
Squamata
Viperidae
Hypnale
Hypnale nepa

description: Hypnale nepa (Laurenti, 1768)
(Fig. 4; Fig. 5; Table 2)
Coluber nepa Laurenti, 1768 Hypnale walli Gloyd, 1977 b
Neotype. (Here designated), WHT 6515, male, 367 mm SVL, Agra Arboretum, Agarapatana, 06º50’N, 80º40’ E, alt. 1665 m, coll. S. V. Nanayakkara, 0 4 III 2006.
Measured material. Males, 2 ex. (WHT 5836, MMB, 15 IX 2000; WHT 5953, MMB, 0 5 XII 2001), 238 mm, 245 mm, SVL, respectively; females, 6 ex. (WHT 5833, DG, 10 VIII 1998; WHT 5834, MMB, 20 VI 2001; WHT 5845, DG, I 1999; WHT 6081, MMB, 10 IV 2004, WHT 6082, MMB, 0 3 II 2004; WHT 5954, KM, 25 XI 2003), 142 mm SVL, 342 mm SVL, 235 mm SVL, 315 mm SVL, 292 mm SVL, damaged specimen, respectively, Agra Arboretum, Agarapatana, 06º50’N, 80º40’ E, alt. 1665 m. Females, 3 ex. (WHT 2002.S, DG, 0 8 XI 1993; WHT 2002.L, DG, 0 8 XI 1993; WHT 5838, SB and KW, 20 IV 2000), 263 mm, 315 mm, 278 mm SVL, respectively, Adam’s Peak, 06º49’N, 80º30’ E, alt. 1830 m. Female 1 ex. (WHT 5837, KM and AS, 0 7 II 2003), 292 mm SVL, Hakgala, 06º55’N, 80º49’ E, alt. 1850 m.
Diagnosis. Hypnale nepa is distinguished from its congeners by a combination of the following characters: snout tip flattened or moderately raised, with 5–15 minute scales forming a wart-like protuberance at tip of snout (Fig. 4 a, b); 12–25, heterogeneous scales on internasal-prefrontal region (Fig. 4 b); 6–9 scales surround eye (supraocular + 2 postoculars + 0–3 suboculars + 2 preoculars + postfoveal) (Fig. 4 a); 4 or 5 scales surround maxillary pit—lower preocular + postfoveal + lacunal + upper edge of second supralabial, or lower preocular + postfoveal + lacunal + upper posterior border of second supralabial and a small scale above lacunal (see Fig. 4 a); 1–3 scales between postfoveal and 2nd and 3rd supralabials (Fig. 4 a); postocular, 1st lower temporal, and 4th and 5th supralabials surround a rhomboid (‘diamond’-shaped) scale of similar size (Fig. 4 a). Supralabials 7 or 8; a lacunal scale present; mid-dorsal scales smooth (Fig. 4 g); ventrals 122–134; subcaudal series divided medially, with 27–41 scales. Hemipenial lobe with large spines on proximal twothirds of its length; distal third with calyces, not spinous (Fig. 4 d).
Hypnale nepa is distinguished from H. hypnale by possessing (vs lacking) a wart-like protuberance at the tip of the snout; having 1–3 (vs no) scales between the postfoveal and the 2nd and 3rd supralabials; having the postocular, 1st lower temporal, and 4th and 5th supralabials separated by a rhomboid scale of similar size (vs in contact); having the mid-dorsal scales smooth (vs all costal scales keeled); possessing 122–134 (vs 141– 158) ventrals; and having the hemipenial lobes with large spines on their proximal two-thirds (vs lobes smooth, lacking spines).
It is distinguished from H. zara by having the snout tip flattened or only slightly raised (vs snout distinctly elevated); 12–25 (vs 18–39) heterogeneous scales on internasal-prefrontal region; 4–5 (vs 3) scales surrounding maxillary pit; 1–3 (vs no) scales between postfoveal and 2nd and 3rd supralabials; having the lower postocular, 1st lower temporal, and 4th and 5th supralabials surrounding a rhomboid scale of similar size (vs in contact, no scale between them); a lacunal scale present (vs absent); the mid-dorsal scales smooth (vs all costal scales keeled); 122–134 (vs 134–157) ventrals; and the hemipenial lobe with large spines (vs without spines) on proximal two-thirds of its length.
It is distinguished from Hypnale sp. ‘amal’ by possessing (vs lacking) a wart-like protuberance on the snout tip; having 1–3 (vs no) scales between postfoveal and 2nd and 3rd supralabials; the lower postocular, 1st lower temporal, and 4th and 5th supralabials separated by a rhomboid scale of similar size (vs in contact, no scale between them); 7 or 8 (vs 9) supralabials; first infralabials on either side separated by a median suture (vs medially fused); mid-dorsal scales smooth (vs all costal scales keeled); 122–134 (vs 151) ventrals; hemipenial lobe with large spines on proximal two-thirds of its length (vs not spinous); two rows of distinct, bilaterally symmetrical blotches meeting on dorsal midline (vs a distinct purple-brown paravertebral stripe, about 3 scales wide, from neck to level of vent).
TABLE 2: Measurements as a proportion of snout-vent length and head length of Hypnale nepa, H. zara and H. sp. ‘amal’. Abbreviations: SVL, snout-vent length;TL, tail length; HL, head length; HW, head width; SL, snout legnth; FL, frontal legth; FW, frontal width; PL, parietal length; PL, parietal width; SU, supraocular length; SW, supraocular width; SS, frontal supraocular suture. See text for details of material measured.
H. nepa H. zara H. nepa H. zara H. sp. ‘amal’
male male female female male
N mean range s.d. Nmean range s.d. N mean range s.d. N mean range s.d.
Description. Based on neotype (WHT 6515). Snout tip distinctly raised, with 5 small scales forming a wart-like protuberance at its tip; 16 scales on internasal-prefrontal region, heterogeneous, irregularly arranged (Fig. 4 a, b); internasals smaller than prefrontals, distinct (Fig. 4 b); prefrontals distinct (Fig. 4 b), somewhat displaced; internasals separated from each other and from rostral by a scaly, wart-like protuberance (Fig. 4 b); prefrontals distinguishable, anteriorly in contact with each other, posteriorly not in contact (Fig. 4 b); prefrontals separated from frontal and supraoculars by 7 smaller scales (Fig. 4 b); upper preocular, loreal, and nasals extend over canthal ridge, visible from above (Fig. 4 a); rostral longer than wide, obtusely pointed, scarcely visible from above (Fig. 4 a); nasal entire (Fig. 4 a); loreal acutely pointed anteriorly, its posterior margin broad, extending dorsally across canthus (Fig. 4 a); 2 preoculars (Fig. 4 a); 2 postoculars (Fig. 4 a); a single subocular, reaching postfoveal; eye encircled by 7 scales: 2 preoculars + supraocular + 2 postoculars + subocular + postfoveal (Fig. 4 a). Lacunal present (Fig. 4 a). Maxillary pit bordered by 4 scales: lower preocular, postfoveal, lacunal and upper posterior border of 2nd supralabial (Fig. 4 a). Two small scales between postfoveal and 3rd supralabial (Fig. 4 a); supralabials 7, not reaching eye (Fig. 4 a); infralabials 8 (Fig. 4 c); 1st supralabial triangular, its apex divided into a small scale on left side (Fig. 4 a), undivided on right side; temporals 2+2+2, smooth, those on lower row greatly enlarged. Lower postocular, 1st lower temporal, and 4th and 5th supralabials surround a similar-sized rhomboid (‘diamond-shaped’) scale. Numerous small scales present behind parietals. Mental subtriangular. A single pair of chin shields, slightly longer than wide (Fig. 4 c); infralabials I, II and III in contact with chin shields; mental and chin shields separated from each other by infralabial I. Gular scales in median series, 4; on lateral series, 6 (Fig. 4 c). Costal scales at mid-body 17. Dorsal scales smooth (Fig. 4 g). Paired apical pits present, inconspicuous. Ventrals 122; subcaudal series divided medially, with 41 scales; anal scale partially divided; 2 sub-anal scales on each side. Rows of costal scales up to 9th ventral on right side and 8th ventral on left, 19; 17 rows thereafter (including mid-body) up to 109th ventral on right side, 102nd on left, following which 15 rows up to anus.
Costodorsal reduction (WHT 6515):
4+5(9) 3+4(109)
19 ————17—————15 (122)
4+5(8) 3+4(102)
Hemipenes moderately long, slender, deeply forked; prominent spines present on proximal two-thirds of length of each lobe, the proximal-most ones longer than the distal-most ones; spines absent on distal third (Fig. 4 d); denticulated calyces cover distal portion of lobe; sulcus spermaticus shallow, its wall smooth.
Mensural data (see also Table 2). Measurements of neotype: SVL, 367 mm; TL, 80 mm (21.8% of SVL); HL, 24.2 mm (6.6% of SVL); SL, 7.0 mm (28.9% of HL); FL, 4.3 mm (17.8% of HL); FW, 3.7 mm (15.3% of HL); PL, 7.3 mm (30.2% of HL); PW, 4.1 mm (16.9% of HL); SU, 5.1 mm (21.1% of HL); SW, 3.9 mm (16.1% of HL); SS, 2.7 mm (11.2% of HL).
Variation (in material examined). Tip of snout flattened to moderately raised; wart like protuberance comprises 5–15 small scales; 12–25 scales on internasal-prefrontal region. Prefrontals distinguishable or indistinguishable; when distinguishable, prefrontals in contact along their entire length, partially or altogether separated from each other. Prefrontals separated from frontal and supraoculars by 5–10 small scales. Nasal entire or partially divided above nostril; suboculars absent or 1–3: when absent, lower postocular reaches postfoveal. Eye encircled by 6–9 scales; a small scale either present or absent at upper angle of lacunal, below loreal and upper preocular. Maxillary pit bordered by 4 scales (lower preocular, postfoveal, lacunal and upper posterior border of second supralabial) or by 5 scales (lower preocular, postfoveal, lacunal, upper posterior border of second supralabial and small scale above lacunal). Small scales between postfoveal and 3rd supralabial, 1–3. A small triangular scale either present or absent beneath subocular, between 3rd and 4th supralabials. Supralabials, 7 or 8; apex of 1st supralabial divided or undivided; when undivided, 1st supralabial extends upwards to reach loreal. Infralabials I and II, or I, II and III in contact with chin shields; gular scales in median series, 4–6; gular scales in lateral series, 6–9. Costal scales smooth or keeled. Ventrals 122–131 in males, 125–134 in females; subcaudal series with 37–41 scales in males, 27–40 in females; anal scale entire or partially divided; sub-anal scales on each side, 1–3. In WHT 5953, first two proximal-most scales of subcaudal series undivided, with 35 scales in divided series.
Coloration. In life, dorsal ground colour varies from yellowish-tan to dark brown. Two rows of distinct sub-oval or sub-triangular blotches meet on dorsal midline, bilaterally symmetrical (especially on tail), sometimes displaced longitudinally on body (see Fig. 5 b, c). A dark stripe present across eye and cheek. Overall colour of venter much lighter than that of dorsum, sometimes light ash-grey.
Natural history notes. Hypnale nepa occurs frequently and widely in the central hills of Sri Lanka, where it is restricted to an altitudinal range of ~ 1250–1,850 m a.s.l (see Fig. 4 i). It was also recorded from tea plantations, and does not appear to be adversely affected by forest loss in the island’s central highlands. The only putative record of a specimen outside this range is that of the holotype of H. walli, stated to have been collected from Kanneliya in the south-western lowlands near Galle, which evidently was a mislabelled specimen (see Introduction).
We observed Hypnale nepa to be more active at night, with specimens found in daytime being under logs and rocks among leaf litter in both undisturbed and secondary forest, more commonly at forest edges. It appears that H. nepa also feeds on other snakes: the gut of the neotype contained two Common rough-sides (Aspidura trachyprocta, Colubridae). In a study of gut contents, Wall (1905) noted that Lygosoma taprobanense appeared to be the staple food of this species at Hakgala, together with soft-shelled eggs [of serpents], frogs and rough-sides.
A gravid female (WHT 6147, 243 mm SVL) collected from near Hakgala on 0 6 VIII 2004 gave birth to five live young with adult coloration, measuring 116 mm, 115 mm, 126 mm, 108 mm, and 117 mm TTL. Week-old juveniles were aggressive, frequently striking when alarmed. A gravid female (WHT 6081, 315 mm SVL) collected at the Agra Arboretum on 10 April 2004 contained eight embryos (75–95 mm TBL) with yolk sacs and adult coloration. Another gravid female (382 mm TBL, WHT 5834), also collected at the Agra Arboretum on 2 June 2001, contained seven fully-developed young (120–123 mm TBL), with the yolk sacs fully absorbed and showing adult coloration.
description: Published as part of Maduwage, Kalana, Silva, Anjana, Manamendra-Arachchi, Kelum & Pethiyagoda, Rohan, 2009, A taxonomic revision of the South Asian hump-nosed pit vipers (Squamata: Viperidae: Hypnale), pp. 1-28 in Zootaxa 2232 on pages 10-15, DOI: 10.5281/zenodo.190308