Hypnale hypnale ( Merrem, 1820 )

Maduwage, Kalana, Silva, Anjana, Manamendra-Arachchi, Kelum & Pethiyagoda, Rohan, 2009, A taxonomic revision of the South Asian hump-nosed pit vipers (Squamata: Viperidae: Hypnale), Zootaxa 2232, pp. 1-28 : 4-10

Hypnale hypnale ( Merrem, 1820)

( Figs. 1–3 , Table 1)

Cophias hypnale Merrem, 1820

Trimeresurus ceylonensis Gray, 1842 Hypnale affinis Anderson, 1871

Ancistrodon millardi Wall, 1908

Neotype (here designated). Female, BNHS 2531: 759, 350 mm SVL, Castle Rock in Karnataka State, India, 15º23’52”N, 74º19’56” E, alt. 620 m, coll. H. S. Wise, 31 XII 1907 (lectotype of Ancistrodon millardi Wall, 1908 , here designated).

Measured material ( Sri Lanka). Male, 1 ex. (WHT 5947, KM and SK, 12 XI 2003), 309 mm SVL; females, 2 ex. (WHT 5948, KM and SK, 12 XI 2003, WHT 5949, KM and SK, 12 XI 2003), 352 mm, 408 mm SVL, respectively, Carsfield Estate, Maspotha, Kurunegala, 07º33’N, 80º18’ E, alt. 85 m. Females, 2 ex. (WHT 5930, MMB, 0 8 I 1995, WHT 1594, MMB, 0 1 VI 1996), 364 mm, 293 mm SVL, respectively, Navinna, Galle, 06º04’N, 80º13’ E, alt. 15 m. Female, 1 ex. (WHT 5858, MMB, 0 2 VIII 1995), 337 mm SVL, Hapugala, Galle, 06º04’N, 80º12’ E, alt. 5 m. Male, 1 ex. (WHT 5852, AW, 15 IX 1998), 311 mm SVL; female, 1 ex. (WHT 5939, AW, 15 IX 1998), 377 mm SVL, Kalegana, Galle, 06º03’N, 80º12’ E, alt. 10 m. Female, 1 ex. (WHT 5850, MMB, 0 8 VIII 1995), 305 mm SVL, Godakanda, Galle, 06º05’N, 80º13’ E, alt. 15 m. Males, 2 ex. (WHT 5856, MMB, 14 VIII 1995, WHT 5855, MMB, 0 2 VIII 1995), 334 mm, 325 mm SVL, respectively; Navinna, Galle, 06º04’N, 80º13’ E, alt. 15 m. Female, 1 ex. (WHT 5931, DK, 10 VII 1997), 292 mm SVL, Imaduwa, Galle, 06º02’N, 80º23’ E, alt. 45 m. Females, 2 ex. (WHT 5938, RW, 20 V 1998, WHT 5945, SB, 12 III 1997), 180 mm, 260 mm SVL, respectively, Galle, 06º03’N, 80º13’ E, alt. 2 m. Male, 1 ex. (WHT 5851, MMB, 17 II 1995), 278 mm SVL, Uluvitike, Galle, 06º05’N, 80º11’ E, alt. 15 m. Female, 1 ex.

(WHT 5853, AS and KM, 0 1 IX 2003), 323 mm SVL, Kegalle, 07º15’N, 80º21’ E, alt. 90 m. Males, 3 ex. (WHT 1886.S, DG, 0 1 IX 1997, WHT 5841, MMB and DG, 10 IX 1997, WHT 5843, KMA and SVN, 0 2 V 1998), 272 mm, 233 mm, 274 mm SVL, respectively; females, 2 ex. (WHT 1886.L, DG, 0 1 IX 1997, WHT 5842, MMB and DG, 10 IX 1997), 380 mm, 302 mm SVL, respectively, Puwakpitiya, (Knuckles), 07º34’N, 80º44’ E, alt. 414 m. Males, 2 ex. (WHT 6086, KM and TM, 19 I 2004, WHT 5946, KM and TM, 14 V 2000), 223 mm, 277 mm SVL, respectively; females, 4 ex. (WHT 5936, KM, 22 III 2000, WHT 6083, KM, 19 I 2004, WHT 6085, KM, 19 I 2004, WHT 6084, KM, 19 I 2004), 303 mm, 247 mm, 200 mm, 215 mm SVL, respectively, Ambalangoda, 06º16’N, 80º04’ E, alt. 5 m. Male, 1 ex. (WHT 2328, PR, 0 1 XII 1998), damaged, Piliyandala, near Colombo, 06º48’N, 79º55’ E, alt. 12 m. Female, 1 ex. (WHT 5844, KMA, 28 IX 1998), 343 mm SVL, Malambe, Colombo, 06º54’N, 79º57’ E, alt. 30 m. Female, 1 ex. (WHT 0 252, PF, 11 X 1993), 330 mm SVL, Kochchikade near Negombo, 07º16’N, 79º51’ E, alt. 2 m. Male, 1 ex. (WHT 5944, KW, 0 5 I 2003), 343 mm SVL, Avissawella, 06º57’N, 80º12’ E, alt. 90 m. Male, 1 ex. (WHT 6155, MMB), 310 mm SVL, Wasgomuwa, 07º43’N, 80º59’ E, alt. 60 m. Female, 1 ex. (WHT 5957, AS and KM, 25 XI 2003), 415 mm SVL, Kandy, 07º17’N, 80º38’ E, alt. 465 m. Female, 1 ex. (WHT 5955), 119 mm SVL, Ritigala, 08º07’N, 80º38’ E, alt. 200 m. Female, 1 ex., (WHT 5937, KM, 15 I 2003), 285 mm SVL, Ginigathhena, 06º59’N, 80º29’ E, alt. 580 m. Female, 1 ex. (WHT 5839, DG, 1993), 320 mm SVL, Kithulgala, 06º59’N, 80º24’ E, alt. 150 m. Female, 1 ex. (WHT 0644), 296 mm SVL, Pussella Estate, Parakaduwa, 06º49’N, 80º19’ E, alt. 60 m. Female, 1 ex. (WHT 5962, KM, 25 XI 2003), 134 mm SVL, Nawalapitiya, 07º04’N, 80º32’ E, alt. 610 m. Female, 1 ex. (WHT 6955, KM and AS, 15 VI 2006), 275 mm SVL, Kadugannawa, 07º15’N, 80º31’ E, alt. 500 m. female, 1 ex. (WHT 6508), 207 mm SVL, Peradeniya, 07º15’N, 80º36’ E, alt. 460 m.

Measured material ( India). Males, 2 ex. ( BNHS 2532, HSW, 31 VII 1907, BNHS 2531. 758, HSW, 31 VII 1907), 169 mm, 246 mm SVL; females, 3 ex. ( BNHS 2531. 757, HSW, 31 VII 1907, BNHS 2531. 759, HSW, 31 VII 1907, BNHS 2530, FW), 343 mm, 350 mm SVL, 242 mm SVL Karwar, Karnataka State, India, 15º24’N, 74º20’E, alt. 620 m. Female, 1 ex. ( BNHS 3149, AJ, 28 XI 1984), 271 mm SVL, Kalakkad Hill, Tamil Nadu, 8º30’N, 77º34’E. Female, 1 ex. ( BNHS 2537, DM, IV 1962), 338 mm SVL, Karimba, Palghat [Kalakkad]. Female, 1 ex. ( BNHS 2536, FW), 323 mm SVL, ‘Phillor’. Female, 1 ex. ( BNHS 2526, HB, 13 XII 1927), 315 mm SVL, ‘Palagapandy Estate’ [Kalakkad]. Female, 1 ex. ( BNHS 2535, CF, 10 VI 1910), 308 mm SVL, Coimbatore, 11º00’N 76º58’E?, alt. 400 m.

Diagnosis. Hypnale hypnale is distinguished from its congeners by a combination of the following characters; snout tip not raised, no wart-like protuberance at tip of snout ( Fig. 1 a); 3–5 minute scales between rostral and anterior border of internasals ( Fig. 1 b); 5–15 heterogeneous scales on internasal-prefrontal region ( Fig. 1 b); 6 scales surrounding eye (supraocular + 2 postoculars + 2 preoculars + postfoveal) ( Fig. 1 a); 4–5 scales surrounding maxillary pit (lower preocular + postfoveal + lacunal + upper edge of second supralabial or lower preocular + postfoveal + lacunal + upper edge of second supralabial + loreal) ( Fig. 1 a); 2 postoculars, the upper one small, the lower one crescentic, reaching postfoveal; no scales between postfoveal and 3rd supralabial ( Fig. 1 a); lower postocular, 1st lower temporal, 4th and 5th supralabials in contact, no scale between them. Supralabials, 7 or 8; lacunal present (surrounded by loreal + 1st supralabial + 2nd supralabial + maxillary pit + tip of lower preocular). Costal scales keeled ( Fig. 1 g); ventrals, 141–158; subcaudal series divided medially, with 26–47 scales. Lobes of hemipenes smooth, lacking spines ( Fig. 1 d).

It is distinguished from H. nepa by lacking (vs possessing) a wart-like protuberance at the tip of the snout; lacking scales (vs possessing 1–3 scales) between postfoveal and 3rd supralabial; having the lower postocular, 1st lower temporal, 4th and 5th supralabials in contact, with no scale between them (vs separated by a rhomboid scale of similar size); having the costal scales keeled (vs smooth) in mid-dorsal region; possessing 141–158 (vs 122–134) ventrals; and having the lobes of hemipenes smooth, lacking spines (vs hemipenial lobes with large spines on proximal two-thirds of their length).

Hypnale hypnale is distinguished from H. zara by having the snout tip not raised (vs distinctly elevated); 3–5 minute scales between rostral and anterior border of internasals (vs 10–19 minute scales forming a wartlike protuberance at the snout tip); 5–15 (vs 18–39) heterogeneous scales on the internasal-prefrontal region; 4–5 (vs 3) scales surrounding the maxillary pit; and possessing (vs lacking) a lacunal scale.

It is also distinguished from Hypnale sp. ‘amal’ by having 7–8 (vs 9) supralabials; the first infralabials separated from each other by a median suture (vs medially fused); and two rows of dark, bilaterally symmetrical blotches meeting on dorsal midline (vs a distinct paravertebral stripe, about 3 scales wide, extending from neck to level of vent).

Description. (Based on neotype, BNHS 2531.759). Snout tip horizontal, not notably elevated, without a protuberance at its tip. Five small scales between rostral and anterior border of internasals; scales on internasal and prefrontal region 10, irregularly arranged; internasals small, distinct; prefrontals distinct, somewhat displaced; internasals widely separated from each other by 2 small scales; prefrontals anteriorly in contact, posteriorly separated by a small scale; prefrontals separated from frontal and supraoculars by a row of 5 small scales; upper preocular, loreal and nasal extend over canthal ridge, visible from above; rostral longer than wide, obtusely pointed, scarcely visible from above; nasal partially divided above level of nostril; loreal acutely pointed anteriorly, its posterior margin broad, extending dorsally across canthus; 2 preoculars; 2 postoculars, the upper one small, the lower one reaching postfoveal; eye encircled by 6 scales: 2 preoculars + supraocular + 2 postoculars and postfoveal; lacunal present. Maxillary pit bordered by 4 scales: lacunal, lower preocular, postfoveal and upper edge of 2nd supralabial; supralabials 7, not reaching eye; 1st supralabial extends upwards to reach loreal; apex of 1st supralabial extends upwards to reach loreal, not divided into a small scale; infralabials, 8 on left side, 9 on right side; temporals 2+2+2, smooth, those on lower row greatly enlarged. Numerous small scales present on post-parietal region. Mental subtriangular. A single pair of chin shields, somewhat longer than wide, in contact with infralabials I, II and III. Mental separated from chin shields by infralabial I; median rows of gular scales, 5; lateral rows of gular scales, 6. Rows of costal scales up to 6th ventral on right side and 5th ventral on left, 19; 17 rows thereafter (including mid-body) up to 140th ventral on right side, 139th on left, following which 15 rows up to anus. Costals keeled except for lowermost lateral row; paravertebral scale row not enlarged; paired apical pits present, inconspicuous. Ventrals, 143; subcaudal series divided medially, with 36 scales; anal entire; 2 pairs of subanals.

TABLE 1: Measurements as a proportion of snout-vent length and head length of Hypnale hypnale from Sri Lanka and India. 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.

Hypnale hypnale Sri Lanka Hypnale hypnale India

male female male female Costodorsal reduction (WHT 5852):

4+5(6) 3+2(140)

19————17————15 (143)

4+5(5) 4+3(139)

Hemipenes (based on WHT 5852) ( Fig. 1 d, e, f) moderately long, slender, deeply forked, divided; transverse flounces closely spaced on proximal half of each lobe, without spines, more widely spaced distally, where flounces tend to be angulated to wall of sulcus spermaticus; denticulate flounces surround lobe; sulcus spermaticus deep, its walls in contact; ridge of sulcus spermaticus formed by closely spaced, narrow flounces.

Mensural data (see also Table 1). Measurements of neotype: SVL, 350 mm; TL, 54 mm, (15.4% of SVL); HL, 21.2 mm (6.0% of SVL); HW, 12.0 mm (56.6% of HL); SL, 7.0 mm (33.0% of HL); FL, 4.2 mm (19.8% of HL); FW, 2.7 mm (12.7% of HL); PL, 5.2 mm (24.5% of HL); PW, 3.4 mm (16.0% of HL); SU, 5.1 mm (24.1% of HL); SW, 3.5 mm (16.5% of HL); SS, 2.9 mm (13.7% of HL).

Variation. Small scales on snout tip between rostral and base of internasals 3–5; scales of internasalprefrontal region irregularly arranged; internasals small, distinct; prefrontals distinct, sometimes somewhat displaced; internasals in contact or partially separated, anteriorly in contact, posteriorly separated by a small scale; prefrontals separated from both frontal and supraoculars by a row of 2–6 small scales, or in contact with frontal and supraoculars; nasal entire or partially divided; eye encircled by 6 scales on left side, 7 on right side in WHT 5955 and WHT 5945. Supralabials 7 or 8; 1st supralabial extends upwards, reaching or not reaching loreal; apex of 1st supralabial divided or undivided; infralabials 8 or 9; infralabials I and II or I–III in contact with chin shields. Gular scales in median series 3–7; gulars in lateral series, 6–9. Costal scales on lowermost 1–5 lateral rows smooth. Ventrals 146–157 in males, 141–158 in females. Subcaudal series divided medially, with 39–47 scales in males, 26–43 in females; first 4 proximal subcaudals undivided, with 39 divided subcaudals in series in WHT 5839. Subanal scales in 2 or 3 pairs.

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. 3 b). 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. In India Hypnale hypnale , though widely distributed throughout the Western Ghats (more commonly in the region south of the Palghat Gap) ( Fig. 2 a) from 300–600 m, appears to be relatively infrequently encountered ( Gloyd & Conant, 1990). In Sri Lanka, the species is recorded from coastal areas up to the lower parts (~ 600 m) of the central hills ( Fig. 2 b). The insular population is more abundant in the south-western ‘wet zone’ (rainfall> 2,000 mm yr -1) than in the drier parts of the northern and eastern ‘dry zone’.

Hypnale hypnale is commonly found under stones, logs and leaf litter in and around human settlements, especially in coconut, tea and rubber plantations, and in farmlands. It is significantly more frequent in anthropogenic habitats: we have never recorded this species from within undisturbed forest, though in India several records exist of specimens being found in rainforest (e.g., Inger et al., 1984). In Sri Lanka, H. hypnale is largely nocturnal. Though our own observations suggest that this snake is essentially terrestrial, there are records suggestive of arboreal behaviour (e.g., Wall, 1921; Smith, 1943; Koshy & Inger, 1983).

We have observed several species of skinks and shrews in the gut contents of adult specimens of H. hypnale . Reproduction has been described by de Silva (1984) and behaviour in captivity by Henry (1925), but it is impossible to know exactly which species they observed. Henry (1925) described a captive specimen from Matugama in the wet-zone lowlands (presumably H. hypnale or H. zara ) devouring another hump-nosed pit viper he introduced into its terrarium from Medamahanuwara (again, presumably H. nepa or H. zara ). Four females collected by us contained ova: WHT 5930, 367 mm SVL, with 9 ova (14–18.6 × 10.3–11.6 mm), 8 January 1995, from Galle; WHT 5948, 377 mm SVL, with 7 ova (12.2–14.5 × 7.3–9.2 mm) and WHT 5949, 429 mm SVL, with 17 yolks (8.6–12.8 × 5.5–8.8 mm), 19 November 2003 from Maspotha, Kurunegala; and WHT 5844, 325 mm SVL, with 9 yolks (10.1–12 × 6.7–8.4 mm), 28 September 1998, from Malambe, Colombo.

Figures

FIGURE 1. Hypnale hypnale, WHT 5852, male, 311.0 mm SVL: a, b, c, lateral, dorsal and ventral aspects, respectively, of head; d, e, everted left hemipenis, showing (f) enlarged view of a hemipenial lobe; g, dorsal view of paravertebral scale; h, medial view of right palatine of WHT 5857, male, 343.0 mm SVL.

FIGURE 2. Hypnale hypnale, a, distribution in India; b, distribution in Sri Lanka; based on material examined in present study.

FIGURE 3. Hypnale hypnale: a, dosal aspect of neotype, BNHS 2531 - 759, female, 350.0 mm SVL; b, dorso-lateral aspect of a specimen from Galle, Sri Lanka (not preserved); c, reproduction of drawing of H. hypnale in Russell (1801).