Trimeresurus andalasensis, David & Vogel & Vijayakumar & Vidal, 2006

David, Patrick, Vogel, Gernot, Vijayakumar, S. P. & Vidal, Nicolas, 2006, A revision of the Trimeresurus puniceus-complex (Serpentes: Viperidae: Crotalinae) based on morphological and molecular data, Zootaxa 1293 (1), pp. 1-78 : 55-64

Trimeresurus andalasensis spec. nov.

( Figs. 23–28 )

Lachesis puniceus: Holtzinger­Tenever (1917: 443 ; 1919: 89); Sackett (1940: 3).

Trimeresurus puniceus: Matsui et al. (1984: 123) ; Supriatna & Sidik (1996: 241).

Lachesis borneensis (non Atropophis borneensis Peters, 1872 ): Baumann (1913: 273).

Trimeresurus borneensis: David & Vogel (1996: 165 , Fig. 7 ; 200: “ Trimeresurus borneensis ”); De Lang (2003: 27, 29: Fig. 12 ); Gumprecht et al. (2004: 30, 166).

This chresonymy includes only citations based on specimens definitely identified as Trimeresurus andalasensis spec. nov. General references merely citing Trimeresurus puniceus from northern Sumatra without precision are not included.

Holotype. SMF 22429, adult male, from “Nord­Sumatra, Atjeh,Tawar­See, Takengon, 1200 m ü.NN”, Lake Tawar , Takengon, Aceh Province, Sumatra Island, Indonesia, 1200 m asl. Collected by H. R. Roomaaker, 1929.

Paratypes (6 specimens). INDONESIA. Sumatra Island . ANSP 21536 (female), “Blangbeke Dua”, now near Blangkejeren , Aceh Province, 1130 m ; NMBE 1018070 (male) , NMBE 1018071 (female), “ Sumatra, Battak”, now Toba Massif , Sumatera Utara Province ; PSGV 548 (female), Ketembe , Aceh Province ; ZSM 17 /1927, (female), “Gunung Rinsels, Sud. Dehli, Sumatra ”, an unidentified mountain south of Medan, in Toba Massif , Sumatera Utara Province ; ZMB 29641 (female), Padang Highlands, Province of Sumatera Barat .

Diagnosis. A species of the genus Trimeresurus , endemic to Sumatra, characterized by the combination of the following characters: (1) an overall brown coloration, with 17–25 darker crossbands, related to the sex: in males, background colour in various shades of dark greyish­brown with darker irregular dorsolateral blotches, with below, an irregular, elongated blotch of same colour; between the blotches, the background colour is often darker than on the sides of body, with scales heavily powdered with dark producing a confused but not lichen­like pattern; in females, pattern less contrasted but not distinctly paler than in males, in shades of dark yellow­ochre with darker blotches, without the dotted pattern, with broad darker edges and a wide lighter centre, producing a “saddlelike” pattern; males have a more complex pattern, but are not darker than females; (2) a distinctly projected and raised snout, strongly obliquely truncated when seen from the side, subrectangular seen from above; (3) internasals projected, strongly spatulate and bilobate; (4) 19 or more often 21 MSR, smooth or weakly keeled; (5) 1 st supralabial distinct from nasal; (6) 2 nd supralabials bordering the whole of the anterior margin of the loreal pit; (7) 1 to 3 narrow supraoculars, flat or barely convex; (8) a low number of VEN: 144–149 in males and 151–156 in females; (9) occipital and temporal scales smooth or weakly keeled; and (10) IL of the first pair not in contact each with the other.

Etymology. The specific nomen is the Latin genitive noun forged on Andalas, the ancient name of Sumatra.

Suggested English name: Sumatran palm pitviper.

Description of the holotype ( Figs. 20–23 ). Body moderately stout, cylindrical; head distinctly triangular, wide at its base, clearly distinct from the neck, thick and swollen when seen from the side, average, 1.3 times as long as wide and amounting for 7.0 % of SVL. Snout distinctly projected, strongly obliquely trunctated when seen from the side, with a distinct canthus rostralis, rectangular seen from above, with strongly spatulate and bilobated internasal scales, rather long, amounting for 24.4 % of HL or 2.0 times as long as diameter of eye. Eye small, amounting for 0.8 time of the distance eye–lip. Tail long and strongly prehensile.

SVL: 366 mm; TaL: 76 mm; TL: 442 mm; HL: 25.65 mm; ratio TaL/TL: 0.172.

VEN: 144 (+ 2 preventrals); SC: 47, paired, plus one terminal scale; anal shield entire.

DSR: 21—21—15 scales, rhomboid, all nearly entirely smooth.

Rostral not visible from above, about 1.3 times broader than high, triangular; nasals subrectangular, entire; 2 internasals on each side, enlarged, strongly projected, spatulate and strongly bilobate, slightly upturned, separated by 2 small scales; 3/3 canthal scales, slightly larger than adjacent snout scales, bordering the canthus rostralis; 2 elongate subrectangular loreal scales between upper preocular on each side; 2 elongate upper preoculars above the loreal pit; lower preocular forming the lower margin of loreal pit; 2/2 small postoculars; 1 small, narrow, flat supraocular on each side, 2.7 times as long as wide on both sides, 0.5 time as wide as the group of internasals, irregularly bordered on their inner margins by the upper head scales; 5 slightly enlarged scales on upper snout surface on a line between the scales separating the internasals and a line connecting the anterior margins of eyes, smooth, juxtaposed, irregular in shape; 10 cephalic scales on a line between the supraoculars, small, smooth, flat and juxtaposed; occipital scales larger than cephalic scales, smooth; temporal scales small, subequal, in 3 rows, all smooth; one thin, elongated, crescent­like subocular; 9/10 SL; 1 st SL, rather short, separated from nasal; 2 nd SL tall, entirely bordering the anterior margin of the loreal pit, separated from nasal by 2 small scales; 3 rd SL longest and highest, 1.7/1.8 times as long as high, separated from the subocular by 1/1 scale; 4 th SL as long as high, 1.0/0.9 time as low as 3 rd SL, separated from the subocular by 2 scales on each side; 5 th and posterior SL smaller than 4 th one, separated from subocular by 2 scale rows of similar size; 13/12 IL; scales of the 1 st pair not longitudinally in contact, being divided into two scales; first two pairs in contact with anterior chinshields; 8/8 rows of smooth gular scales; throat shields irregularly arranged.

In preservative, the dorsal and lateral body surfaces are nearly uniformly chesnut brown, with very faint darker crossbands. The tail is of same colour than body, weakly mottled with dark brown.

The dorsal head surface is uniformly chesnut brown, paler on the supralabials and behind the head as a very faint postocular streak.

The chin, throat and venter are dark brownish­grey; the chin is barely paler than upper head surface.

Description of the paratypes. A summary of morphological and meristic data of the paratypes is given in Table 10. Other important characters agree with features of the holotype.

Description and variation. Among our sample of 7 specimens, only one male has 19 MSR (NMBE 1018070; from “Mt. Battak”). The other specimen from the same locality (NMBE 1018071) has 21 MSR. Both specimens were described by Baumann (1913) has having 19 MSR. Nevertheless, if NMBE has 19 MSR exactly at midbody, namely at NVE N/2, it has 21 MSR at (NVEN/2) + 2 VEN. The other specimen has indeed 21 DSR, not 19 as stated by Baumann. No other variation correlated to the geographical origin was identified.

The maximal total length known is 809 mm (SVL 698 mm, TaL 111 mm) for a female (PSGV 548). The largest known male is 741 mm long (SVL 621 mm, TaL 120 mm; NMBE 1018070). This species reaches a size similar to Trimeresurus wiroti and Trimeresurus borneensis .

Body relatively slender in males but stout in females. Triangular head elongated, amounting (in adults above SVL 400 mm) for 7.0–7.2 % of SVL (x = 7.1 %) in 2 males, 5.9–6.8 % of SVL (x = 6.5 %) in females, wide at its base, flattened, thick when seen from the side. Snout distinctly projected and more or less raised anteriorly, strongly obliquely trunctated when seen from the side, with a distinct canthus rostralis, rectangular seen from above, with strongly spatulate and bilobated internasal scales; the snout is rather long, amounting (in adults) for 22.3–27.0 % (x = 24.5 %) of HL in both sexes, or 2.2–2.7 (x = 2.5) times as long as diameter of eye without sexual dimorphism. Eye small, amounting for 0.6–0.8 (x = 0.65) times the distance eye–lip in both sexes. Tail tapering progressively and strongly prehensile. Ratio TaL/TL: 0.134 –0.172, with a strong sexual dimorphism (see below).

DSR: 21–27—(19)21—15–17, smooth or weakly keeled in both sexes, smooth on 1 st DSR.

In our samples of 7 specimens, the number of MSR is as follows: 19 (1/7) and 21 (6/7) (see above).

VEN: 144–156 (plus 2 preventrals); SC: 46–50, all paired; anal shield entire.

Rostral not visible from above, about 1.3–1.5 times broader than high, triangular; nasals subrectangular, entire; 2 internasals on each side in all examined specimens, enlarged, strongly projected, spatulate and strongly bilobate, more or less distinctly upturned, flat in 1 specimen; group of internasals separated by 1 (in 2/ 7 specimens) or 2 (in 5/7) small scales; 3–4 canthal scales, larger than adjacent snout scales, bordering the canthus rostralis; 2 elongate loreal scales on each side, subrectangular, between upper preocular and nasal scales; 2 elongated upper preoculars above the loreal pit; lower preocular forming the lower margin of loreal pit; 2 small postoculars in examined specimens; 1–3 small, narrow supraoculars on each side (1: 7/14 occurrences, 2: 2/14, 3: 5/ 14; total number: 2–6; x = 4.0, s = 2.0), flat or convex (1/ 7 specimens), in total 2.4–3.0 (x = 2.7) times as long as wide, 0.4–0.6 (x = 0.5) time as wide as the group of internasals, irregularly bordered on their inner margins by the upper head scales; 5–8 (x = 6.9, s = 0.9) enlarged scales on upper snout surface on a line between the scale separating the internasals and a line connecting the anterior margins of eyes, smooth and juxtaposed (7 in 5/ 7 specimens); 10–13 (x = 11.3, s = 1.0) small cephalic scales on a line between supraoculars (11: 4/ 7 specimens), smooth, flat and juxtaposed; occipital scales larger than cephalic scales, smooth in 4/ 7 specimens or weakly keeled (3/7); temporal scales small, subequal, in 2 or 3 rows, smooth in 6/ 7 specimens, feebly keeled in the other one, without sexual dimorphism; one thin, elongated, crescent­like subocular; 9–12 SL (x = 10.5, s = 1.0) (9: 3/14 occurrences; 10: 3/14; 11: 6/14; 12: 2/14), with most often the combination 11–11 SL); 1 st SL, rather short, separated from nasal; 2 nd SL tall, entirely bordering the anterior margin of the loreal pit, separated from nasal by 2 small scales; 3 rd SL longest and highest, 1.3–1.8 times as long as high (x = 1.5), separated from the subocular by 1 (10/14 occurences) or 2 scales (4/14), without sexual dimorphism; 4 th SL as long as high, 0.8–1.1 (x = 0.9) time as low as 3 rd SL, separated from the subocular by 1 (2/14 occurrences) or usually 2 (12/14) scales on each side, without sexual dimorphism; 5 th and posterior SL smaller than 4 th one, 5 th SL separated from subocular by 2 (in 11/14 occurrences) or 3 (3/ 14) scale rows of similar size, without sexual dimorphism; 12–15 IL (12: 2/14 occurrences; 13: 2/14; 14: 8/14; 15: 2/14); scales of the 1 st pair not longitudinally in contact, being divided into two scales; first two pairs in contact with anterior chinshields; 8–9 rows of smooth gular scales; throat shields irregularly arranged.

In life, the coloration pattern of Trimeresurus andalasensis is very similar to Trimeresurus borneensis . In males, the body background colour is olive­brown, dark greyish­brown or dark yellowish­grey, with about 17–25 large, dorsolateral dark brown, dark reddish­brown, dark purple brown or dark greyish­brown blotches; between the blotches, the background colour is often darker than on the sides of body, with scales heavily powdered with dark grey or dark brown dots or marked with small, irregular, dark blotches; the large dorsolateral blotches are irregular in shape or angulous, reaching down only the 6 th or 7 th DSR, with below an irregular, elongated blotches of same colour separated from the main blotch by a lighter coloration; the centre of the dorsolateral blotches is somewhat lighter and their edge more or less darker; the blotches are usually separated at the level of their upper part; blotches of both sides of body may be either fused or alternate, with all intermediates between perfect opposition and total alternation; on the tips of ventrals and on the 1 st DSR, a series of dark, elongated ventrolateral blotches, more or less irregular. The tail surface is of the same colour than the dorsolateral blotches, with pale greyish­brown or yellowish­brown rings, often edged with cream; the last third or so of the tail is entirely paler reddish­brown or yellowish­brown.

In females, as observed in T. borneensis , the pattern is less complex; the body is dark yellow­ochre, dark greyish­brown or dark greenish­brown, with large, subrectangular, not constricted, dark brown, dark yellowish­brown or dark ochre blotches, in same number than in males; these blotches reach down the 2 nd or 3 rd DSR; they are usually separated one from the other on their sides, with both broad darker edges and a wide lighter centre; blotches of both sides of body may be either fused or alternate, with all intermediates. The tail surface is as described in males, dark brown, chocolate or dark reddish­brown, with pale greyish­brown or reddish­brown rings, the last part being entirely reddish­brown or yellowish­brown. Males can be distinguished from females by their more complex pattern but are not necessarily darker than females.

In both sexes, the dorsal head surface and temporal regions are of the same dark colours as the dorsolateral blotches; in males, the sides of the head and supralabials are often irregularly colored, with light markings on a dark background and scales heavily powdered with dark minute dots; the lower margin of supralabials is marked with cream blotches; in females, the sides of the head are often very dark; a more or less distinct and wide orange­brown, pale reddish­brown or yellowish­ochre postocular streak extending on upper temporals from the eye to the corner of the mouth in widening progressively before vanishing in general body colour; the postocular streak is edged below with a dark streak of same colour than upper head surface, itself sometimes but not necessarily edged with a short area of paler hue below at the limit of the throat and the edge of the supralabials; the postocular streak is indistinct in several examined specimens. Eyes are golden, silvery grey or brownish­grey.

Venter is dark reddish­brown or dark ochre­brown, irregular in colour and mottled with several hues of brown, powdered with numerous minute black dots and small white markings; tips of ventrals with irregular elongated blotches of same colour than dorsolateral blotches intermixed with white blotches, making a very irregular, broken ventrolateral stripe. The chin and throat are paler than upper head surface, with numerous black dots and cream or pale brown irregular markings.

In the sole juvenile that we have observed, a female in preservative, the colour and pattern are basically identical with adult background, more contrasted. The posterior part of the tail is greyish­yellow.

In alcohol, T. andalasensis shows the same pattern of dark brown, dark greyish­brown or dark yellow­ochre on a lighter background, producing the patterns described above, often rather darkened. Females tend to be much darker than males, with a more subdued pattern, whereas it remains more complex with irregular hues in males.

Comparison with other species. Trimeresurus andalasensis spec. nov. belongs to the Trimeresurus borneensis ­group and differs from T. puniceus and T. cf. puniceus by the general characters given above to separate these groups.

T. andalasensis differs from other species of the Trimeresurus borneensis ­group by characters given in Tables 7–8. From T. wiroti , T. andalasensis differs by the combination of the following characters: (1) a lower number of ventrals in T. andalasensis than in T. wiroti , without overlapping); in males: 141–149 (x = 146.5, s = 3.5) vs. 159–167 (x = 163.0, s = 2.4); in females: 151–156 (x = 154.0, s = 2.3) vs. 158–167 (x = 161.0, s = 2.9); (2) a lower total number of supraoculars in T. andalasensis , 2–6 (x = 4.0, s = 2.0) vs. 4–8 (x = 5.3, s = 1.3) in T. wiroti , although this difference is not significant when tested by Mann­ Whitney’s test; (3) the shape of supraocular scales, flat or convex in T. andalasensis , often raised in T. wiroti ; and (4) occipital and temporal scales smooth or weakly keeled in T. andalasensis , usually distinctly keeled in T. wiroti .

T. andalasensis is morphologically very close to T. borneensis . These species differ mostly by the combination of the following characters: (1) ratio TaL/TL in males, 0.162 –0.172 (x = 0.167, n = 2) in andalasensis vs. 0.165 –0.189 (x = 0.173, n = 13) in borneensis (U = 5, P <0.05); (2) a distinctly lower number of VEN in males, 144–149 (x = 146.5, n = 2) in T. andalasensis vs. 154–166 (x = 160.3, n = 13) in T. borneensis ; (3) occipital and temporal scales smooth or weakly keeled in T. andalasensis , usually distinctly keeled in T. borneensis ; and (4) a proportionnally smaller eye in T. andalasensis , expressed as the ratio ED/DEL: in males: 0.60–0.75 (x = 0.68, n = 2) in T. andalasensis vs. 0.80–1.00 (x = 0.91, n = 13) in T. borneensis ; in females: 0.60–0.65 (x = 0.61, n = 4) in T. andalasensis vs. 0.65–0.80 in T. borneensis (x = 0.70, n = 18). As explained below, T. andalasensis is also separated from T. borneensis at the species level also due to biogeographic considerations and to the species concept followed in this paper.

Lastly, T. andalasensis is distinguished from T. brongersmai by the following combination of characters: (1) a larger size in T. andalasensis , with a TL max of 809 mm vs. 441 mm in T. brongersmai ; (2) the number of MSR, usually 21 MSR (1 specimen with 19 MSR) in T. andalasensis (x = 20.7, s = 0.8) vs. 19–21 (x = 19.6, s = 0.9) in T. brongersmai (U = 1.5, P <0.05); (3) the shape of supraoculars, strongly erect, directed upwards and outwards in T. brongersmai , mostly flat in T. andalasensis ; (4) higher numbers of ventral and subcaudal scales in females of T. andalasensis than in females of T. brongersmai , without overlap (see Table 7); (5) a higher number of Cep in T. brongersmai (11–15; x = 13.0, s = 1.3) than in T. andalasensis (10–13; x = 11.3, s = 1.0) (see Table 8; U = 10, P <0.05); and (6) occipital and temporal scales smooth or weakly keeled in T. andalasensis , strongly keeled in T. brongersmai .

Sexual dimorphism. It is significant in the relative length of the tail, in the number of subcaudals, and in the pattern:

(1) Strong difference in the ratio TaL/TL:

males: 0.162 –0.172 (x = 0.167, s = 0.007); females: 0.137 –0.149 (x = 0.143, s = 0.007)

(2) Differences in the number of ventrals:

144–149 (x = 146.5, s = 3.5) in males vs. 151–156 (x = 154.0, s = 2.3) in females.

(3) Difference in the pattern. In preservative, the pattern of males is more contrasted and complex than in females.

Hemipenes. Hemipenes of this species have not been examined.

Range ( Fig. 4 ). INDONESIA. Sumatra Island . Province of Aceh. Known from Blangkejeren, Gunung Leuser National Park , Ketembe, Takengon; Province of Sumatera Utara. Recorded from Toba Massif; Province of Sumatera Barat. Recorded from Gunung Gadut and “Padang Highlands”. This species is endemic to the mountainous areas of northern and western parts of the island.

Specimens recorded by Matsui et al. (1984) from Mt. Gadut, Sumatera Barat Province, are here referred to as Trimeresurus andalasensis spec. nov. on the basis of scale counts provided by these authors.

Biology. Little has been recorded on the biology of this species. Matsui et al. (1984) obtained their two specimens around 500 m asl, whereas Baumann (1913) recorded one animal at an elevation of 1000 m. The specimen ANSP 21536, reported by Sackett (1940), was found at an elevation of 1130 m. Trimeresurus andalasensis is likely to be a typical inhabitant of wet montane forest.

Comments. Trimeresurus andalasensis has been depicted alive in David & Vogel (1996: 200, as “ Trimeresurus borneensis ”), De Lang (2003: 28: Fig. 12 ) and Gumprecht et al. (2004: 166: Figs. I–V). Ink drawings of the head (specimen ZMB 29641) appeared in David & Vogel (1996: 161: Fig. 6 ).

Figures

FIGURE 4. Map: distribution of the taxa recognized in the Trimeresurus puniceus­complex. Symbols: dots: Trimeresurus puniceus.—Squares: Trimeresurus cf. puniceus.—Triangles: Trimeresurus borneensis.—Inverted triangles: Trimeresurus wiroti.—Pentagons: Trimeresurus andalasensis.—Stars: Trimeresurus brongersmai.

FIGURE 6. Trimeresurus puniceus. Syntype, RMNH 1557. Lateral view of head. Photograph by Roger Bour.

FIGURE 7. Trimeresurus puniceus. Living male, from Java. Photograph by Rick Hodges.

FIGURE 12. Trimeresurus cf. puniceus. Specimen from Anamba Island (USNM 26544). General view. Photograph by Gernot Vogel.

FIGURE 20. Trimeresurus wiroti. Living male, from South Thailand. Photograph by Gernot Vogel.

FIGURE 21. Trimeresurus wiroti. Living female, from South Thailand. Photograph by Gernot Vogel.

FIGURE 22. Trimeresurus wiroti. Hemipenes. Photograph by Lawan Chanhome.

FIGURE 23. Trimeresurus andalasensis. Holotype, SMF 22429. General view. Photograph by Gernot Vogel.

FIGURE 24. Trimeresurus andalasensis. Holotype, SMF 22429. Left side of the head. Photograph by Gernot Vogel.

FIGURE 25. Trimeresurus andalasensis. Holotype, SMF 22429. Top of the head. Photograph by Gernot Vogel.

FIGURE 26. Trimeresurus andalasensis. Holotype, SMF 22429. Venter. Photograph by Gernot Vogel.

FIGURE 27. Trimeresurus andalasensis. Specimen ZMB 29641. Right side of the head. Drawing by Petr Kliment

FIGURE 28. Trimeresurus andalasensis. Female from Aceh, Sumatra. Photograph by Ludwig Trutnau.