Trimeresurus brongersmai Hoge, 1969

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 : 64-70

Trimeresurus brongersmai Hoge, 1969

( Figs. 29–31 )

Trimeresurus brongersmai Hoge, 1969: 459 . Type locality. “Lugu, Simalur, Sumatra ”, now Lugu , Simeuleue Island, Aceh Province, Indonesia. Holotype. RMNH 5654 A, adult male. Collected by E. Jacobson, April 1913.

Material (8 specimens). INDONESIA. Siberut Island. BMNH 1979.262 – 265 (4 females), no precise locality .— Simeuleue Island. RMNH 5181 (female), ZMA 13120 (female), Sinabang ; RMNH 5649 (male), Sibogo ; RMNH 5654 A (male; holotype), Lugu .

Diagnosis. A species of the genus Trimeresurus , endemic to islands off the west coast of Sumatra Island, characterized by the combination of the following characters: (1) in both sexes, an overall brown coloration, with 25–30 darker crossbands, made of a dark

background colour in various shades of dark greyish­brown, with short, irregular, elongated darker dorsolateral blotches, lighter in their centre and darker on their edges, with below a smaller subrectangular or subtriangular dark greyish­brown blotche of same colour; between the blotches, the background colour is heavily spotted with dark dots; a row of large, subrectangular blotches on the ventral tips and 1 st –2 nd DSR, with cream blotches in between; (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, laterally expanded; (4) 19 or 21 MSR, distinctly keeled; (5) 1 st supralabial distinct from nasal; (6) 2 nd supralabials bordering the whole of the anterior margin of the loreal pit; (7) 4 or 5 narrow supraoculars, strongly erect and divergent; (8) a low number of VEN: 148–149 in males and 129–142 in females; (9) occipital and temporal scales strongly keeled; (10) IL of the first pair not in contact each with the other; and (11) hemipenes short, massive and spiny.

Description and variation. Among our sample of 8 specimens, there is a geographically related difference in the number of MSR. From Simeulue Island (type locality), the six known specimens all have 19 MSR ( Hoge & Romano, 1974; examined specimens), whereas, in four specimens from Siberut Island, only one specimen has 19 MSR, one has 20 and two have 21 MSR. As no other variation correlated to the geographical origin was identified, we regard this variation in the number of dorsal scale rows has falling into normal intraspecific variation.

The maximal confirmed total length known is 441 mm (SVL 378 mm, TaL 63 mm) for a female (BMNH 1979.263). The longest male is 406 mm long (SVL 341 mm, TaL 65 mm; RMNH 5654A).

Body quite slender in males and in females. Triangular head elongated, average, amounting (in adults above SVL 300 mm) for 6.1–6.6 % of SVL (x = 6.4 %) in males, 7.1–7.4 % of SVL (x = 7.3 %) in females, wide at its base, flattened, thin in males, thick in females when seen from the side. Snout distinctly projected and raised anteriorly, strongly obliquely trunctated when seen from the side, with a distinct canthus rostralis, flattened and rectangular when seen from above with strongly spatulate and bilobated internasal scales; the snout is rather long, amounting (in adults) for 25.7–27.1 % (x = 26.4%) of HL in males and 27.5–29.5 % (x = 28.1 %) of HL in females, or 1.7–1.8 (x = 1.8) times in males and 2.0–2.4 (x = 2.2) times as long as diameter of eye. Eye large, amounting for 1.0 time in males and 0.8–1.0 (x = 0.9) times in females of the distance eye–lip. Tail average, tapering progressively and strongly prehensile. Ratio TaL/TL: 0.143 –0.160, with a sexual dimorphism (see below).

DSR: 21–25—19–21—15–17, distinctly keeled in both sexes, smooth on 1 st DSR.

In our samples of 8 specimens, the number of MSR is as follows: 19 (5/8), 20 (1/8) and 21 (2/8) (see above).

VEN: 137–149 (plus 2 preventrals); SC: 39–49, all paired; anal shield entire.

Rostral not visible from above, about 1.4–1.6 times broader than high, triangular; nasals subrectangular, entire, the anterior part bent forward; usually 2 (10/16 occurrences) or 1 (6/16) internasals on each side, enlarged, strongly projected, spatulate and strongly bilobate, raised and distinctly upturned; internasals or group of internasals separated by 1 (in 4/ 8 specimens), 2 (in 3/8) or 3 (1/8) small scales; 4–5 canthal scales, slightly larger than adjacent snout scales, bordering the canthus rostralis; 2 elongate loreal scales, subrectangular, between upper preocular and nasal scales in all examined specimens; two elongated upper preoculars above the loreal pit; lower preocular forming the lower margin of loreal pit; 2 small postoculars; 4–5 small, narrow supraoculars on each side (4: 12/16 occurrences, 5: 4/16; total number: 8–9; x = 8.5, s = 0.5), spiny­like, erected and divergent, extending out of the margin of the head, in total 2.1–2.4 (x = 2.2, s = 0.1) 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; 8–9 (x = 8.4, s = 0.5) slightly 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, juxtaposed, irregular in shape (8 in 5/8 and 9 in 3/ 8 specimens); 11–15 (x = 13.0, s = 1.3) cephalic scales on a line between supraoculars (11: 1/8; 12: 2/8; 13: 2/8; 14: 2/8; 15: 1/ 8 specimens), small, smooth, flat and juxtaposed; occipital scales larger than cephalic scales, strongly keeled in both males and females; temporal scales small, subequal, in 2 or 3 rows, strongly keeled in both sexes; one thin, elongated, crescent­like subocular; 9–11 SL (x = 10.0, s = 0.5) (9: 2/16 occurrences; 10: 12/16; 11: 2/16); 1 st SL, rather short, always separated from nasal; 2 nd SL tall, entirely bordering the anterior margin of the loreal pit, separated from nasal usually by 2 or 3 small scales; 3 rd SL longest and highest, 1.2–1.4 times as long as high (x = 1.3), separated from the subocular by usually 1 (12/16 occurences) or 2 (4/16) scales, without clear sexual dimorphism; 4 th SL as long as high, 0.7–0.9 (x = 0.8) time as low as 3 rd SL, separated from the subocular by 2 (14/16 occurrences) or 3 (2/16) scales on each side; 5 th and posterior SL smaller than 4 th one, 5 th SL separated from subocular by 2 (in 14/16 occurrences) or 3 (2/ 16) scale rows of similar size; 10–13 IL (10: 1/16 occurrences; 11: 8/16; 12: 4/16; 13: 3/ 16); scales of the 1 st pair not longitudinally in contact, being divided into two scales; first two pairs in contact with anterior chinshields; 7–8 rows of smooth gular scales; throat shields irregularly arranged.

In preservative, the body is dark grey or dark brownish­grey, with about 25–30 rectangular, elongated but short, dark greyish­brown or blackish­brown dorsal blotches extending downwards on 7 th DSR; the blotches are more or less longitudinally divided at the level of the vertebral line, the two haves being either fused or alternated; on each side of body, a series of elongated subrectangular or subtriangular dark greyish­brown blotches just below the dorsal blotches, becoming fused together in the rear part of the body. Scales between the dorsal blotches and scale rows below the lateral blotches heavily spotted with dark dots; a row of large, subrectangular blotches on the ventral tips and 1 st ­2 nd DSR, with cream blotches in between. The tail surface is basically the same colour as the dorsum, with 10–12 dorsal blotches, becoming pale yellowish­brown near its tip.

The dorsal head surface and temporal regions are of the same dark colour as the dorsolateral blotches; in males, the sides of the head and supralabials are irregularly colored, with a mottled pattern of light markings on a dark background and scales heavily powdered with dark minute dots; the lower margin of supralabials is much lighter or cream; in females, the sides of the head are more uniform and heavily powdered with minute black dots; in males, a distinct, more or less wide pale grey or pale yellowish­grey postocular streak extending on upper temporals from the eye to the corner of the mouth in widening progressively before vanishing in general body colour; postocular streak less distinct in females; 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.

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

In juveniles, the colour and pattern are basically identical, somewhat more contrasted but not lighter than in adults. We have not examined living specimens. The posterior part of the tail is yellowish­grey.

The colour in life has been recorded on a single specimen (Vogel, 2006). Its pattern and coloration do not differ from description given above.

Sexual dimorphism. It is strongly marked in the relative length of the tail, in the number of ventrals and in the pattern:

(1) Difference in the ratio TaL/TL:

males: 0.166 –0.189 (x = 0.173, s = 0.007); females: 0.141 –0.149 (x = 0.143, s = 0.003)

(2) Difference in the average numbers of subcaudals:

48–49 (x = 48.5, s = 0.7) in males vs. 39–44 (x = 42.5, s = 2.0) in females.

(3) Difference in the pattern: the fames are somewhat darker than the males.

in females.

Hemipenes. The everted hemipenes have not been described. In situ, they are short and massive, extending up to 9 th SC and forked opposite the 4 th SC, smooth at is base, spinous from forking point up to the tip.

Comparison with other species. Trimeresurus brongersmai 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.

Trimeresurus brongersmai differs from the three other species of the Trimeresurus borneensis ­group by (1) its erected, divergent and more numerous supraocular scales and (2) the usually lower number of MSR, 19 vs. 21. From T. borneensis , T. brongersmai differs furthermore by (1) a lower ratio TaL/TL in males, and (2) lower number of ventral scales in males and females (see Table 7). Additional differences between T. brongersmai and T. wiroti and T. andalasensis appear in the respective accounts of these latter species and in Tables 7–8.

Range ( Fig. 4 ). INDONESIA. This species is currently known from two islands off the west coast of Sumatra. Simeuleue Island (Aceh Province). Known from three localities (see Hoge & Romano, 1974 and specimens listed above).— Siberut Island (Sumatera Utara Province). Cited from this large island without precise locality ( Dring et al., 1990; examined specimens).

Trimeresurus brongersmai should be searched for in other islands off western Sumatra, especially Nias and Batu islands. At the southern tip of the Mentawai Archipelago, Trimeresurus cf. puniceus has been recorded in Pulau Pagai Utara (North Pagai Island).

Biology. There is virtually no available data on the ecology of Trimeresurus brongersmai . This species is probably a forest dweller. Trimeresurus brongersmai is ovoviviparous. Specimen RMNH 5181 contains an unfertilized egg and three nearly fully developped embryos, the longest one being about 130 mm long.

The first specimen ever recorded of Trimeresurus brongersmai seems is RMNH 5654A, obtained in April 1913, and mentionned, as Lachesis puniceus , by De Rooij (1922).

Comments. Trimeresurus brongersmai has not yet been depicted alive to our best knowledge. Photographs of the preserved holotype may be found in Gumprecht et al. (2004: 167: Figs. I–VI). Ink drawings of the head and body appeared in Hoge & Romano (1974: 154: Figs. 1–3 ).

Figures

FIGURE 1. Plot of first two principal canonical variables of the Principal Component Analysis on males of the Trimeresurus puniceus complex. The first two components explained 57.9 % of the variance. Six clusters are identified.

FIGURE 2. Plot of first two principal canonical variables of the Principal Component Analysis on females of the Trimeresurus puniceus complex. The first two components explained 56.9 % of the variance. Six clusters are identified.

FIGURE 3. ML tree. Starting tree: stepwise addition, TBR branch swapping with 100 random addition replications, log­likelihood, ­1629.05155) Values above branches are ME/MP/ML bootstrap values. All Bayesian posterior probabilities are 100%.

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 29. Trimeresurus brongersmai. Holotype, RMNH 5654A. General view. Photograph by Roger Bour.

FIGURE 30. Trimeresurus brongersmai. Holotype, RMNH 5654A. Left side of the head. Photograph by Roger Bour.

FIGURE 31. Trimeresurus brongersmai. Paratype, RMNH 5649. General view. Photograph by Roger Bour.