Cryptelytrops rubeus, Malhotra & Thorpe & Stuart, 2011

Malhotra, Anita, Thorpe, Roger S. & Stuart, Bryan L., 2011, Two new species of pitviper of the genus Cryptelytrops Cope 1860 (Squamata: Viperidae: Crotalinae) from Southeast Asia, Zootaxa 2757 (1), pp. 1-23 : 9-15

Cryptelytrops rubeus sp. nov. (Ruby-eyed Green Pitviper)

Fig. 5 , 6 ; Tables 1–3

Trimeresurus macrops Kramer 1977 : Kramer (1977): 757 (part); Regenass and Kramer (1981): 184 (part); Orlov et al. (2002a): 193 (part); Orlov et al. (2002b): 353 (part); Stuart et al. (2006a): 152.

Trimeresurus cf. macrops Kramer 1977 : Gumprecht et al. (2004): 236.

Material examined. Cambodia, Mondolkiri Province, Seima Biodiversity Conservation Area, FMNH 262717 – 21. Vietnam, southern part of country (no precise locality), BMNH 2005.1602. Vietnam, Ho Chi Minh City, NMBA 12461. Vietnam, Cu Chi and Bien Hoa, AFS98.53 – 55.

Holotype. FMNH 262718, adult female, collected at 1820 hrs on an herbaceous plant 1 m from the O Kamen Stream in hilly evergreen forest, Seima Biodiversity Conservation Area (formerly part of Samling Logging Concession), O’Rang District, Mondolkiri Province, Cambodia (12.326 N, 107. 092 E), 500 m elevation, on 1 November 2003 by BLS, K. Sok, and T. Neang.

Paratypes. FMNH 262717, 262719 – 262721 (all males, collected from near the type locality in hilly evergreen forest between 450 – 500 m elevation, near streams between 1 – 6 November 2003); FMNH 259190 (female, Phnom Nam Lyr Wildlife Sanctuary , Mondolkiri Province, Cambodia) ; BMNH 2005.1602 (female, from an unknown location in southern Vietnam) ; NMBA 12461 (Saigon, southern Vietnam) .

Additional material. Data for s everal specimens obtained from dealers in the vicinity of Ho Chi Minh City, southern Vietnam are included in all analyses. The specimens were stated to originate from Cu Chi (10.75 N, 106.67 E) and Bien Hoa (10.95 N, 106.82 E). These specimens were left in the care of Dr T-X. Kiem (Cho – Ray Hospital, Vietnam) .

Diagnosis. Cryptelytrops rubeus is distinguished from all other Asian pitviper species which have the typical "green pitviper" colouration (uniform green dorsal colour and a lateral stripe present on the first few dorsal scale rows in one or both sexes), except other species of Cryptelytrops , by the presence of a fused first supralabial and nasal scale. It can be distinguished from C. albolabris , C. insularis and C. septentrionalis primarily by the larger size of the eye (most obvious in adults), the wider supraoculars, and the shape of the head. The latter is more elongate – oval in C. albolabris , C. insularis and C. septentrionalis , but widens quite abruptly behind the eyes in C. cardamomensis , C. macrops s.s. and C. rubeus to give the latter a characteristically triangular shaped head. Cryptelytrops rubeus can be distinguished from C. cardamomensis sp.nov. (described above) using the combination of the following characters (further details are given in Table 2 ). In males, C. rubeus tends to have fewer scales between the rear edges of the supraoculars (BTWSUPOC2), a relatively smaller eye (DEYE), and a less prominent postocular white stripe (SCROC). The scale reduction from 19 to 17 dorsal scale rows (DV19TO17) tends to involve lower scale rows, it tends to have less keeled body scales at mid-body (BSCK), and fewer scales between the last supralabial and the chin shields (VENTEDGE). In females, the scale reduction from 19 to 17 dorsal scale rows (DV19TO17) tends to involve higher scale rows in C. rubeus than in C. cardamomensis , it has a relatively shorter head (LHEAD), a small scale is never present between the nasal scale and the scale bordering the anterior edge of the pit (NASPIT), the lateral white stripe covers a larger proportion of the first dorsal scale row (SCR1), it tends to have fewer (larger) scales bordering the supralabial scales (BORSUPOC), and less keeled body scales at mid-body (BSCK). The scale reduction from 12 to 10 scale rows around the tail (SC12O10) also tends to occur closer to the vent in females of C. cardamomensis than C. rubeus and they also have relatively smaller eyes (DEYE).

Compared to C. macrops s.s ( Table 3 ), in both sexes C. rubeus has a more prominent lateral stripe with the white area covering a larger proportion of the first scale row (SCR1), less keeled body scales at mid-body (BSCK), and the scale reduction from 19 to 17 dorsal scale rows (VS19TO17) occurs further away from the head. In addition, there are never any small scales present between the nasal scale and the scale bordering the anterior edge of the pit (NASPIT) in C. rubeus , while they sometimes occur in C. macrops s.s. In addition, males tend to have a less prominent postocular stripe (SCROC), fewer sublabial scales (SUBLAB), fewer scales between the rear edges of the supraocular scales (BTWSUPOC2), fewer scales between the last supralabial and the chin shields (VENTEDGE), and less keeled temporal scales (KTEMP). In females, C. rubeus tends to have fewer ventral scales, fewer (larger) scales bordering the supraoculars (BORSUPOC), and a larger number of scales between the rear edges of the supraoculars (BTWSUPOC2) than C. macrops s.s.

Description of holotype. Body cylindrical; head triangular in dorsal aspect, very distinct from neck. Canthus rostralis distinct. Head scales small (no large dorsal shields), smooth except for weakly keeled scales in temporal region, region above suprabials, and rear of head. Dorsal body scales weakly keeled. 163 ventral scales, 58 pairs subcaudal scales, 21 dorsal scales at mid – body. Rostral scale roughly triangular, upper edge about half width of lower edge. Pupil vertically elliptical. Loreal pit present. Nostril completely enclosed in nasal scale. Nasal scale partially fused with first supralabial, suture extending part way towards nostril on both sides. Eleven and 12 supralabials on right and left sides respectively, 12 sublabials, two postocular scales. Shield bordering anterior edge of pit fused with second supralabial, lacking any small scales between it and nasal. Subocular scale separated by one scale from third, fourth, and fifth supralabials. At least 8 scales between supraoculars, 14 scales between their posterior edges. Five teeth on palatine, 16 on pterygoid, and 16 on dentary. Snout – vent length 49.9 cm; tail length 9.1 cm. Head length measured from tip of snout to posterior edge of lower jawbone 24.9 mm; head width measured between rear outer edges of supraoculars 11.4 mm, at widest point of head 16.85 mm. Supraocular scale (on right hand side) 5.7 mm long, 2.05 mm wide. Distance from eye to nostril 5.0 mm, eye to pit 1.0 mm, posterior edge of pit to anterior edge of nostril 4.85 mm. Eye diameter 4.0 mm. Scale reduction formula:

Colour of holotype in preservative. Dark brownish grey on dorsal surface of head, fading to steely blue grey laterally. Ventral scales are very similar in colour to the first few dorsal scale rows. Pale lateral stripe present, covering approximately one – quarter of first scale row at mid-body, fading towards the head. Upper and lower labials not distinct in colour from rest of head. Paired chin shields, scales between the chin shields creamy white in colour, although a single pair of chinshields and the occasional scale blue – grey. Ventral scales uniformly blue – grey.

Colour in life. Photographs of a red – eyed green pitviper which is almost certainly referable to C. rubeus , taken in Nam Cat Tien National Park in May 2000, were supplied by P-P. van Dijk. This specimen, together with those pictured in Gumprecht et al. (2004) (p. 236 – 238), photographs taken by AM of the specimens from Cu Chi and Bien Hoa above, of FMNH 262717 by BLS in Cambodia (described in Stuart et al. [2006a), and of BMNH 2005.1602, provided by K. Udomritthiruj ( Fig. 6 ), were used to write this description of the colour of the species in life.

Posterior half of the body dark to grass green, similar on ventral and dorsal surface. Lateral white stripe more prominent and may extend onto the second dorsal scale row in males (confined to first row in females). In males, lateral white stripe may be edged below with dull reddish–brown more obvious on the rear half of the body. White stripe may also extend onto head as postocular stripe, passing underneath the eye and fading out on lower preocular scale. Upper lip (supralabials and 1–2 scale rows above) suffused with pale blue and differentiated from rest of head; mostly confined to scale edges, but may be more widespread towards rear of mouth. Pale blue also largely covering sublabials, genials and paired chinshields, extending onto central part of the ventral scales in anterior of body. Scales between the chinshields and the sublabials creamy white. Patches of other colours including deep yellow also present on these scales. Interstitial skin black. Tail solid orange–red, this extending to vent dorsally and ventrally (although in males forming distinct pattern of blotches on the distal half of the tail). Eye bright or deep reddish–orange in both sexes.

Variation. Sexual dimorphism is not very obvious although females lack postocular stripes and have a less prominent lateral stripe, never edged with brick red. Eye colour appears to be the same in both sexes, with the exception of one female from southern Vietnam (BMNH 2005.1602), in which the eye was golden yellow. Females have relatively shorter tails and fewer subcaudals (52 – 63, versus 63 – 74 in males). Sexual dimorphism in size may also be low/absent in this species (maximum recorded 50.3 cm SVL versus 50.5 cm for males), but the sample is small. The number of ventral scales is similar in both sexes (159 and 172). Body scales smooth to strongly keeled at mid – body. Temporal scales show weak to strong tubercular keeling, and keeling is also weak to strongly present on the scales covering the rear of the head. In some specimens, the scales in the region between the temporal scales and supralabials are also keeled. The ratio between the lengths of the upper and lower edges of the rostral scale varies between 0.39 and 0.53. Supralabials vary between 8 and 12 and sublabials between 9 and 13. The suture that partially separates the first supralabial and nasal scale is more obliquely inclined than in the other species, where it tends to be more horizontal, and tends to be confined to the rear of the nostril. The minimum number of scales between supraoculars varies between 7 and 12 and there are 7 and 19 scales between the posterior edges of the supraoculars. There are never any small scales between the nasals and shield bordering the anterior of the pit, and exceptionally there was a single scale between the internasals in one specimen. There are 0 – 1 scales between the third and fourth supralabials and the subocular, and 1 – 2 scales between the fifth supralabial and the subocular scale. Hemipenes do not differ notably from those of C. macrops s.s. There are always five teeth on the palatine bone (as in most other pitvipers of the Trimeresurus radiation), while those on the pterygoid vary between and 15 – 18 (in one specimen, a count of 12 was made on one side, but the other side had 16, a count that was within the range seen in other specimens), and on the dentary between 14 – 17.

Distribution. Cryptelytrops rubeus is currently known from southern Vietnam from the vicinity of Ho Chi Minh City and the low-elevation hills on the southern and western edges of the Langbian (= Dalat) Plateau in southern Vietnam and eastern Cambodia ( Fig. 1 ). The occurrence of this species in Nam Cat Tien National Park is supported by a photographic record of a red–eyed green pitviper ( Fig. 6 ), which is almost certainly referable to C. rubeus .

Ecology. Specimens from Cambodia were collected at night (1810 – 2040 h) on the soil bank, herbaceous plants, bushes, tree roots, and tree branches. All were found within 10 m of swift, rocky streams (often near waterfalls) at an elevation of 450 – 500 m. The species was found in sympatry with Viridovipera vogeli at this location. FMNH 262720 contained mammal hairs in its hind gut (stomach contents were too digested to allow more accurate identification of prey). The specimen in Nam Cat Tien was found near a small temporary pond, c. 1 km northeast of the park headquarters. It was first noted at 2050 hrs moving on grass adjacent to the pond towards tangled poolside vegetation, and later found at 2230 hrs coiled in bamboo/shrubby undergrowth a few meters away.

Etymology. Rubeus, from Latin, meaning reddish, refers to the reddish eye colouration in both sexes, the presence of at least a partial red lateral stripe in males, and the bright and prominent red coloration on the tail, which differentiates it from other macrops group species.

Figures

FIGURE 1. Map of Southeast Asia, showing the distribution of the two new species and Cryptelytrops macrops s.s. Symbols indicate sampling localities used in the genetic analysis to define species. Grey circles: C. macrops s.s; open diamonds: C. cardamomensis sp. nov.; black triangles: C. rubeus sp. nov. The empty circle and triangle denotes localities of specimens that have either been referred to the corresponding species on the basis of photographs, or for which the locality is uncertain and requires confirmation.

FIGURE 5. Line drawings of the head scalation of the holotype of Cryptelytrops rubeus sp. nov. (FMNH 262718). Labelling as in Fig. 3 (a: 4.00mm, b: 2.05mm, c: 3.45mm, d: 24.9mm).

FIGURE 6. Cryptelytrops rubeus sp.nov. A. Close-up of head of male (left) and female (right) from vicinity of Ho Chi Minh city, South Vietnam (photos: A Malhotra); B. Close-up of head of male (left) and female (right) from South Vietnam; C. Closeup of tail of male from B; D. Pair from B (male above) (photos: K Udomritthiruj).

Tables

TABLE 3. Mean and standard deviations of morphological characters that in combination can be used to distinguish C. macrops s.s. and C. rubeus sp. nov. Data are for the maximum number of specimens available for that character. Cm = C. macrops s.s., Cr = C. rubeus. Character abbreviations are explained in Appendix 1.

Character	Cm	Cr
a. Males
SCROC	0.69 (±0.93)	0.33 (±0.82)
SCR1	0.19 (±0.19)	0.32 (±0.08)
BSCK	0.8 (±0.25)	0.38 (±0.21)
VS19TO17	68.00 (±1.99)	69.29 (±1.53)
SUPLAB	9.65 (±0.49)	9.58 (± 1.02)
SUBLAB	11.62 (±0.54)	10.92 (±0.74)
BTWSUPOC2	11.96 (±1.22)	10.17 (±1.94)