Cryptelytrops honsonensis, Grismer, Lee, Tri, Ngo Van & Grismer, Jesse L., 2008

Grismer, Lee, Tri, Ngo Van & Grismer, Jesse L., 2008, A new species of insular pitviper of the genus Cryptelytrops (Squamata: Viperidae) from southern Vietnam, Zootaxa 1715, pp. 57-68 : 61-66

Cryptelytrops honsonensis sp. nov.

Fig. 2 , Tables 1, 2

Holotype. UNS 0 353, adult female ( Fig. 2 ) from Hon Son island in the Kien Hai District of the Kien Giang Province, Vietnam. It was collected at 09° 47’ 95.2” N, 104° 37’ 85.6” E at 100 m a.s.l. by Ngo Van Tri on 29 July 2007.

Paratypes. UNS 0 354 (adult male) and UNS 0 355 (adult female) collected at the same locality as the holotype by Ngo Van Tri on 24 March 2006 and 4 August 2006, respectively.

Diagnosis. Cryptelytrops honsonensis differs from all other species of Cryptelytrops by the combination of having dark body bands; lacking a ventrolateral stripe and a red or reddish-brown tail; having a dull-yellow to brown ground color as opposed to being green; females having a maximum SVL of 557 mm and a SVL of 523 mm in the single male; females having a TaL/SVL ratio of 0.15–0.16 and a ratio of 0.23 in the single male; 21 dorsal scale rows at midbody; 183–186 ventral scales in females and 186 in the male; 54–58 subcaudal scales in females and 74 in the male; 10 or 11 supralabials and 12 infralabials; 9–12 scales across the top of the head; smooth occipital and temporal scales; internasals in contact; and the third and fourth supralabials not contacting the subocular scale. Table 2 summarizes the states of these characters across all 13 species of Cryptelytrops .

Description of holotype. Adult female; body long and thin (Ti = 0.02); head triangular, stout and pointed; distance between nostrils 4.3 mm, DBN/HL 0.17; distance between pits 6.6 mm, DBP/HL 0.26; head length 25.7 mm; head width 19.4 mm; HW/HL 0.75; head 13.4 mm wider than neck; SVL 557 mm; Tal 91 mm; Tal/ SVL 0.16; dorsal scale rows 25-21-15; one tripartate preventral scale; 186 ventral scales; 58 paired subcaudal scales; lower five rows of dorsal body scales smooth, medial rows weakly keeled; all dorsal caudal scales smooth; anal plate undivided.

Rostral narrow and rounded, base flared, followed posteriorly by a small, circular, azygous scale; azygous scale bordered laterally by an internasal, followed posteriorly by small, round, subimbricate, smooth head scales; internasals rectangular, twice as wide as deep, bordered anteriorly and anteroventrally by nasal, bordered posterolaterally by a small, round scale; two large, moderately sharp, triangularly shaped canthals between nasal scale and anterior border of eye; posterior canthal in contact with anteroventral margin of supraocular; supraocular 2.51 times longer than wide (LSupOc/WSupOc 2.51), surrounded by 11 (L) 8 (R) head scales, medial margins of supraoculars smooth; 11 head scales in a line between midsection of supraoculars; 33 head scales across the top of the head along a line from rostral scale to limit of neck; naris visible in lateral view; rostral bordered laterally by nasal; nasal bordered ventrally by first supralabial and fused to it anteriorly; supralabials 10 (L and R); infralabials 12 (L and R); nasal bordered posteriorly by small, vestigial loreal on right (absent on left); second supralabial crescent shaped, twice as high as wide; upper margin of lower preocular and lower margin of upper preocular converge posteriorly to form the upper, lower, and pointed posterior borders of the triangularly shaped facial pit opening; upper and lower preocular bordered posteriorly by eye; 11 (R) 10 (L) scales surround eye including preoculars and subocular; eye bordered ventrally by long, crescent shaped subocular and followed posteriorly by five small, round postoculars; mental triangular, equally high as wide, followed posterolaterally by first infralabials which contact on midline; first infralabials followed posteriorly by two large chinshields meeting on midline, followed in turn by four smaller (one-half the size) chinshields on right and five on left, all contacting along midline; no enlarged sublabial scales.

Color in life ( Fig. 2 ). The head is brown, heavily suffused with irregularly shaped, darker markings. The iris is orange centrally and brown peripherally. There is no ventrolateral striping. The lores are slightly lighter than the head and postorbital stripes are absent. The ground color of the body is straw-yellow with approximately 92 zig-zagged, irregular, dark-brown, body bands. Reddish-brown markings occur ventrolaterally which show varying degrees of dark stippling. Caudal banding is very irregular and the ground color of the tail has a slightly orange-colored hue. The venter is dull-white anteriorly becoming progressively darker posteriorly reaching a dark-gray with dense stippling beneath the tail. The lateral gular region is heavily stippled in black and the mid-gular region is much lighter. Nearly every ventral scale is marked with a large, black, diffuse, squarish, lateral blotch and all ventrals are irregularly stippled in black.

Paratypes. Variation in meristic and mensural characters are presented in Table 1. The adult male (UNS 0354) differs from the holotype in having a beige ground color with approximately 80 irregularly shaped, light-brown bands ( Fig. 2 ). The head is paler in color and stippling is restricted to the occiptal and temporal regions. The anterior two-thirds of the venter are dull-white and nearly immaculate. The posterior one-third, including the tail, is grayish with dark stippling. The retracted hemipenes are very long, bifurcated, and thin. The left hemipenis was dissected out and cut longitudinally. The bifurcation (fork) occurs at the level of the fourth subcaudal scale and the hemipenes extend to the level of approximately the 24th caudal scale, although it is difficult to determine from the right hemipenis in situ. At the base of each lobe immediately following the bifurcation are a series of enlarged soft spines but otherwise the hemipenes appear naked.

The female paratype (UNS 0355) approximates the holotype in all aspects of coloration except that the venter is much darker and the dorsum has approximately 89 body bands. Thus, dorsal coloration is likely to be sexually dimorphic.

There is no indication of sexual dimorphism in the number of ventral scales (183–186 for females, n = 2; 186 for the male). The relative length of the tail may be sexually dimorphic (TaL/TL for the male 0.23 vs. 0.15–0.15 for females and 74 subcaudals for the male vs. 54–58 for the females). Additionally, the number of dorsal body bands may be sexually dimorphic with the male having approximately 80 and the females approximately 89–92. Larger samples will be required to gain further insights into possible dimorphisms.

Distribution and Natural History. Currently, Cryptelytrops honsonensis is known only from the small island of Hon Son, Kien Hai District, Kien Giang Province in Rach Gia Bay, 61.2 km southeast of the Rach Gia city of Rach Gia Province, Vietnam ( Fig. 1 ) and is considered potentially endemic. Hon Son is a very small island (ca. 22 km 2) that reaches 405 m a.s.l. The island is composed of large granitic boulders that extend from the shoreline to its peaks and there is little to no primary vegetation remaining. Walking trails across the island have been cut through the highly degraded secondary vegetation that is heavily infused with large tracts of bamboo. The walking trails cross over large expanses of boulder outcrops that form cavities that may extend as much as 20 m below the surface of the ground. Cryptelytrops honsonensis is found among these outcrops along these trails.

The holotype (UNS 0353) was collected in the afternoon at 1600 hrs following a rain shower. It was moving over small branches of bamboo that were lying across a small pile of rocks. UNS 0 354 was collected in the early evening at 1940 hrs following an afternoon rain shower and was found coiled on the top of a large rock. UNS 0 355 was also collected during the early evening at 1930 hrs among a thicket of bamboo growing out of a large rock outcrop.

Amphibians and reptiles found in association with Cryptelytrops honsonensis and confirmed from Hon Son for the first time are Bufo melanostictus (LSUDPC 2977), Polypedates cf. leucomystax (LSUDPC 2893), Draco sumatranus (LSUDPC 3082), Calotes versicolor (LSUDPC 3036), Cyrtodactylus sp. 1 (LSUDPC 3051; Ngo & Grismer, in prep.), Cyrtodactylus sp. 2 (LSUDPC 2978–80, 3166–70, 3172–76; Grismer & Ngo, in prep.), Gekko gecko (LSUDCP 3068), Hemidactylus frenatus (LSUDPC 3179), and Hemidactylus platyurus (LSUDPC 3089).

Etymology. The specific epithet honsonensis is in reference to the type locality, Hon Son Island.

Comparisons with other species. Cryptelytrops honsonensis is readily distinguished from C. albolabris , C. erythrurus , C. insularis , C. macrops , and C. septentrionalis in being drably colored with shades of brown and dull-yellow. Additionally, it has dark body bands as opposed to being unicolor green or bright yellow and to be continued.

lacks a red tail. Cryptelytrops honsonensis has a known maximum female SVL length of 557 mm and a maximum male SVL of 523 mm, whereas C. andersoni females reach 1100 mm SVL (data unavailable for males), lacks a ventrolateral stripe which is present in C. andersoni , has 21 vs. 23 or 25 dorsal scale rows at midbody as in C. andersoni , has more ventral scales than C. andersoni in both males and females ( Table 2 ), the internasals are in contact as opposed to being separate as in C. andersoni ; C. cantori females reach 1150 mm SVL and males reach 690 mm SVL; female C. fasciatus reach 780 mm SVL; and female C. purpureomaculatus reach 900 mm SVL and males reach 665 mm SVL. Cryptelytrops honsonensis is further separated from C. purpureomaculatus by males having a longer tail (Tal/TL 0.23 vs. 0.19) and more ventral scales (186 vs. 160– 176), having smooth as opposed to keeled temporal and occipital scales, and the internasals being in contact as opposed to being separate. Female and male C. honsonensis are much larger than male and female C. labialis (SVL 557 mm vs. 372 mm for females and 523 mm vs. 340 mm SVL for males) and male C. honsonensis are larger than male C. fasciatus (SVL 523 mm vs. 406 mm).

Table 2 shows that Cryptelytrops honsonensis differs from all other species of the genus in combinations of scale counts and morphometric characteristics. These data indicate that C. honsonensis is most similar to C. kanburiensis and C. venustus but differs from both of these species in lacking a ventrolateral stripe. It is further differentiated from C. kanburiensis in that the males are larger (SVL 523 mm vs. 415 mm); the females have a thinner body (Ti 0.02–0.04 vs. 0.10–0.11); having 21 as opposed to 19 dorsal scale rows at midbody; having a higher number of ventral scales (183–186 vs. 170–178, this character is not sexually dimorphic in C. kanburiensis or C. venustus [ Malhotra & Thorpe 2004b]); having more subcaudal scales (54–88 in females vs. 41–52 and 74 in the single male vs. 59–64); having smooth as opposed to strongly keeled occipital and temporal scales; the internasals being in contact as opposed to being separated; having a wider internasal scale (W- InN/L-InN 1.7–1.9 vs. 1.4–1.6); having a wider supraocular scale (W-InN/WSupOc 1.1–1.3 vs. 0.77–0.95); and having a longer supraocular scale (L-SupOc/W-SupOc 2.3–2.5 vs. 1.7–2.2). Of all the species of Cryptelytrops , C. honsonensis is most similar to C. venustus ( Table 2 ) but differs from it further in being brownish as opposed to greenish; being larger in size (557 mm maximum SVL for females vs. 486 maximum SVL and 523 mm SVL for the single male vs. 434 mm SVL); and possibly by males having a relatively longer tail (TaL/ SVL 0.23 vs. 0.16–0.21 and 74 vs. 63–72 subcaudals).

Figures

FIGURE 1. Distribution of Crytelytrops honsonensis in Rach Gia Bay, Kien Hai District, Kien Giang Province, Vietnam.

FIGURE 2. Type specimens of Cryptelytrops honsonensis from Hon Son, Kien Hai District, Kien Giang Biosphere Reserve, Kien Giang Province, Vietnam. Upper: holotype UNS 0 353, female SVL 557 mm. Lower: paratype UNS 0 354, male SVL 523 mm.

Tables

TABLE 2. Selected diagnostic characteristics of the species of the pitviper genus Cryptelytroprs. See materials and methods for literature citations. / = character unknown. Data sources: 1 = David and Vogel (1997), 2 = David et al. (2003), 3 = David et al. (2004), 4 = De Rooij (1917), 5 = Gumprecht et al. (2004), 6 = Kramer (1977), 7 = Malhotra & Thorpe (2004 b), 8 = Manthey & Grossmann (1997), 9 = Renagass & Kramer (1981), 10 = Smith (1943) and 11 = specimens listed in Appendix.

	albolabris	andersoni	cantori	erythrurus	fasciatus	insularis	kanburiensis
Bold body bands present (1) or absent (0)	0	1	1	0	1	0	1
Ventrolateral stripe present (1) or absent (0)	0,1	1	0,1	1	0	0	1
Tail reddish (1) or not (0)	1	0	0	1	0	1	0
Color drab brownish (1) or green	0	1	1	0	1	0	1
Max SVL (mm) - females	680	1100	1150	1045	780	524	582
Max SVL (mm) - males	580	/	690	575	375	432	415
TaL/TL - females	0.16	0.15	0.12	0.16	0.20–0.21	0.35	0.13–0.14
TaL/TL - males	0.21	/	0.20	0.21	0.18–0.21	0.28	0.18
Midbody dorsal scale rows	19,21	23,25	27,29,31	23,25	21	21	19
Ventral scales - females	149–173	171–185	172–182	151–180	159–163	156–167	170–178
Ventral scales - males	150–169	171–183	171–177	153–174	158–162	156–164	172–177
Subcaudals - females	44–73	50–62	56–74	49–61	61–65	54–59	41–52
Subcaudals - males	56–78	66–78	67–76	62–79	63–65	70–75	59–61
Supralabials	7–13	10–12	11–13	9–13	9–11	7–12	10–11
Infralabials	6–16	12–14	12–14	12–14	10–11	11–14	11–13
Min. no. scales between midsection of supraoculars	8–12	9–12	13–16	11–14	6–10	9–12	7–9
Occipitals and temporals strongly keeled (1) or smooth to weakly keeled (0)	0	0	0	1	0	0	1
Internasals separate (1) or in con- tact (0)	0,1	1	1	0,1	1	0	1
4th supralabial in contact with sub- ocular (1) or not (0)	0,1	0	0	0	0	0	0
3rd supralabial in contact with sub- ocular (1) or not (0)	1	0,1	0	0,1	0	1	0,1
Sample size	187	23	Not given	13	6	65	3
Data source	1,9, 10,11	6,10	5,10	1,9, 10	2,4	6,9	8