Amphiesma andreae, Ziegler, Thomas & Quyet, Le Khac, 2006

Ziegler, Thomas & Quyet, Le Khac, 2006, A new natricine snake of the genus Amphiesma (Squamata: Colubridae: Natricinae) from the central Truong Son, Vietnam, Zootaxa 1225, pp. 39-56 : 41-52

Amphiesma andreae sp. n.

Figures 1–9.

Holotype

A male ( ZFMK 83747), adjacent to Phong Nha — Ke Bang National Park, Thuong Hoa commune, Minh Hoa district, Quang Binh Province, central Vietnam, collected on 8 August 2004 in a limestone forest valley at an elevation of 450 m.

Diagnosis

Amphiesma andreae sp. n. can be distinguished from all congeners on the basis of the following combination of characters: 1) Body and tail slender, tail cylindrical and tapering; tail/total length ratio 0.31; 2) the eye diameter, if projected forward, reaches beyond the suture of first and second supralabial; 3) a single loreal; 4) a single preocular; 5) three postoculars; 6) a single anterior followed by a single posterior temporal; 7) nine supralabials, fourth to sixth in contact with the eye, eighth supralabial largest; 8) nine infralabials, first pair in contact behind the mental, the first five border the anterior chinshields; 9) posterior chin­shields longer than anterior ones, separated on their entire length by gular scales; 10) 179 ventrals (plus two preventrals); 11) anal plate divided; 12) 99 divided subcaudals; 13) dorsal scales in 19­19­17 rows, keeled (except outermost row in the anterior body) with a narrow, sharp keel; 14) dorsal ground coloration brownish­olive, with a pale, black­edged bar before and behind the eye; head and neck with several pale, dark­edged blotches that turn into pale and black­edged transversal bars on the anterior body; such a transversal bar pattern dissolves anterior to the midbody region and then turns into a series of small pale blotches that build each a dorso­lateral stripe that ends at the dorsal tail base; 15) venter light, laterally with dark spots in the forebody region; 16) 34 maxillary teeth, arranged in a continuous series, the two posteriormost distinctly enlarged, without diastema; 17) hemipenis simple, with undivided sperm groove; the outer genital organ is covered with small spines except for a single, strongly enlarged spine next to the sperm groove at the hemipenis base and except for irregularly arranged mediumsized spines that encircle the hemipenis horizontally at the trunco­pedicel area.

Description of holotype

Total length 608 mm, snout­vent length 420 mm, and tail length 188 mm; tail/total length ratio 0.31. Body and tail slender, tail cylindrical and tapering. The head is moderately distinct from the neck. The distance between the anterior corner of the large eye (with rounded pupil), and the snout tip (5.0 mm each) is larger than the horizontal diameter of the eye (3.3–3.4 mm); the eye diameter, if projected forward from the anterior rim of the orbit, reaches beyond the suture of first and second supralabial.

Rostral wider than high, narrowly visible from above. Supranasals slightly longer than wide, somewhat truncate anteriorly. Suture between the supranasals slightly longer than the suture between the prefrontals, which are wider than long. Frontal longer than its distance from the snout tip, about equal in length to the interparietal suture. Parietals long and wide, shorter than their combined width, squarely truncate posteriorly. Nasal distinctly longer than high, divided into two parts on the lower half, with a rounded, lateral nostril in its middle. The anterior portion of the nasal is longer than the higher posterior portion. The single loreal is as broad as high, narrowing upwards. The single preocular is much higher than broad. Three postoculars, the upper one being the largest. One anterior and one posterior temporal. Nine supralabials, first and second in contact with the nasal, second to fourth in contact with the loreal, and fourth to sixth in contact with the eye, the eighth supralabial being the largest. Nine infralabials, first pair in contact behind the mental, the first five border the anterior chin­shields. Posterior chin­shields the longer pair, separated their entire length by gular scales. Gular scales between posterior chin­shields consist of a pair of tiny scales just behind the posterior tips of the anterior chin­shields, followed by a medium­sized scale and subsequently by a pair of large scales, posteriorly bordering the first preventral. 179 ventrals (counted according to Dowling 1951) plus two preventrals; anal plate divided; 99 divided subcaudals (terminal scute excluded). Dorsal scales one head length behind head and at midbody in 19 rows, one head length before vent in 17 rows. Dorsal scale rows distinctly keeled with a narrow, sharp keel; somewhat beyond midbody also outermost dorsal scale row with distinct keel.

The formaldehyde­fixed and subsequently ethanol­preserved holotype has a greyishbrown dorsum, with the anterior portion of the body appearing lighter and the posterior body and tail rather dark. The anterior portion of the prefrontals and the supranasals is somewhat paler, the rostral, nasal, loreal, preocular, lower postoculars and supralabials are at least in part beige (usually with dark suture areas). There is a black­edged, creamcoloured, vertical bar that covers the preocular and the fourth supralabial. Another distinct, black­edged and cream­coloured bar stretches from the lower postoculars along the anterior portion of the anterior temporal to the seventh supralabial. A cream­coloured, black­edged blotch covers the ninth supralabial. The parietals are light brown, and this coloration stretches along the anterior temporal to the eighth supralabial. In the centre region of the parietal suture there is a pair of small cream, black­edged blotches. In addition, about ten such cream and black­edged blotches encircle the outer parietal border area, with the blotches becoming somewhat larger towards the neck region. A pair of black­edged, cream blotches is located just behind the head on the top of the neck, followed by another pair of light, black­edged blotches in a distance of about 5 mm. Below these two pairs of blotches there is a light blotch covering each of the two to three outermost dorsal scale rows. Between the light blotch on the ninth supralabial and the first pair of light neck blotches there is another pale, dark­edged blotch on each side. After the second pair of light neck blotches there are eleven pale transversal bars discernible. These black­edged, one to two scales wide bars are irregularly arranged and partly interrupted in the neck region, but the posterior four bars are continuous. These pale bars contain small dark blotches and widen somewhat towards the venter, where they usually encircle one or two distinct dark blotches. However, these large dark blotches are located on the ventral shields. At the position of the sixty­first ventral (120 mm behind the head) the pale transversal bands dissolve into irregular arranged pale blotches, that become smaller and smaller. From the midbody region towards the dorsal tail root the only pattern discernible consists of a dorso­lateral row, built of small pale blotches with a diameter of about 1 mm which are arranged in a distance to each other of one to two dorsal scales’ width. The tail dorsum appears dark greyish­brown, although the dark dorsal body and tail scales bear a paler mottling at closer view. The venter is cream colour, except for small dark markings in the lateral and posterior head region and except for the above­described black blotches at the lateral ends of some ventral scales in the neck and forebody region. The outermost corners of the ventrals and subcaudals are dark and the venter of the tail is in part powdered by dark brownish­grey.

In life, the head and anterior neck region are reddish­brown to brownish­olive, turning posteriorly into dark brownish­grey. The pale bars and blotches in the head and anterior neck region are white to cream, whereas the remaining pale neck bars turn into yellowish and after having been dissolved into yellowish­orange.

The maxillary teeth are arranged in a continuous series, with the two posteriormost distinctly enlarged, without diastema, numbering 34 on each side; for counting the maxillary teeth, the exterior gum surfaces of the jaw were removed in situ (tooth sockets were included in the counts in cases of tooth loss). The uniqueness of the specimen precluded any further investigation of the skull and skeleton.

The invertedly dissected left hemipenis revealed (as far as detectable) to be simple, with an undivided sperm groove (sulcus spermaticus), that apparently runs straight to the apex (for terminology see Ziegler & Böhme 1997). In general, the organ is armed with small spines from the base to the tip, with the exception of the sulcus spermaticus. At the base of the hemipenis there is a single, strongly enlarged spine discernible next to the sperm groove. In addition, in this pedicel­truncus border area, numerous medium­sized spines, that are irregularly arranged, horizontally encircle the hemipenis.

Etymology

The species is named after Andrea Ziegler in recognition of her patience and support during the last decade of herpetological research of the senior author in Vietnam. We suggest the following western common names: Andrea’s Keelback (English), Ran sai Andrea (Vietnamese), Amphiesma d’Andrea (French) , and Andreas Gebirgswassernatter ( German).

Comparisons

David et al. (1998) listed 37 valid Amphiesma species and David & Das (2003) recently increased the species number to 39 (see also David et al. 2005); Tillack (2002) judged A. sieboldii (Günther, 1860) as being synonymous with A. platyceps (see also Kramer 1977), but A. sieboldii is regarded as a valid species in David et al. (1998, 2005).

The new Amphiesma species can be distinguished from all the remaining species not only by a distinct pattern and coloration, but also by different teeth and scale counts: Amphiesma atemporale ( Bourret, 1934) differs from the new species in having only 28–30 maxillary teeth, 5–6 supralabials (with 3–4 entering the eye), 6–7 infralabials, 17 midbody scale rows, 129–146 ventrals, 54–79 subcaudals, and a pale collar across the neck ( Smith 1943, Malnate & Romer 1969); A. beddomei (Günther, 1864) has only 140–150 ventrals, 62–82 subcaudals, a broad, black­outlined white stripe behind the eye, and a brown back with variable black and dull yellow or white pattern ( Smith 1943; see photo in Das 2002, Whitaker & Captain 2004); A. bitaeniatum (Wall, 1925) bears 19–23 maxillary teeth, 7–8 supralabials (3–5 entering orbit), 160–175 ventrals, 78–95 subcaudals and has a distinct, broad, pale and continuous dorsolateral stripe from neck to the end of tail (Pope 1935, David et al. 2005; see photos in Chan­ard et al. 1999, as determined by David & Pauwels 2000, and photos in David et al. 2005); A. boulengeri ( Gressit, 1937) differs by having 28 maxillary teeth in a continuous series, gradually becoming larger toward the posterior end, 143–147 ventrals, two postoculars, a pair of pale longitudinal dorsal stripes, and a typical postocular streek ( Gressit 1937, Malnate 1960); A. celebicum (Peters & Doria, 1878) has only 8 supralabials (3–5 entering the eye), 15 midbody scale rows, 125–142 ventrals, 45–53 subcaudals, and a black collar that is posteriorly edged with a yellow band and anteriorly with two yellow spots ( Boulenger 1893, de Rooij 1915); A. concelarum Malnate, 1963 bears a different hemipenial spine ornamentation, only 25–26 maxillary teeth, 8 supralabials (4–5 in contact with the eye), two anterior and two posterior temporals each, 157–169 ventrals, and a dorsal pattern on each side of anterior 1/3 to 1/2 of the body consisting of several light vertical streaks, each of one scale’s width or narrower ( Malnate 1963, Mori 1986, Ota & Iwanaga 1997; see photos in Mori 1986, Ota & Iwanaga 1997); A. craspedogaster ( Boulenger, 1899) differs in having 8 supralabials (3–5 entering the eye), 138–159 ventrals, and a dark brown dorsum with a rusty­red streak along each side of the back, accompagnied by more or less distinct yellowish spots ( Boulenger 1899, Pope 1935); A. deschauenseei (Taylor, 1934) has two preoculars and two postoculars each, two posterior temporals, 159 ventrals, 137–140 subcaudals, a small eye, brownish­yellow body sides which are heavily mottled with irregular black blotches, and of the nine supralabials only the fifth and sixth touch the eye ( Bourret 1936, Cox 1991, see photos in Cox 1991); A. flavifrons (Boulenger, 1887) has 7–9 supralabials (4–5 or 5–6 touching the eye), 2 anterior temporals, 146–157 ventrals, the anal scute entire, a belly with large dark spots, a white stripe across prefrontals and frontal, and a greenish dorsum with a vertebral row of light spots ( Malkmus et al. 2002, David & Das 2003; see photo in Malkmus et al. 2002); A. frenatum (Dunn, 1923) has in contrast 8 supralabials, 2 anterior temporals, 17 dorsal scale rows at midbody, 164–166 ventrals, 112–116 subcaudals, a belly with large dark spots, and a dorsal pattern consisting of dorsolateral spots and crossbars ( David & Das 2003); A. groundwateri (Smith, 1921) shows 2 preoculars, 17 midbody scales, 147–154 ventrals, 120–134 subcaudals, a single anal shield, and a dorsal pattern consisting of an undulating dorsolateral stripe ( Cox 1991, David & Das 2003; see photo in. Nutphand 2001); A. inas (Laidlaw, 1901) differs by having two posterior temporals, 143–151 ventrals, and an alignment of dorsolateral spots ( Bourret 1936, Cox 1991, David & Das 2003; see photos in Cox et al. 1998, Chan­ard et al. 1999, Nutphand 2001); A. ishigakiense ( Malnate & Munsterman, 1960) has a different hemipenial spine ornamentation, only 8 supralabials (with only 4–5 in contact with the eye), 10 infralabials, 172–175 ventrals, and a dorsal pattern on each side of anterior 1/3 to 1/2 of the body consisting of several light vertical streaks, each of one scale’s width or narrower ( Mori 1986, Ota & Iwanaga 1997; see photos in Mori 1986, Ota & Iwanaga 1997); A. johannis (Boulenger, 1908) has 7–8 supralabials (3–5, 3–4 or 4–5 entering the eye), 1–2 preoculars, a frontal as long as its distance from the snout tip, 2 anterior and 1–2 posterior temporals, 165–176 ventrals, the lateral dorsal scales not keeled, a rather small eye, and an olivebrown dorsum with more or less distinct darker and lighter spots, the latter forming a lateral series or an ill­defined lateral streak (Pope 1935, Bourret 1936); A. kerinciense David & Das, 2003 has 2 posterior temporals, 11 infralabials, 140 ventrals, 89 subcaudals, and a faint pale ochre brown dorsolateral stripe bordering the dark vertebral band on each side ( David & Das 2003; see also photos in David & Das 2003); A. khasiense (Boulenger, 1890) bears 26–28 maxillary teeth, 10 infralabials, 143–162 ventrals, and the dorsum has three dark blackish­brown stripes that alternate with four reddish­brown stripes ( Smith 1943, Campden­Main 1970, Whitaker & Captain 2004; see photo in Whitaker & Captain 2004); A. metusia Inger, Zhao, Shaffer & Wu, 1990 has 8 supralabials, 159–164 ventrals in females, 72–85 subcaudals, and a distinct, broad, pale and continuous dorsolateral stripe from neck to the end of tail ( Inger et al. 1990, David et al. 2005); A. miyajimae ( Maki, 1931) bears 20 maxillary teeth, 8 supralabials (3–5 entering the eye), 141–152 ventrals, and a brown dorsum with three black longitudinal bands ( Maki 1931; see photos in Zhao & Adler 1993, Lu et al. 1999); A. modestum (Günther, 1875) has 28–32 maxillary teeth, two preoculars, 10 infralabials, 143–168 ventrals, small eyes, and the body is brown above with small black spots and small yellow spots on the sides which may form a stripe ( Smith 1943, Campden­Main 1970; see photos in Cox et al. 1998, Das 2002, Nguyen et al. 2005); A. monticola (Jerdon, 1853) has 2 anterior and 2–3 posterior temporals, 8 supralabials (3–5 touching the eye), 136–144 ventrals, 78–92 subcaudals, a white or yellow line across back of head behind the eye, and an olive brown or greenish back with broad black cross­bands or big squarish spots, which may be paired, and may have lighter spots or cross­lines in between ( Smith 1943; see photos in Whitaker & Captain 2004); A. nicobarense (Sclater, 1891) has 25 maxillary teeth, 7–8 supralabials (3–4 or 4–5 touching the eye), 160 ventrals, 120 subcaudals, an entire anal shield, and is greenish­olive above, with three light, blackedged stripes ( Smith 1943); A. octolineatum (Boulenger, 1904) usually has 8 supralabials (usually 4–5 in contact with the eye), 2 anterior and 2 posterior temporals, 151–167 ventrals, 58–77 subcaudals, and a distinct, broad, pale and continuous dorsolateral stripe from neck to the end of tail (Pope 1935, Bourret 1936, David et al. 2005); A. optatum (Hu & Djao, 1966) has only up to 25 maxillary teeth, (6) 7–8 supralabials (of which 3–4, 3–5 or 4–5 enter the orbit), 152–169 ventrals, a very bright coral red venter, and a deep bluish black dorsal surface that is marked on each side with bright yellowish vertical bars ( David et al. 1998; see photos in David et al. 1998, and in Orlov et al. 2003); A. parallelum (Boulenger, 1890) bears 20–24 maxillary teeth, 8 supralabials (3–5 in contact with the eye), the enlarged posterior maxillary teeth are separated from others by a distinct diastema, and the species has a distinct broad, pale and continuous dorsolateral stripe from the neck to the end of tail, and a nearly always present black preocular streak on preocular and loreal ( Smith 1943, David et al. 2005); A. pealii (Sclater, 1891) differs in having only 19–21 maxillary teeth, 2 anterior and 2 posterior temporals, 9 supralabials (only 4–5 touching the eye), 142–144 ventrals, 75–77 subcaudals, and a brown dorsum with a narrow light dorso­lateral stripe and a broader pale one occupying scale rows 1 and 2 ( Smith 1943); A. petersii ( Boulenger, 1893) has two anterior temporals, 134–150 ventrals, 65–93 subcaudals, and a dorsal pattern of black and pale rounded spots ( Tweedie 1961, David & Vogel 1997, Malkmus et al. 2002, David & Das 2003); A. platyceps (Blyth, 1854) bears 19–21 maxillary teeth, only 8 supralabials (3–5 touching the eye), body sides may be striped, and back with small black spots and sometimes with series of short white lines that run along the body ( Smith 1943; see photo in Das 2002, Whitaker & Captain 2004); A. popei ( Schmidt, 1925) has 20 maxillary teeth, 8 upper labials (4–5 entering the eye), 130–137 ventrals, and 78–86 subcaudals ( Schmidt 1925); A. pryeri (Boulenger, 1887) has a different hemipenial spine ornamentation, 7–9 supralabials (only two reach the eye), 112–130 subcaudals, a dorsal pattern on each side of anterior 1/3 to 1/2 of the body consisting of several light vertical streaks that lack black edges, and the lectotype BMNH 1946.1.7.63 has only 25 maxillary teeth ( Mori 1982, Ota & Iwanaga 1997; see photos in Mori 1982, Ota & Iwanaga 1997); A. sanguineum (Smedley, 1932) has 2 preoculars, 140–155 ventrals, and a dorsal pattern consisting of a vertebral band and crossbars ( Tweedie 1961, David & Das 2003; see photo in Chan­ard et al. 1999); A. sarasinorum (Boulenger, 1896) has 8 supralabials (3–5 entering the eye), 15 midbody scale rows, 137–141 ventrals, 65–75 subcaudals, and the dorsum is reddish brown anteriorly, olive or dark grey behind, with blackish transverse bands (de Rooij 1915); A. sarawacense (Günther, 1872) has two anterior temporals, 17 midbody scale rows, 134–154 ventrals, and a dorsal pattern consisting of dark and light square blotches ( Malkmus et al. 2002, David & Das 2004; see photo in Malkmus et al. 2002); A. sauteri (Boulenger, 1909) has 22–23 maxillary teeth, 7 supralabials (two entering the eye), 17 midbody scale rows, 118–131 ventrals, and a brown dorsum with small black spots, with a rather ill­defined reddishbrown streak on each side of the back, bearing a series of distinct small pale spots on the anterior body ( Maki 1931, Smith 1943; see photo in Lu et al. 1999); A. sieboldii (Günther, 1860) has among others (see discussion above and compare also data in Malnate 1966) 191–207 ventrals in males, dorsal surfaces usually uniformly brown, except for a dorsolateral series of well­defined small white spots, venter often largely speckled with dark greyish­brown posteriorly, and subcaudal surface usually dark ( David et al. 2005); A. stolatum (Linnaeus, 1758) bears 21–24 maxillary teeth, 7–8 supralabials (3–5 in contact with the eye), 118–161 ventrals, 50–89 subcaudals, and a brown back with two distinct yellowish stripes from neck to tip of tail ( Bourret 1936, Smith 1943, Campden­Main 1970; see photos in Cox 1991, Zhao & Adler 1993, Cox et al. 1998, Chan­ard et al. 1999, Lu et al. 1999, Nutphand 2001, Das 2002, Whitaker & Captain 2004); A. venningi (Wall, 1910) has 27–32 maxillary teeth, 17 midbody scale rows, 155–176 ventrals, and an olive brown back with sometimes indistinct black checks or spots ( Smith 1943, Whitaker & Captain 2004; see photos in Das 2002, Whitaker & Captain 2004); A. vibakari (Boie, 1826) has 7–8 supralabials, 127–153 ventrals, 62–89 subcaudals, and a dorsum usually with an indistinct pale stripe on the 4th to 7th scale rows, occasionally containing small light spots ( Malnate 1962, Mori 1984, Ota & Iwanaga 1997; see photo in Mori 1984); A. viperinum (Schenkel, 1901) has 7 supralabials (3–4 entering the orbit), 2 anterior temporals, 101 ventrals, 59 subcaudals, and a dorsal pattern consisting of a dorsolateral stripe and crossbars ( David & Vogel 1997, David & Das 2003); and A. xenura (Wall, 1907) differs from the new species by having only 22–23 maxillary teeth, usually 9 supralabials (3–4 touching the eye), 2 anterior and 2 posterior temporals, 158–165 ventrals, dorsum with a series of paired reddish­orange, pale brown, yellow or white spots on each side of upper back, and adjacent spots sometimes connected by faint black cross­lines ( Smith 1943, Whitaker & Captain 2004; see photo in Whitaker & Captain 2004).

Similar to Amphiesmoides ornaticeps , our new species also bears a conspicuous light, black­edged, vertical bar extending upward from the mouth immediately behind the eye and another similar one just anterior to the eye, over preocular and fourth supralabial (as given as a key feature in Pope 1935, Yang & Inger 1986, Zhao & Adler 1993), but A. ornaticeps in contrast shows large, squarish, dark spots in the anterior body dorsum, which are separated by narrow, cream­colored interspaces, and a grayish­black dorsal stripe on the posterior two­thirds of body and tail ( Malnate 1961, compare the photograph of the holotype of Natrix andrewsi Schmidt, 1925 on plate 32 in Zhao & Adler 1993, a synonym of Amphiesmoides ornaticeps ). According to Malnate (1961) A. ornaticeps also bears a light ventrum, that has irregular, dark markings at the outer corners of each ventral, which become finer posteriorly and are indistinct subcaudally. With respect to scalation differences, A. ornaticeps has anteriorly broader internasals, a distinctly higher subcaudal scale count (116–128), a lower ventral count (157–168), more temporal scales (1–2 + 2–4) and usually four (but occasionally three) postoculars ( Schmidt 1925, Pope 1935, Bourret 1936, Malnate 1961). A. ornaticeps also bears a different hemipenial spine ornamentation and more maxillary teeth (42–46), that are arranged in a continuous series, gradually becoming larger posteriorly ( Malnate 1961). Indeed, Fan (1931) only counted 28 maxillary teeth in the species ornaticeps and Schmidt according to Pope (1935) only 37 maxillary teeth on the type of Natrix andrewsi , but this most likely is based on miscounts, as Pope (1935) counted 45 maxillary teeth on the same N. andrewsi type specimen. In addition, according to Malnate (1961) the eye is conspicuous in A. ornaticeps (ca. 25 % of the head length), with the eye diameter projected forward from the anterior rim of the orbit reaching the suture between rostral and nasal, which is not the case in Amphiesma andreae sp. n.

Distribution and natural history

Amphiesma andreae sp. n. is only known from its type locality ( Figure 10 ). Records for Laos are expected in the future, due to the close proximity of the type locality to the Laotian border.

The male holotype (ZFMK 83747) was found during the late afternoon on the forest ground between the roots of a large tree. This tree was about ten metres away from a large stream running through a wide limestone forest valley.

Figures

FIGURE 10. Type locality of Amphiesma andreae sp. n. in Quang Binh Province, central Vietnam.