On the occurrence of Amphiesma bitaeniatum (Wall, 1925) in Vietnam, with preliminary remarks on the group of Amphiesma parallelum (Boulenger, 1890) (Serpentes, Colubridae, Natricinae)

2005·3.2 MB·English

by  David, P

On the occurrence of Amphiesma bitaeniatum in Vietnam
SALAMANDRA 41 4 167-178 Rheinbach,20 November 2005 ISSN 0036-3375
On the occurrence of Amphiesma bitaeniatum (W , 1925)
ALL
in Vietnam, with preliminary remarks on the group of
Amphiesma parallelum (B , 1890)
OULENGER
(Serpentes, Colubridae, Natricinae)
PATRICK DAVID, GERNOT VOGEL & OLIVIER S. G. PAUWELS
Abstract. A specimen of the natricine Amphiesma bitaeniatum was recently collected near Sapa, northern
Vietnam. This specimen confirms the occurrence of this species in Vietnam, first mentioned by POPE in
1935 on the basis of a specimen from Mt. Fan Si Pan, subsequently overlooked by other authors. Both
specimens are described and compared with other preserved specimens. Amphiesma bitaeniatum is now
known from Myanmar, China, Vietnam and Thailand. This species is compared with Amphiesma
parallelum and Amphiesma octolineatum. Main differences in pattern and coloration are discussed, and
a key to the species similar to A. bitaeniatum is provided.
Key words. Serpentes: Colubridae: Amphiesma bitaeniatum, Amphiesma octolineatum, Amphiesma
parallelum; Vietnam.
Introduction (BMNH 1930.11.16.5). This record was
largely overlooked by subsequent authors or
The Asian genus Amphiesma DUMÉRIL, BIBRON was cited as Amphiesma parallelum (BOULEN-
& DUMÉRIL, 1854 is currently composed of 39 GER, 1890), as for example by NGUYÊN & HÔ
species (DAVID & DAS 2003), but its content is (1996).
still provisional. It should be modified Amphiesma bitaeniatum was tentatively
shortly due to the discovery of yet unde- included by MALNATE (1960) in an informal
scribed taxa (see, for example, ZIEGLER 2002: subgroup also including Amphiesma paral-
219) and the re-evaluation of the status of lelum and Amphiesma octolineatum (BOULEN-
currently recognized species. During a her- GER, 1904). These species from the Eastern
petological survey in the region of Sapa, Himalayas and neighbouring areas are char-
Province of Lào Cai, Vietnam, the second acterized by a distinctly longitudinally
author obtained a snake that we identified as striped pattern and are morphologically very
Amphiesma bitaeniatum (WALL, 1925). This similar. As an obvious consequence, their
species was originally described as Natrix identification is rather difficult, and the con-
bitaeniata by WALL (1925: 806; type local- fusion among these species has long been
ity: “Kutkai, North Shan States, Burma: 6000 extensive in the literature. The present paper
feet”, now Kutkai, Shan State, Myanmar). is only the first step, emphasizing the diag-
However, the specimen from Sapa is not the nostic characters of these three species, to-
first one to have been recorded from Viet- wards a more comprehensive study of species
nam. POPE (1935: 100) briefly cited (as Natrix related to Amphiesma parallelum.
bitaeniata), without description, a specimen We describe these two Vietnamese speci-
of Amphiesma bitaeniatum collected on mens of Amphiesma bitaeniatum, and com-
“Fan-Si-Pan, Lao Kay, Tongking”, now Mt. pare them to preserved specimens from My-
Phang Si Pang, Bình Thuân Province anmar and China, and with data from the
© 2005DeutscheGesellschaftfürHerpetologieundTerrarienkundee.V.(DGHT)
http://www.salamandra-journal.com 167
PATRICK DAVID et al.
literature. Two other species, relatively simi- TaL/TL: ratio tail length / total length.
lar in morphology, Amphiesma platyceps DSR: dorsal scale rows; IL: infralabials;
(BLYTH, 1854) and Amphiesma sieboldii K1R: keeling of first DSR at midbody;
(GÜNTHER, 1860), are also discussed, as they KSR: keeling of dorsal scale rows at mid-
have been confused with Amphiesma paral- body; MSR: number of dorsal scale rows at
lelum. Lastly, Amphiesma bitaeniatum has midbody (see above); PoO: postoculars; PrO:
also been largely confused with Amphiesma preocular(s); PSR: number of dorsal scale
octolineatum and Amphiesma metusia INGER, rows before vent (see above); SC: subcau-
ZHAO, SHAFFER & WU, 1990. On the basis of dals; SL: supralabials; Te: temporals; VEN:
recently collected specimens and the inves- ventrals.
tigation of characters not considered by pre- Museum abbreviations used are as fol-
vious authors, we provide an artificial key to lows: AMNH, American Museum of Natural
these six rather similar species. History, New York; BMNH, British Museum
(Natural History), London; CAS, California
Academy of Sciences, San Francisco; CIB,
Materials and methods Chengdu Institute of Biology, Academia Si-
nica, Chengdu; FMNH, The Field Museum,
This study is based on the examination of 96 formerly the Field Museum of Natural His-
specimens referred to the species Amphiesma tory, Chicago; KSC, Kohima Science Col-
bitaeniatum, Amphiesma octolineatum, Am- lege, Kohima; MHNG, Museum d’Histoire
phiesma parallelum, Amphiesma metusia, Naturelle, Geneva; MNHN, Muséum Natio-
Amphiesma platyceps and Amphiesma sie- nal d’Histoire Naturelle, Paris; NRCT, Natio-
boldii. Examined specimens are listed in the nal Research Council of Thailand, Bang-
Appendix. Investigated characters are dis- kok; SMNH, Shanghai Museum of Natural
cussed below. All measurements are in milli- History, Shanghai; ZSI/ERS, Zoological
metres (mm). Body and tail lengths were Survey of India (Eastern Region Station),
measured to the nearest millimetre. All other Shillong.
measurements were taken with a slide-calli-
per to the nearest 0.1 mm. Ventral scales were
counted according to DOWLING (1951). The Results
terminal scute is excluded from the number Description of Vietnamese specimens
of subcaudals. The number of dorsal scale
rows is given at one head length behind BMNH 1930.11.16.5, an adult female from
head, at midbody (i.e. at the level of the “Fan-Si-Pan, Lao Kay, Tongking”, now Mt.
ventral plate corresponding to half of the Phang Si Pang, Bình Thuân Province, col-
total ventral number), and at one head length lected by DELACOUR & LOWE. MNHN 1999.
before vent, respectively. Values for symmet- 9090 (Figs. 1-4), an adult female, from the
ric head characters are given in left/right vicinity of Sapa, Lào Cai Province, at about
order. 1800 m a.s.l., collected in June 1998 by G.
Abbreviations used for measurements VOGEL. The latter specimen was collected in
and meristic characters are: HDE: horizontal a rocky area covered with bushes and single
diameter of eye; HL: head length; LPr: trees, under cool and cloudy weather condi-
length of prefrontal; RIn: ratio of width of tions. In the following description, the first
anterior margin of internasals/posterior mar- and second values given for each character
gin of internasals; SnL: snout length (dis- refer to those of BMNH 1930.11.16.5 and
tance between the snout tip and the anterior MNHN 1999.9090, respectively. Unless oth-
margin of the eyes); SVL: snout-vent erwise mentioned, the state or value of a
length; TaL: tail length; TL: total length; given character is shared by both specimens.
168
On the occurrence of Amphiesma bitaeniatum in Vietnam
Fig. 1. Dorsal view of Amphiesma bitaeniatum (MNHN 1999.9090) from the vicinity of Sapa, Lào Cai
Province, Vietnam (specimen freshly killed by forest workers).
Fig. 2. Close-up view of Amphiesma bitaeniatum Fig. 3. Ventral view of Amphiesma bitaeniatum
(MNHN 1999.9090) from the vicinity of Sapa, Lào (MNHN 1999.9090) from the vicinity of Sapa, Lào
Cai Province, Vietnam. Cai Province, Vietnam.
Habitus: Body moderately elongated, cylin- for 24.3 and 26.6 % of HL respectively, 1.6
drical; head elongate, rather narrow, barely times as long as HDE, slightly flattened,
distinct from neck; snout long, accounting narrowing up at its tip which is blunt when
169
PATRICK DAVID et al.
seen from above, rounded seen from side, tact with nasals, 2nd-3rd SL in contact with
with no defined canthus rostralis; nostril lat- loreal, 3rd-5th SL entering orbit (no subocu-
eral; eye large, its diameter 2.0 and 2.5 times lar), 7th SL largest; 1/1 PrO; 3/3 PoO; 2+1/
the distance between its inferior margin and 2+1 Te and 1+1/1+1 Te respectively; 10/10
upper lip edge; pupil round; tail long, cylin- IL in both specimens.
drical and progressively tapering.
Coloration: BMNH 1930.11.16.5: In alco-
Dentitional morphology: Maxillary teeth hol, dorsal surfaces are dark brownish grey
(on the right side of head): BMNH 1930.11. above (DSR 8-10 before VEN 100, 7-9 be-
16.5: 19 subequal + 2 distinctly enlarged hind), pale beige brown on the sides, dis-
teeth, without diastema. MNHN 1999.9090: tinctly paler than on the back, with many
17 subequal + 2 distinctly enlarged teeth, scales of both the sides and the back edged
without diastema. with blackish-brown. The vertebral row is
distinctly paler than adjacent scales. A con-
Measurements and scalation: BMNH 1930. spicuous pale yellow-ochre dorsolateral
11.16.5: SVL 520 mm; TaL 188 mm; TL 708 stripe extends on 5th, 6th and 7th DSR (4th,
mm. Ratio TaL/TL: 0.266. VEN: 166 (+ 2 5th, 6th respectively behind VEN 100), bor-
preventrals); SC 86, all paired; anal divided. dered below with a well defined, single,
DSR 19-19-17, strongly keeled on the upper blackish-brown line on upper half of DSR 4
part of the back, less keeled on the lower and lower part of DSR 5, and above by a
rows, smooth on 1st DSR, all distinctly and thinner and fainter irregular, discontinuous
deeply notched at their apical part, espe- blackish-brown line on the extreme upper
cially on the posterior part of the body. No part of DSR 7. The dorsolateral beige yellow
apical pit. Dorsal scale row reductions: 19- stripe extends forwards on the neck and on
17: right, 3+4 (VEN 99)/left, 3+4 (VEN 100). upper side of the head where it distinctly
MNHN 1999.9090: SVL 494 mm; TaL 160 widens and becomes paler and more con-
mm; TL 654 mm. Ratio TaL/TL: 0.245. spicuous behind the upper temporals. The
VEN: 174 (+ 2 preventrals); SC 76, all paired; lower blackish-brown line widens signifi-
anal divided. DSR 19-19-17, more or less cantly on the side of the neck and is con-
strongly keeled on the upper part of the back, nected without constriction to the black
less keeled on the lower rows, smooth on first postocular streak, whereas the upper dark
DSR, all distinctly and deeply notched at line extends forwards up to the occipital
their apical part, especially on the posterior region, ending at the same level than the
part of the body. No apical pit. Dorsal scale ivory dorsolateral stripe. Scales of DSR 1
row reductions: 19-17: right, 3+4 (VEN 100)/ marked with faint and irregular blackish-
left, 3+4 (VEN 100). Rostral 1.6 times as wide brown short streaks on their anterior margin,
as high; nasal rectangular, longer than high, producing a very discontinuous zig-zag ven-
divided into two parts, with a lateral nostril trolateral line. Upper tail surface as the body,
piercing between the two parts of the nasal; the dark brown colour of the back and the
internasals subtriangular, slightly longer ivory yellow stripe merging toward the end
than wide, anteriorly narrowed but truncated of the tail. The lower lateral blackish-brown
with RIn about 0.60; suture of parietals about stripe of the body and the ventrolateral zig-
0.8 time as long as frontal; frontal ogive- zag like line joins a short distance behind
shaped, 1.5 and 1.7 times as long as wide; vent, and extends as a single blackish-brown
prefrontals barely longer than internasals up to the tail tip; the upper lateral stripe
and wider, reaching loreal; one large, undi- vanishes progressively a short distance be-
vided supraocular on each side; one subrec- hind vent. Head greyish-brown above, with
tangular loreal, slightly longer than high; 8/ weak vermiculations. Sides of snout slightly
8 SL in both specimens, 1st-2nd SL in con- paler, pale yellowish-brown, without darker
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On the occurrence of Amphiesma bitaeniatum in Vietnam
streak in front of the eye. Supralabials pale line extends forwards up to the occipital
ivory yellow; SL 1st to 5th spotted with dark region, ending at the same level than the
brown. A conspicuous, broad dark brown ivory dorsolateral stripe. Scales of DSR 1
postocular streak extending from behind the marked with faint and irregular blackish-
eye to the corner of the mouth, running on brown short streaks on their anterior margin,
lower PoO, first temporal, upper part of SL 6 producing a discontinuous zig-zag ventrola-
(creamy yellow bottom), centre of SL 7 and teral line. Upper tail surface as the body, the
lower half of SL 8, scale on which it is rather dark brown colour of the back and the ivory
irregular dark greyish-brown. Seventh supra- yellow stripe merging toward the end of the
labial is pale cream yellow on its lower part tail. The lower lateral blackish-brown stripe
and greyish-brown, as upper head surface, on of the body and the ventrolateral zig-zag like
its upper part; SL 8 is yellowish-ochre on its line joins a short distance behind vent, and
upper part which belongs to the end of the extends as a single blackish-brown up to the
dorsolateral stripe. The side of the neck is tail tip; the upper lateral stripes vanish pro-
bright pale yellowish-ochre above, with a gressively a short distance behind vent. Head
wide, blackish brown, continuous stripe in greyish-ochre above, with weak vermicula-
its middle part resulting from the continuity tion, slightly paler, pale yellowish-brown on
of the postocular streak which connects with the snout side, but without any darker mark-
the ochre-brown colour of the lower half of ing; background colour of supralabials
the body, and is ivory yellow on its lower bright yellow in life, pale ivory yellow in
part. Eye black. Venter creamy yellow, with, alcohol; SL 1-5 marked with thin blackish-
on each side of ventral scales, an elongated brown sutures on their upper and posterior
small dark brown spot near the outer margin parts; a conspicuous dark brown postocular
of the scale at about 3/4 of the scale width. streak extending from behind the eye to the
Chin and throat uniformly yellow, with few corner of the mouth, running on lower PoO,
faint greyish-brown spots on the infralabials. upper part of SL 6 (ivory yellow bottom) and
centres of SL 7 and 8. These two supralabials
MNHN 1999.9090: In alcohol and life, dor- are pale yellow on their lower part, SL 7 is
sal surfaces are dark greyish-brown above greyish-ochre above, whereas SL 8 is ivory
(DSR 8-10 before VEN 100, 7-9 behind), pale yellow on its upper part which belongs to the
ochre brown on the sides, distinctly paler end of the dorsolateral stripe. The side of the
than on the back, with a conspicuous ivory- neck is ivory yellow above, with a wide
yellow dorsolateral stripe running on DSR blackish brown and continuous stripe in its
5th, 6th and 7th (lower half) (4th, 5th, 6th middle part resulting from the continuity of
respectively behind VEN 100), bordered be- the postocular streak which connects with
low with a well defined, single, blackish- the ochre-brown colour of the lower half of
brown line on upper half of DSR 4 and the body, and is ivory yellow on its lower
extreme lower part of DSR 5, and above by part. Eye black. Venter ivory yellow, with, on
a thinner and fainter irregular blackish- each ventral scale, an elongated small spot
brown line on the extreme upper part of DSR near at about 3/4 of the scale width. Chin and
7 and lower part of DSR 8. The dorsolateral throat uniformly yellow, with few faint grey-
beige yellow stripe extends forwards on the ish-brown spots on the infralabials.
neck and on upper side of the head where it
widens slightly and becomes paler and more
conspicuous behind the upper temporals. Discussion
The lower blackish-brown line widens sig- Comparison with other species
nificantly on the side of the neck and is
connected without constriction to the black We investigated the main morphological si-
postocular streak, whereas the upper dark milarities and differences between Amphies-
171
PATRICK DAVID et al.
ma bitaeniatum, Amphiesma octolineatum 5), already noticed by WALL (1925), is con-
and Amphiesma parallelum, as well as be- firmed. The combination of these two charac-
tween these taxa and the specimens from ters is usually sufficient to distinguish be-
Vietnam. In this preliminary paper, we focus tween the two taxa.
only on characters which allow an immediate (C) Amphiesma bitaeniatum and Am-
identification of the species. Meristic data phiesma octolineatum can be readily distin-
will be presented elsewhere (DAVID et al., in guished by differences in the characters (1),
prep.). As a consequence, we retain here only (2), (3), (4), (6), and (7). The most significant
the following characters: (1) background characters useful to separate these two spe-
dorsal colour; (2) width of a lower black cies are characters (1; see Key), (2) and (3), as
dorsolateral line (bordering the lower margin these lateral stripes are usually fused, or sepa-
of the pale dorsolateral stripe); (3) width of rated by a very thin yellowish line, leading
the black ventrolateral stripe; (4) general to character (4), with the sides much darker
appearance of the sides compared to the than the upper surface of the body in A.
dorsum colour (paler/darker), resulting from octolineatum, (6) and (7), dorsal scales of A.
the width of the lateral black stripes; (5) octolineatum being only weakly keeled
continuity of the postocular streak with the above, and totally smooth on the first DSR,
lower black dorsolateral stripe; (6) KSR; (7) whereas A. bitaeniatum is usually strongly
K1R; (8) DSR notching (describes the apical keeled above, and more or less weakly
part of dorsal scales. Scales can either show keeled on the first DSR, and, lastly, (8), the
the normal, posteriorly pointed rhomboedric dorsal scales of A. octolineatum being nor-
shape, or have the posterior part deeply mal or at best barely notched posteriorly,
notched). Another useful character is (9) den- whereas scales are usually strongly notched
titional morphology: presence or absence of in A. bitaeniatum, especially on the posterior
a diastema between the enlarged posterior part of the body.
maxillary teeth and the anterior series of MALNATE (1960) recognized several infor-
shorter teeth. mal groups and subgroups within the genus
From these preliminary results, it appears Amphiesma, subdivided into subgroups. One
that (see also the key provided below): of them, based on similarities in the general
(A) Both Vietnamese specimens from Sa- dorsal patterns, included Amphiesma paral-
pa and Mt. Phang Si Pang can be referred lelum, Amphiesma bitaeniatum and Am-
with confidence to Amphiesma bitaeniatum. phiesma octolineatum. The great morpho-
(B) Amphiesma bitaeniatum and A. pa- logical similarity between these three spe-
rallelum are readily distinguishable, without cies led to extensive and often intricate
intermediate patterns. They should be con- confusion in the literature. For example,
sidered distinct species, which can be sepa- BOURRET (1936) and SMITH (1943) did not
rated by constant differences in characters regard Amphiesma bitaeniatum as valid and
(4), (5), (7) and (9). The lattermost character, placed it in the synonymy of Amphiesma
the dentitional morphology, and the dorsal parallelum (then known as Natrix paralle-
tone are diagnostic. In A. parallelum, regard- la). Other taxa, such as Natrix clerki WALL,
less of whether the specimens are light or 1925, Amphiesma metusia INGER, ZHAO, SHAF-
dark, the general coloration of body (Charac- FER & WU, 1990 and Tropidonotus parallelus
ter 4) is nearly identical on the back and the sublaevis DESPAX, 1913, currently regarded
side, whereas in A. bitaeniatum, the upper either as valid or as synonyms of one of the
dorsal surfaces are distinctly darker than the three species cited above, need to have their
sides, namely the area below the dorsolateral status re-evaluated. Their status will be dis-
stripe. The significance of the continuity or cussed in a forthcoming paper, along with
discontinuity of the postocular streak with updated definitions, chresonymies and dis-
the lateral black stripe of the body (Character tributions of these species.
172
On the occurrence of Amphiesma bitaeniatum in Vietnam
Distribution Amphiesma sieboldii, as defined by MALNATE
(1966). Only a single, old specimen col-
The presence of Amphiesma bitaeniatum at lected by B. H. HODGSON (BMNH 58.6.24.5)
Sapa and on Mt. Phang Si Pang (formerly and allegedly obtained in Nepal, is indeed an
Fan-si-pan), near the Chinese border, extends Amphiesma parallelum. We consider that
the range of the species eastwards from the KRAMER (1977) was correct in stating that no
previously southernmost confirmed station specimen of Amphiesma parallelum is
of the Chinese province of Yunnan (Xishu- known from Nepal with certainty. The same
angbanna). Amphiesma bitaeniatum has re- misidentification appears in ZHAO et al.
cently been discovered in northern Thailand, (1998: 75), in which the three specimens
on the basis of a specimen depicted in CHAN- cited from Xizang Province (China) as MVZ
ARD et al. (1999) and identified in DAVID & 177474 and MVZ 177672-673 (in fact a
PAUWELS (2000). This specimen (NRCT lapsus calami for CAS 177474, 177672 and
980506), which extends considerably south- 177673) are also referable to Amphiesma
wards the range of Amphiesma bitaeniatum, sieboldii. On the basis of these results, the
will be discussed elsewhere. Amphiesma bi- two records of Amphiesma parallelum from
taeniatum has also recently been collected in northern Vietnam appearing in NGUYÊN & HÔ
the Chinese province of Guangxi (Cenwang- (1996) are referred to Amphiesma bitaenia-
lao Shan, Tianlin County) (ANONYMOUS tum. BOURRET (1939) did not mention Am-
2003). Thanks to the courtesy of MICHAEL W. phiesma parallelum from the montane sta-
LAU, we examined this specimen. Previously, tions of northern Vietnam, so he probably
in China, this species was known only from never encountered any species of the Am-
the province of Yunnan. Its occurrence in phiesma parallelum subgroup there. BOURRET
Guangxi, another province bordering Viet- (1934, 1936) reported Amphiesma paralle-
nam, makes it very likely that it will be lum from Cambodia (as Natrix parallela pa-
discovered in other localities in northern rallela), without precise locality. On the ba-
Vietnam, Laos, and southern China in the sis of his description, these specimens seem
future. to be referable to Amphiesma boulengeri
Amphiesma parallelum is only known (GRESSITT 1937) (DAVID et al., unpublished).
with certainty from north-eastern India The specimen from Nagaland, India
(states of Meghalaya, West Bengal and Aru- (KSC 414) and a specimen from Myanmar
nachal Pradesh), northern Myanmar (north- (BMNH 1940.6.4.29) show some differences
ern Kachin State) and from the People’s Re- in pattern, scalation and dentition, and share
public of China, from where it has been several characters with the holotype of Na-
definitely recorded only in extreme western trix clerki WALL, 1925, which might prove to
Yunnan (CAS 215036). We also examined a be a valid species, in contrast to SMITH’S
typical specimen of Amphiesma bitaeniatum (1943) synonymization with Amphiesma pa-
(CAS 215037) from a nearby locality. Am- rallelum. This problem will be addressed in
phiesma parallelum is the only one of the the next paper.
three species occurring in India, and has yet Lastly, Amphiesma octolineatum is still
to be recorded farther east than extreme west- known only from the People’s Republic of
ern Yunnan. Contrary to information appear- China, in the provinces of Yunnan, southern
ing in several references, including GRUBER Sichuan, Guizhou and Guangxi Zhuang Au-
(2002), Amphiesma parallelum is not defi- tonomous Province (ZHAO et al. 1998). It most
nitely known from Nepal. We examined ma- probably also occurs in Vietnam, Laos and
ny alleged specimens of Amphiesma paral- western Myanmar. The status of several spe-
lelum from Nepal, and all proved to be refer- cimens from western Sichuan identified as
able to the complex Amphiesma platyceps / Amphiesma octolineatum (for example in
173
PATRICK DAVID et al.
ZHAO et al. 1998) will be discussed in DAVID present paper, could not be examined by
& VOGEL (in prep.). The specimens recorded ourselves. The description suggests that the
from Guangxi Zhuang by MO et al. (2002), identification as Amphiesma octolineatum is
collected at the same locality as a specimen correct.
of Amphiesma bitaeniatum examined for the
Key to the species of the parallelum-subgroup
The three species considered above share a grey, greyish-brown, ochre brown or pale brown
background, an overall striped pattern with at least a lighter, more or less distinct, black edged
dorsolateral stripe, and 19-17 DSR. They can be separated, as well as the species Amphiesma
platyceps and A. sieboldii, confused with Amphiesma parallelum, by the combination of the
following characters (characters for A. platyceps and A. sieboldii drawn from MALNATE 1966
and specimens examined by us):
1 a. No dorsolateral stripe, or at best a row of white dots; a narrow, black or dark brown
subocular and postocular streak; posterior maxillary teeth greatly and abruptly
enlarged, twice as long as other maxillary teeth; at least 190 VEN ..........................2
1 b. A distinct, broad, pale and continuous dorsolateral stripe from neck to the end
of tail; a conspicuous, wide black or dark brown postocular streak; posterior
maxillary teeth distinctly enlarged, but less than twice as long as other maxillary
teeth; less than 178 VEN................................................................................................3
2 a. Only upper dorsal scale rows moderately keeled, others smooth; 205-234 VEN
in males, 191-216 VEN in females; dorsal surfaces usually marked with scattered
black dots, without a dorsolateral series of white dots (or barely defined); venter
usually immaculate; subcaudal surfaces usually immaculate, rarely darkened
with grey ..................................................................................... Amphiesma platyceps
2 b. All dorsal scale rows (excepted 1st one) keeled; 191-207 VEN in males, 165-190
VEN in females; dorsal surfaces usually uniformly brown, excepted a dorsola-
teral series of well-defined small white spots; venter often largely speckled with
dark greyish-brown posteriorly; subcaudal surface usually dark
...................................................................................................... Amphiesma sieboldii
3 a. Enlarged posterior maxillary teeth separated from others by a distinct diastema;
body sides and upper dorsal surface of same tone (not paler nor lighter); black
postocular streak separated from lower body lateral black stripe by a gap, or
barely in contact; a black preocular streak on preocular and loreal, sometimes
short or faint, but nearly always present................................. Amphiesma parallelum
3 b. Enlarged maxillary teeth not separated from others by a diastema; sides of body
either distinctly paler or distinctly darker than upper dorsal surface; dark
postocular streak in continuity with lower body lateral black stripe; no black
preocular streak on preocular and loreal ...................................................................... 4
4 a. Dorsal colour brown or ochre-brown; stripe bordered with two narrow black
lines; sides paler than upper body, speckled with black but not marked with a
low lateral black stripe; dorsal scales strongly keeled and deeply notched
posteriorly ............................................................................... Amphiesma bitaeniatum
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On the occurrence of Amphiesma bitaeniatum in Vietnam
4 b. Dorsal colour grey or brownish-grey; stripe bordered below with one or two wide
dark grey or dark brownish-grey stripes, making the side distinctly darker than
upper body; dorsal scales smooth or weakly keeled, not or very slightly
notched........................................................................................................................... 5
5 a. Dorsal colour usually light grey or brownish-grey; dorsolateral stripe ending
anteriorly in narrowing on the nape; stripe bordered with two dark stripes, the
lower one, irregular, very wide; a narrow pale zig-zag-like line on upper part of
DSR 1 ................................................................................... Amphiesma octolineatum
5 b. Dorsal colour grey or blackish-brown; dorsolateral stripe ending anteriorly in
widening on the nape; dark brown or dark brownish-grey on the sides; no zig-
zag line on upper part of DSR 1................................................... Amphiesma metusia
Whereas some specimens, especially Amphiesma optatum (HU & DJAO, 1966),
some of the darker representatives of Am- described from Sichuan and known from sou-
phiesma parallelum and Amphiesma octoli- thern China (ZHAO et al. 1998), was only
neatum, may be slightly different from the recently discovered at Tam Dao, in northern
typical patterns given in this key, the combi- Vietnam (DAVID et al. 1999). It is interesting
nation of all characters allow a rather confi- to note that another Chinese natricine spe-
dent identification, including in long pre- cies, Sinonatrix aequifasciata (BARBOUR,
served animals. 1908), widely distributed in China (ZHAO et
al. 1998), was also recently collected for the
first time in Tam Dao, Vietnam (VOGEL et al.
Conclusions 2004). These discoveries stress the limited
knowledge that we still have on the biodiver-
Ascertaining the limits of the ranges of Am- sity of snakes in southeastern Asia, even in
phiesma parallelum towards east, A. bitaeni- areas comparatively well investigated, such
atum towards west, and A. octolieatum to- as Tam Dao Hill Station.
wards east and south, respectively, requires
the collection of more specimens from North-
ern Myanmar, China and Laos. The occur- Acknowledgements
rence of Amphiesma bitaeniatum in northern
Vietnam raises to eight the number of species We are indebted to AARON M. BAUER (Villanova)
for critically reading the manuscript and his con-
of this genus in this country. According to
the literature (NGUYÊN & HÔ 1996; ORLOV et al. structive comments. We warmly thank NORBERT
BRACHTEL (Mainz) for his enormous help by the
2000) and our data, Vietnam is inhabited by
expeditions to Vietnam. We are grateful to COLIN J.
Amphiesma atemporale (BOURRET, 1934), MCCARTHY (London), ROSAMMA MATHEW (Shil-
Amphiesma bitaeniatum (WALL, 1925), Am- long), S. J. S. HATTAR, (Shillong), YUEZHAO WANG,
phiesma boulengeri (GRESSITT, 1937), Am- SHENGQUAN LI and YUEYING CHEN (Chengdu), and
phiesma craspedogaster (BOULENGER, 1899), JIFAN MA and JIANQIANG CEN (Shanghai), who
Amphiesma khasiense (BOULENGER, 1890), either kindly loaned us or let us examine specimens
Amphiesma optatum (HU & DJAO, 1966), Am- deposited in their collections. We are also grateful
phiesma sauteri bourreti MALNATE, 1962 and to EDMOND V. MALNATE (Philadelphia) for his
precious indications on the genus Amphiesma,
Amphiesma stolatum (LINNAEUS, 1758). We
TANYA CHAN-ARD (Pathum Thani) and MICHAEL W.
have yet to examine any Vietnamese speci-
LAU (Hong Kong) for kindly making available
men of Amphiesma modestum, a species
specimens and unpublished data. We thank XIAO-
widely reported in the literature from north- HUA TU (Paris) for her numerous and helpful trans-
ern Vietnam. lations of Chinese literature.
175
PATRICK DAVID et al.
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