Hypsirhina jagorii – Günther, 1864, The Reptiles of British India, p. 282.
Enhydris jagorii - Smith, 1943, The Fauna of British India…. Reptilia and Amphibia 3:384 (in part).
Enhydris chanardi Murphy and Voris, 2005 Raffles Bulletin Zoology
53:144. Type Locality: Bangkok, Thailand. Holotype: USNM 67516, a female
collected 1 May 1928 in Bangkok (13°45’0N 100°31’0E), Thailand Collector: Hugh
B. Smith.
Etymology
This snake was named in honor of Thai
herpetologist and Bangkok resident Tanya Chan-ard.
Distribution
All specimens of this
snake come from metropolitan Bangkok or the surrounding area. Locality data
often includes comments like, “rice fields of Bangkok” (CAS135735), “near
Bangkok” (UMMZ65336), or “purchased in Bangkok market,” (LSUMZ 16922). Flower (1899) obtained three specimens in Bangkok
and one (BMNH 97.10.8.28) at “Takhamen.” I have been unable to locate a place
with this name in Thailand, but there is a Ta Kam (13°37’60N 100°27’0E) (also
spelled Takam) just west of Bangkok. Another
specimen was collected by H. B. Smith at Ban Pan on the Sikuk (or Sikut River)
I have been unsuccessful in locating this village and river. A specimen
that came from some distance from Bangkok is BMNH 1987.1748, from Chanthaburi
(12°35’60N 10°29’0E). This location is in the Coastal Ranges to the southeast
of Bangkok and suggests the species may be more widespread than the immediate
Bangkok metropolitan area. It is also of interest because this specimen has the
lowest ventral scale count and subcaudal count of any of the specimens
examined. Enhydris chanardi is
endemic (or a near endemic) to the Chao Phraya freshwater swamp forest of the
Indochina Bioregion of Wikramanayake et al. (2002).
Diagnosis
Enhydris chanardi can be distinguished from all other Enhydris with 21 scale rows at midbody
by the combination of the following characteristics: 116 - 125 ventral scales,
41 - 60 subcadual scales (53 - 60 in males and 38 - 49 in females); two pairs
of chin shields with the second pair being the longest or equal to the first
pair; an interocular
distance that is greater than the length of the frontal; scales that are longer
than tall on rows 7 - 15; lateral spots on rows 4 - 5 or 4 - 6; and a stripe on
scale row three. Dorsal scales of this
species lack the striations found in E. enhydris and E. subtaeniata;
the ventral count will also separate this species from E. enhydris, and E.
subtaeniata. The 21 - 23 rows of dorsal scales on the neck, the stripe on
the outer edges of each ventral and scale rows 1 - 3 will distinguish it from Enhydris innominata, E. longicauda, and Enhydris jagorii (includes E. smithii), as will the long second pair of chin shields. The scale
counts on this species are extremely close to those of the sympatric Enhydris jagorii; the color patterns of
these two species are quite distinct and head shapes (jagorii has a narrow, rounded snout, while chanardi’s snout is broad and square), and chanardi has 21 - 23 (usually 21 or 22) dorsal scale rows on the
neck, while jagorii has 23 - 25 scale
rows on the neck. Additionally, E.
jagorii has a frontal that is equal to the length of the parietal, while chanardi has a frontal that is shorter
than the parietal scales.
Size: The
largest specimen measured was a female with a total length of 547 mm, and a 101
mm tail. The largest male was 524 mm in total length with an 87 mm tail. The
other specimens examined were 270 - 380 mm SVL; with 72 - 96 mm tails (the
smallest individual has a broken tail). The tail is 19 - 26% of the SVL in
females, and 26 - 30% of the SVL in males.
External Morphology
The
head is depressed and distinct from the neck. The body is cylindrical at midbody
and becomes strongly compressed posteriorly. The tail is also strongly
compressed.
On
the head the rostral scale is pentagonal and 1.8 times broader than tall. Divided or semi-divided nasals have a cleft touching first
labial and the internasal in most specimens, and only the first labial when it
is semi-divided. Each nasal is slightly larger than the eye’s diameter. The
internasal is posterior to and slightly penetrating the nasals. The internasal
is as broad as the supraocular is long, and contacts the loreal in all of the
specimens examined. The prefrontal scale is divided and in
contact with the loreal and preocular, and has a diameter slightly less than
that of the eye. The supraocular is single and about equal in length to the
width of the internasal; the preocular is single; the postoculars number two,
with the dorsal scale slightly larger than the ventral scale. There is no subocular;
the fourth upper labial enters the orbit. The frontal is
about equal in length to the interocular distance. Upper labial scales number
eight (rarely nine), and are not divided, the fourth enters the orbit, and 1 - 3
contact the loreal. The largest (tallest) upper labial is number six. The
temporal formula is 1 + 2 + 4 or 1 + 2 + 3. The primary temporal is slightly
broader than tall. The secondary temporal scales number two and the upper scale
is larger than the bottom scale. See Figure 26.
On
the chin the lower labials number 10 - 12, the first four or five contact the
anterior chin shield. The largest lower labial is number six or seven. The
labial immediately posterior to the largest labial is elongate, but narrow.
There are two pair of chin shields, with the two pairs about equal in length,
or the second pair is slightly longer than the first, but the first pair is
larger in area and flared or petal-shaped. The first four
or five labials touch the first pair of chin shields.
On
the body the dorsal scale rows number 20 - 23 on the neck (usually 21) and 21
at mid-body, and may be reduced to 19 posteriorly, or remain at 20 or 21 rows.
The scales in the first row are about 20% larger than the scales in the second
row. The dorsal scales in the lower rows (1 - 3 or 1 - 4) particularly towards
the posterior of the body are very ovate; these become
more lanceolate toward the vertebral line. The ventral
scales are wide, about 3 times the height of a nearby dorsal scale, and they
number 110 - 122 in males and 116 - 125 in females. Subcaudal scales number 53 -
60 in males and 41 - 51 in females. However, one male from Chanthaburi has 44
subcaudal scales suggesting that females from this population may have a lower
numbers of subcaudal scales than those from the populations sampled above.