Monday, July 14, 2014

Rainbow Mud Snake, Enhydris enhydris Schneider, 1799

  
Hydrus enhydris Schneider, 1799 Historiae Amphibiorum, 1:245.  Type locality: "Indiae orientalis;" [Based upon an illustration of Mutta Pam in Russell, Indian Serpents, p. 35, pl. 30, 1796.]

Hydrus atrocaeruleus Shaw, 1802 General Zoology, 3:567, 1802 [Based upon an illustration of Mutta Pam, in Russell, Indian Serpents, p. 35, pl. 30, 1796.]

Enhydris caerulea Sonni and Latreille, 1801 Histoire naturelle des reptiles, 4:202, 1801 [Based upon an illustration of Mutta Pam in Russell, Indian Serpents, p. 35, pl. 30, 1796.]

Coluber pythonissa Daudin, 1803d Histoire naturelle…des reptiles…de Buffon, rédigée par           Sonnini, 7:202, [Based upon an illustration of "Mutta Pam" Russell, Indian Serpents, p. 35, pl.         30, 1796.]

Homalopsis aer Boie, 1826b Isis von Oken, column 214. Type locality: "Java." Holotype: Paris Museum. Collector: M. Oppel.

Potamophis lusingtonii Cantor, 1836 Transactions of the Medical and Physical Society 7:139. Type locality: India.

Coluber aer - Eydoux and Gervais, 1837 Magasin de Zoologie Journal, 3, pl. 16, figures 2-3.

Homalopsis olivaceus Cantor, 1839 Proceedings of the Zoological Society of London, p. 55. Type locality: Bengal. Holotype: based upon a colored sketch in Bodleian Library.

Hypsirhina trilineata Gray, 1842 Zoological Miscellany p. 66. Type locality: "China." Holotype: BMNH 1946.1.7.22. [The type is a female with 21 scale rows at midbody. The bottle also bears the following information “Ular Aer, Hypsirhina aer, India, 111.25.3.b.”]

Hypsirhina furcata Gray 1842 Zoological Miscellany, p. 66. Type locality: "India." Syntypes: BMNH 1946.1.21.67-68. [The syntypes are two neonates with 21 scale rows at midbody, and are un-remarkable.]

Hypsirhina bilineata Gray 1842 Zoological Miscellany, p. 66. Type locality: "China." Holotype: BMNH 1946.1.5.31. [This is a male Enhydris enhydris with 21 scale rows at midbody.]

Hypsirhina aer - Gray 1849 Catalogue of the Specimens of Snakes in the Collection of the British Museum, p. 72.

Homalopsis enhydris -  Cantor, 1847 Catalogue Malay Reptiles, p. 99.

Hypsirhina enhydris - Duméril, Bibron, and Duméril, 1854 Érpétologie Générale...Reptiles, 7:946

Hypsirhina albolineata Morice, 1875c Coup d'Oeil sur la Fauna de la Cochinchine Francaise, p. 58. Type locality: Vietnam. Syntypes: MHNL 42000343(2). The syntypes are two neonate specimens bleached white from light and chemicals, both are females and have 21 scale rows at midbody.

Hypsirhina enhydris bilineata – Lampe and Lindholm, 1902 Jahrbuch des Nassauischen Vereins für Naturkunde, 55:31.

Helicops indicus Annandale, 1905 Journal of the Asiatic Society of Bengal, p. 211. Type locality: Bengal. Holotype: Calcutta Museum.

Enhydris enhydris - Barbour, 1912 Memoires of the Museum of Comparative Zoology 44(1):122.

Etymology: Like the genus, this species is named for its highly aquatic life style; enhydris is Greek for water snake.

Common Names: Wall (1912) wrote about the history of the common names for this taxon.

Our first introduction to H. enhydris is through Russell who under the name "Mutta pam" figured and remarked upon a specimen in 1796 which had been captured in an Eel trap in the Lake of Ankapilly (North of the Godavery, near Vizagapatam). Three years later Schneider alluded to it in his History of Amphibians, under the name Hydrus enhydris....Schneider's Water Snake suggests itself, reserving Russell's name to designate the other common water snake alluded to by him and to which Schneider also stands as godfather. I refer to Cerberus rhynchops....

             The names mentioned by Russell are the only ones known to me in India. These "Mutta pam," mud snake, and "Ally pam" are presumably in use in the Vizagapatam District. In most places in India I expect it would come under that very comprehensive title "pani ka samp." Günther mentions "oular ayer" as the name by which it is known to the natives in Java, and Flower says – ‘In Siam it is called ‘Ngu‑pla’’ or fish snake, in common with other homalopsids.

            Later, Wall (1924) called it “Schneider's Water Snake.” Gharpurey (1944) undoubtedly drawing on Walls’ comments wrote, "On the east coast round about Vizagapatam it is called Mutta pam or Ally pam, which means a mud snake." And, in his account he calls it "Schneider's Water Snake." Whitaker (1978) reported its English name in India as the “Common Smooth Water Snake.”
            Das (1998) listed the common names for this species in five different Indian languages. Assamese: Meni (=cow/buffalo [feminine], possibly in allusion to innocence [for being non-venomous]. Bengali: Huria (=?); Kanametuli (=blind earth dweller); Paina shap (=water snake). Nepali: Mach giddhee (= fish brain). Tamil: Alai pambu (= surf snake); Mutta pambu (=egg snake). Telugu: Ally pam (=wave snake); Mutta pam (=egg snake). These names were used in Russell’s Indian Serpents p. 35, plate 30. Shrestha (2001) stated that “Dhod” is the common name in Nepal. Hoesel (1959) reported that the English name for this species in Java is “Fish Snapper”. And, Hindley (1988) called this snake the “Rainbow Water Snake.”

Distribution
            Enhydris enhydris ranges from Nepal, northeast peninsular India and an apparent isolated population in Sri Lanka, eastward throughout Bangladesh and Myanmar, across the Indochinese peninsula, and southward into Indonesia from Sumatra to Sulawesi.
            A discussion of questionable localities follows. Its presence in Nepal was noted by Shrestha (2001), who wrote, “It is common in the ponds, sluggish waters and the irrigated fields of mountainous areas of Nepal.” I have not seen any specimens from Nepal to date but its presence in lowland areas seems probable. Rooij (1917) and Haas (1950) report this snake from New Guinea, these are most certainly misidentified Enhydris polylepis. Gyi (1970) does not mention Ceylon [=Sri Lanka] in his distribution, but in his materials examined list stated that CAS 12767 is from Ceylon with no specific locality. This supports Ambercrombie’s (1913) Jaffa Province record, which Wall (1921) apparently over looked completely and it has been over looked by more recent Sri Lankan herpetologists. My examination of the Sri Lankan CAS specimen found it to be an unremarkable specimen of Enhydris enhydris. Several authors (Sclater, 1891a, deRooj, 1917, Pope, 1935) state E. enhydris is in China. Zhao and Adler (1993) have not listed it from China, noting that a Hong Kong specimen was suspected of being from Thailand (Romer, 1961) and that recent workers have failed to find it in Hong Kong (Karsen et al., 1986). Romer’s comments were based upon BMNH 1956.1.12.93, a specimen apparently found on a ship that had come from Bangkok. There was, however, a second Hong Kong specimen (BMNH 56.11.17.58) presented to the BMNH by J. C. Bowring, and Wall (1924) considered it present in China’s southern provinces and continental islands. Additionally, the species is known to occur in North Vietnam, thus the likelihood of its presence in tropical southern China cannot be easily dismissed. Also of interest is its status in Laos, Deuve (1970) considered it present but given the scale counts and illustrations his description of E. enhydris is based entirely on Enhydris subtaeniata (the sister species to Enhydris enhydris, see the subtaeniata account). Thus, it may be present in Laos and southern China but documentation is absent, similarly its presence in Nepal and Sri Lanka are in need of further examination. Iskandar and Nio (1996) consider the Sulawesi population to be introduced since it is found in the vicinity of just a few towns.

Diagnosis: A fresh water snake with 21 scale rows at midbody; 153 - 174 ventral scales; a relatively long tail; a pattern of longitudinal stripes, with no lateral or dorsal spots or bars; and a remarkably small, narrow head. The internasal is single and contacts the loreal, and there are two pairs of chin shields with the second pair longer than the first. The snake that it may be most easily confused with is its sympatric (in the Mekong drainage) sister species, Enhydris subtaeniata. E. subtaeniata has fewer than 153 ventral scales; a pattern of spots on scale rows 4 - 6; and two or three pairs of chin shields, when there are two pairs the first pair is longer than the second pair. Enhydris bennettii also has 21 scale rows but its internasal does not make contact with the loreal; the same is true for E. chinensis which has 23 rows of scales at midbody. Enhydris jagorii, E. longicauda, E. innominata, and E. chanardi also are sympatric with this species in the Indochinese peninsula and all have 21 scale rows at midbody. However, these species lack a dorsal pattern of longitudinal stripes, have fewer than 153 ventral scales, and have extremely ovate, smooth scales lacking striations (enhydris and subtaeniata have smooth scales with striations).

Size: The largest female measured had a total length of 882 mm with a 148 mm tail. The largest male measured had a total length of 700 mm and a 125 mm tail, both of these specimens came from the vicinity of Kabin Buri, in eastern Thailand. Adult females tend to be larger and more robust than males. There may be considerable size differences between populations. The Ban Tha Hin, Lake Songkhla population in southern Thailand was composed of snakes that were relatively small (n = 18 females, = 426, r = 375 - 509) compared to the few snakes obtained at a site near Satun, Thailand. The population in Tonlé Sap, Cambodia contains very large individuals overall (n = 32 females, = 538, r = 422 - 644), see Murphy et al. (2002). Karns et al. (2005) reported on populations of E. enhydris in central Thailand. The population at Ban Badan in the Khorat Basin showed no sexual dimorphism in body size, while the coastal plain population at Kabin Buri showed size sexual dimorphism.  Literature comments about body size in this species support the idea that body size varies between populations. In Java, Hoesel (1959) considers its average length to be about 50 cm. Wall (1924) reported a second-hand record from a Captain Frere in a private letter dated July 1911; the snake was from Minbu, Burma and was said to be 972 mm (?total length). Schleich and Kästle (2002) report females up to 96 cm and this length may be based upon Wall’s comment. Saint Girons (1972) also reported an exceptionally large female (880 mm) from Tonlé Sap, Cambodia. Based upon measurements of two litters (n = 15) born to snakes obtained in a Bangkok market, neonates ranged in size from 143 - 162 mm SVL (= 155 mm).  This is about twice the size of the young reported by Batchelor (1958) who stated neonates were about three inches (76.2 mm). Tails in males tend to be longer than in females, but in some populations there is considerable overlap, see Table 9. The smallest specimens measured were the syntypes of Hypsirhina albolineata that had SVLs of 131 and 133 mm with 39 and 40 mm tails respectively. Karns et al. (2005) measured 47 neonates that were born in captivity, and had been held for several days. All were from Kabin Buri, Thailand and had a mean SVL of 17.8 cm (r = 15.8-20.2) and a mean mass of 3.1 g (r = 2.7 - 5.0).

External Morphology
            The head is small and slightly depressed. The body is cylindrical to slightly depressed. The eyes are dorsolateral, but slightly more lateral than some other species. The orbit diameter is equal to, or greater than the width of the frontal.
            On the head the rostral scale is pentagonal and is about twice as wide as tall, it is barely visible from above, and it and the other head scales are finely tuberculate. The nasals are in contact; each having a diameter that is less than the diameter of the eye, and the nasals are semi-divided with the cleft touching to the first labial. The internasal is usually single, slightly penetrating the nasals, and about twice as wide as long. The prefrontal scales are in contact with the loreal and preocular; they are slightly larger than the loreal, but less than the diameter of the eye. The frontal is about twice as long as wide and about equal in length to the parietal. The loreal is usually longer than tall and in contact with the first three labials. The supraocular is single and the anterior portion is narrower than the posterior portion; the preocular is single and taller than long; and there are two postocular scales, with the bottom scale extending slightly under the orbit. There are no subocular scales; the fourth upper labial enters the orbit. The temporal formula is 1 + 2 + 3, and all temporal scales are just slightly enlarged, the secondary and tertiary temporal scales are difficult to distinguish from the occipitals. Upper labials number 7 - 8, usually eight.
            On the chin lower labials number 9 - 10, usually 10 (Gyi gives a range of 10 - 12). The first three (rarely four) are in contact with the anterior pair of chin shields. The second pair of chin shields is longer than the first, but the first pair is broader than the second pair. The second pair of chin shields is separated by a small pair of scales. Two specimens from Myanmar and one specimen from Cambodia have three chin shields on one side and two on the other. Males appear to have more numerous tubercles on these scales than females. On females the tubercles appear to be few and restricted to the margins of scales. Gular scales number 9 - 11.
            On the body the dorsal scales on the neck are in 23 - 27 rows. The highest scale counts (25 -27) on the neck come from specimens on the eastern edge of the range (India and Myanmar). Striations are present on the dorsal scales of this species and tubercles are present in some males. Dorsal scales at midbody are in 21 rows, although four specimens (otherwise unremarkable) from Myanmar have 23 rows. The scales are ovate and become only elongate toward the midline and striations are present. Dorsal scales near the vent are in 17 - 21 rows. They are ovate and become slightly more elongate toward the midline, and they are striated. The ventral scales at anterior body are about 2.5 times the height of a nearby dorsal, at midbody they are about four times the height of a nearby dorsal scale, and at posterior body they are about three times the height of a dorsal scale. Ventral scales number 153 - 174 in males and 153 - 170 in females, one aberrant specimen from Myanmar (KU 92480) has 126. The anal plate is divided and about the same length as the preceding ventral.
            On the tail the subcaudal scales are divided and number 64 - 83 in males and 57 - 76 in females. Dorsal tail scales are ovate and striated. Males have a slight constriction at the base of the tail, and their tails are also longer than female tails. It is interesting to note that when all populations are combined the subcaudal scale counts for females overlap males. However, when individual populations are examined the sexual dimorphism of higher counts in males becomes quite distinct in each population examined. The notable exception being India. The Cambodia population has the longest tails of the populations examined. At the base of the tail the width is 81% of the height, based on the average of five specimens.
            Color and pattern. The head is a uniform brown-gray with yellow upper labials. There is an indistinct nape stripe. There is a dark stripe on the edge of the ventral scales and the first scale row, most of the first scale row, all of the second, and the bottom part of the third are yellow to cream. All scale rows above the third are dark gray-brown. A dark mid-dorsal stripe is present in some specimens, on scale rows 8 - 12.  Other specimens may have a red dorsolateral stripe on each side of the midline.  The belly is usually cream with a faint midline stripe and the edge stripes already noted. However, some specimens may have a uniform red belly that extends onto the first two scale rows, and others may have a dark blotch on each ventral scale. The ventral side of the tail has a midline stripe and lateral stripes also. While examining large numbers of specimens from southern Thailand, central Thailand, and Tonlé Sap, Cambodia it became apparent that the Cambodia population showed the greatest diversity in color and pattern.
            Karyotype. Sharma et al. (1980) reported a 2N chromosome number of 36.

Habitat
            This highly aquatic snake uses a variety of stagnant and slow moving aquatic habitats ranging from rice paddy, canals, and ditches to lakes and rivers. It uses relatively shallow freshwater environments with muddy substrates and can be found in and around urban areas, it seems to thrive in disturbed habitats. I have found this snake dead on the road next to drainage tiles containing water on university campuses in metropolitan areas such as Bangkok and Khon Kaen Thailand, suggesting that it occasionally leaves the water. This agrees well with the literature on this species. Wall (1912) wrote, "...thoroughly aquatic in habit, as might be inferred from the character, and position of its nostrils. It frequents rivers, estuaries, lakes and marshy ground, even being found according to Cantor in irrigated fields." However, Acharji and Mukherjee (1966) may have confused this species with Cerberus when they wrote, "It was found to feed on mud fishes which crawled on mudflats during ebb tides." Laidlaw (1901) commented that one was found on Gunong Inas (Malaysia) far from the river, it seems likely that it may have followed a small stream to this locality, or was transported there by recent flooding.
            Murphy et al. (1999) and Karns et al. (2000) used trapping, radiotelemetry, and mark-recapture techniques to study this species in a wetland on the edge of Lake Songkhla, Thailand. The wet meadow was dominated by the aquatic grass Paspalum vaginatum, and the study area contained numerous small pools, ditches and canals, which included anthropogenic features including ditches and fish enclosures. This species used edge habitat which was predominately the mud-root tangle and its water interface at the edges of canals (39.2% of telemetric locations) and fish enclosures (28.8% of telemetric locations). Other areas used included wet meadow pools, lake shore, and ditches in the nearby town. Daily movements were usually short distances (< 10 m), punctuated by longer movements of distances up to 350 m over a 24 hour period. There was no significant difference between the movements of males and females. Enhydris enhydris is a thermoconformer; it does not bask to raise its body temperature. Instead it stays within the thermal envelope of the environment, snake body temperatures stayed within the thermal minimums and maximums of the microhabitats they use, and their body temperature showed little variation from 30°C (Figure 3).  Neonates were rarely caught in traps; but they were found in the mud-root tangle, near the water, but not at the mud-water interface where the adults were commonly trapped. Use of this microhabitat by these small snakes may allow them to avoid aquatic predators such as large fish.
            The success of E. enhydris in disturbed environments and its more or less uniform morphology across its broad geographic range suggest this species may have expanded its range recently, and this expansion may have been assisted by humans as they developed rice cultivation and sophisticated water management systems to flood rice paddies.

Diet and Feeding Behavior
            Fish are the primary food of E. enhydris, and specimens examined during this study contained only fish: Rasbora sumatrana, Trichopsis vitta, and Trichogaster trichopterus (Murphy et al., 1999; Voris and Murphy, 2002).  In central Thailand’s Kabin Buri area Karns et al. (2005) dissected 141 E. enhydris (63 males; 78 females) that had died in gill nets as by-catch, 26 (22 females; 4 males) contained prey. All stomach contents were fish, and two reproductive females contained food.  The literature supports the piscivorous diet. Mueller (1887) reported a fish, possibly Anabas, from a specimen from Java. Saint Girons (1972) found only fishes in the specimens he examined. And, Taylor and Elbele (1958) wrote, "The stomach contained eight small fish and parts of others."  Hoesel (1959) wrote it, “…is a skilled catcher of fish, so it is often found amoung the catch of fish traps. In spite of its nocturnal character, many are seen hunting the fish in full day-time. Mostly it clings to some hold with its tail, the curved body in readiness for snapping the passing fish.”  Murphy et al. (1999) reported that this species will sometimes seize fish larger than it can swallow, and report one moving about 1.5 m with a three-spot gourami, Trichogaster trichopterus in its mouth. Small fish are the usual prey, and it is not uncommon to find multiple prey items in a single snake. Several specimens from Tonlé Sap, Cambodia contained multiple specimens of a fish that appeared to belong to the genus Parambassis (Chandidae). The largest fish take from an E. enhydris was an Anabas (Anabantidae) that was 17.3% of the snake’s mass.    
            Smith (1914b) wrote, “It appears to subsist chiefly on fish, but Mr. Herbert informs me that he once caught one which disgorged a skink Mabuia, a very unusual meal, I should think, for this snake." Given the overwhelming amount of evidence that this species feeds almost exclusively on fish the presence of a lizard in its diet is highly questionable. In his 1943 book Smith reported this lizard-eating as if it was his observation; it seems likely the snake that contained the lizard was misidentified. However, there are sympatric aquatic skinks (Tropidophorus) and it is not impossible that they may be taken as prey.

Reproduction
            Dates and observations for copulation in homalopsid snakes are rare; there is an anecdotal account for this species. Wall and Evans (1901) wrote about this species in Myanmar, “These were discovered ‘in copula’ on the 16th November…they were in swampy ground, some distance (about a quarter mile) from a creek, and three miles from the Hlaing river, (tidal).” However, Wall (1912) later gave the date as 16 October 1899. Fishermen at Lake Songkhla in southern Thailand told us about seeing this snake in “balls” at night, presumably referring to mating aggregations, but the behavior was not verified.
            St. Girons and Pfeffer (1971) and St. Girons (1972) also reported on the Tonlé Sap, Cambodia population. Their Table 1 and Figure 19 in the 1971 paper suggested two reproductive seasons per year.  According to this scenario females are in vitellogenesis from early-December to mid-February, they carry out gestation from mid-Feb to late April and parturition occurs in early May.  During a second season, vitellogenesis occurs from mid-June to mid-September, gestation occurs from mid-September to mid-November, and parturition occurs in late-November.
            One hundred and thirteen females from three populations (Cambodia, Myanmar, and Thailand) were examined by Murphy et al. (2002) for eggs and embryos. The Cambodia sample contained 32 females with (= 564 mm SVL) eggs or embryos 6 - 39 (= 20.3). Eight females from Myanmar (= 428 mm SVL) had 5 - 16 (= 7.8) eggs or embryos. Eighteen females from Thailand (= 426mm SVL) had 5 - 16 eggs or embryos (= 8.1). On average the gravid females from Cambodia were larger in body size, clutch size, and relative clutch mass than female snakes from Thailand and Myanmar. And, clutch size was significantly correlated with female body size. They hypothesized that the larger females and clutch sizes in the Cambodian population were due to over-fishing of Tonlé Sap, the source of the snakes. Over-fishing would have reduced the number of large fish (potential snake and small fish predators) and allowed small fish (snake prey) species to become more abundant. The smallest gravid female they reported was 298 mm SVL.
            Karns et al. (2005) found 25 of 78 (32.1%) females from Kabin Buri, Thailand in reproductive condition. The average litter size was 11.0 (r = 2 - 20, n = 22). The mean gravid female was 56.8 mm (r = 43.6 - 69.8). The meanmass of gravid females was 164.5 g (r = 94 - 250.0). They found a significant relationship between female SVL and litter size.
                        Some populations of this species appear to have seasonal reproduction (Tonlé Sap, Cambodia), while others appear to be totally aseasonal (central Thailand). Thus, this species offers a unique opportunity to investigate how local conditions impact reproduction. During the field studies at Lake Songkhla, Thailand many snakes were handled, during data collection (in June and July). After females had been handled, males that were picked up would often vibrate their bodies, probably in response to the pheromones left by the females on the hands of the researchers.  

Predators and Parasites
            Stuart et al. (2000) found Enhydris enhydris composed about 80% of the snake harvest at Tonlé Sap Cambodia. Six years later, Brooks et al. (this volume) report that it is about 72% of the catch. While most of the snakes are sold for crocodile food, gravid females of this species had their ova removed for human consumption. This species is also exploited in southern Vietnam (Stuart, 2004). Lilly (1993) reported this species was involved in the wildlife trade in Indonesia. Liong (1954) described a captive Enhydris enhydris being eaten by the krait Bungarus candidus. Nandi (1984) observed a bandicoot rat, Bandicota inidca, seizing an Enhydris enhydris along a flooded roadside ditch. Wall (1912) reported numerous nematodes in the stomach of a specimen from Behar. Nematodes were abundant in the stomachs of virtually every Thailand specimen examined. The Thai specimens often had so many worms that the specimen appeared to contain prey, but when the stomach was examined, only a bolus of worms was found. However, Cambodian specimens examined completely lacked the worms.

Population and Abundance
            This snake reaches spectacular population densities in shallow, open wetlands with submergent-emergent vegetation at such places as Lake Songkhla in southern Thailand, Kabin Buri in eastern Thailand, and at Tonlé Sap, Cambodia. In these localities this species dominates the aquatic snake assemblages with dense populations. The literature comments cited in the habitat section of this account all suggest that this species is relative common at certain locations and are similar to Cochran’s (1930) impression that it is common in Bangkok. Murphy et al. (1999) marked a total of 235 snakes with PIT tags near the village of Ban Tha Hin, on the edge of Lake Songkhla, a Thailand study site. A total of 380 snakes were captured with 144 recaptures. The results suggested 406 - 567 snakes were present on the study site, and because these snakes use edge habitat they estimate that the density was about one snake per two meters of shore line.
            The localities that have dense populations of this snake (Lake Songkhla, Thailand; Kabin Buri, Thailand; Tonlé Sap, Cambodia) are lowland locations that have become freshwater habitats relatively recently. Lake Songkhla was an ocean bay 200 years ago and it undergoes salt water intrusions and is heavily fished. The other localities were inundated with sea water within the last 6000 years and are also heavily impacted by the fishing industry and other human activities. Thus it appears that E. enhydris may be a disturbed habitat/early successional stage specialist. It is entirely possible that as aquatic ecosystems mature that these populations will undergo natural declines and stabilize at a much lower level.

Venom
            Apparently bites from this snake may be a problem for humans. Acharji and Mukherjee (1966) stated that E. enhydris occasionally inflicts very painful bites. And, D'Abreu (1912) described the following incident of a human bite.

 The subject, a healthy man of about 36, while attempting to catch the snake, which had previously been irritated, was bitten on the back of the right hand between the thumb and the forefinger. There were two distinct punctures and the parts got inflamed at once though scarcely two drops of blood were shed. Fifteen minutes later the hand began to throb and the throbbing lasted for about an hour, after which no ill effects were felt. The snake was a little over a foot in length, and the place of occurrence was Parbatipur, Bengal.

            Several hundreds of these snakes were handled during our work at Lake Songkhla and Kabin Buri in Thailand and rarely did they attempt to bite, and when they did there was no envenomation.

Natural History

  Little is known about the habitat of this species. Most of the specimens appear to have come from the immediate vicinity of Bangkok, one of the largest and rapidly growing cities in Southeast Asia. Undoubtedly much of its original habitat has been altered and its continued existence in the city is problematical. However, Bangkok is built on a river delta, and it still contains many canals that support fish, amphibian, and reptile populations. Thus, its survival seems possible.  USNM 83431 is a female with 13 well developed embryos. All embryos are in Zehr’s stage 36 (hemipenes everted). The litter weighs 39.0g.
           


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