Kapuas Mud Snake, Homalophis gyii (Murphy, Voris, Auliya 2005)
Enhydis doriae - Brown, 1902:180 Proceedings of the National Academy of Science Philadelphia.
Enhydris gyii Murphy, Voris, and Auliya 2005, Raffles Bulletin of Zoology, 53:116
Holotype. – A female, ZFMK 65824 from Indonesia, Kalbar, Sungei Kapuas, near Putussibau (0º49’60”N, 112º55’60”E). Collector: Mark Auliya, November 11, 1996. Paratypes (2). – ZFMK 65825, a female from Indonesia, Kalbar, Sungei Bungut, about 5 hours south of Putussibauna and ANSP 26411 from the Kapuas River, Barat Province, Kalimantan.
Homalophis gyii Murphy and Voris, 2014:23.
Etymology. This snake was named in honor of Ko Ko Gyi, the Burmese herpetologist who studied at the University of Kansas and was the last to review the homalopsid snakes.
Distribution. This species is known only from the Kapuas River drainage in Kalimantan, Indonesia (island of Borneo).
Diagnosis. A snake with 25 - 27 scale rows at mid-body; 15 or 16 upper labials, with the labials below and behind the eye horizontally divided; and subocular scales. Phytolopsis punctata is the only other possibly sympatric homalopsid with 25 - 27 scale rows at mid-body, and it can be immediately separated from that species by the absence of subocular scales. All mainland Southeast Asian homalopsid with 25 - 27 scale rows also lack subocular scales. It is most easily confused with H. doriae, a possible sympatric congener, it can be readily separated from doriae on the basis of mid-body scale rows (doriae has 29 - 33) and a higher ventral scale count (doriae has 137 - 152, range for both sexes), gyii females have 155 - 159. Additionally gyii has 16 - 20 lower labials while doriae has 14 - 18
Size. The largest specimen measured was a female with a total length of 762 mm and a 96 mm tail. I have no data on males, since this species is known from only three females. Three females have tails that are 14 - 18% of the SVL.
External Morphology. The head is distinct from neck, the body is cylindrical, and the posterior body and tail are slightly compressed. The eyes are dorsolateral, and have a round pupil (when preserved); and have a diameter that is slightly less than the greatest diameter of the nasal scale.
On the head the rostral is as tall as it is broad, pentagonal, and has a shallow notch; it is also horizontally divided in the holotype but not in the paratypes; and, it has about the same area as a nasal scale. The nasals are in contact and semi divided with the nasal cleft touching the second labial. The two internasal scales are posterior to the nasals and slightly penetrating; they also contact the loreal scale. ANSP 26411 has the internasal divided into three scales. The prefrontal scales are paired, larger than the internasals, and they contact the loreal scales. The frontal length is less than the interorbital distance. The parietals are slightly longer than the frontal. The loreal scales are single or double; the loreal is larger than the prefrontal scales; and the loreal is contacted by upper labials 2 - 6 or 3 - 5, the latter is the usual condition. There are two or three supraocular scales on each side; the anterior scale is smaller than the posterior scale. Other scales in the ocular ring include three postoculars, one preocular, and one or two subocular scales; the lower preocular scale also extends under the eye and is not included in the subocular count. The temporal formula is usually 1 + 2 + 3, but it maybe 1 + 1 + 2 or 2 + 2 + 3 with the secondary upper temporal scale being the largest. The upper labials are tuberculate and number 15 - 16; upper labials 1 - 4 are tall and narrow and tend to be undivided, labials 5 - 9 are divided into two tiers, labials 10 - 12 are divided into three tiers; at labial 13 the jaw turns upward and forms a right angle.
On the chin the lower labials number 16 - 17; labials 1 - 2 form the mental groove, and lower labials 2 - 5 contact the anterior chin shields; lower labials 1 - 7 are undivided and labials 8 - 9 and beyond are divided and small. There are four pairs of chin shields, the first pair are the largest and are boomerang-shaped. The other pairs are separated by small scales and do not border the mental groove. There are about six gular scales.
On the body the dorsal scales are in 27 rows on the neck, 25 - 27 rows at mid-body, and these rows are reduced to 21 - 22 posteriorly. Scales in row one are slightly taller than those in subsequent rows. The scales are smooth, except for those few scales at mid-body toward the vertebral midline that are tuberculate. The ventral scales are rounded and broad, about 4 - 5 times wider than the height of a nearby dorsal scale; and they number 155 - 159 in the three females examined.
On the tail the subcaudal scales are divided and number 44 - 46 in the three females examined.
Color and Pattern. On scale rows 1 - 4 at mid-body the scales are red with scattered brown pigment, on the remainder of the scale rows each scale has a light colored margin bordered on the inside by brown pigment, with a central irregular red spot; overall the dorsum is a uniform red-brown. This red-brown coloration extends onto the crown of the head and on to the chin (the mental and first 4 - 5 labials), and forms a line on the margin of the lower labials which outlines the upper jaw. The ventral surface of the body is red; the ventral surface of the tail has a braided appearance with a dark anterior spot on each scale and the posterior portion of the scale having a red spot. The posterior upper labials are also red. The scales on this snake are iridescent. Auliya (2003) commented on the apparent ability this species to change color, after a specimen had been placed in a bucket that did not allow light to enter, it was found to be “almost white.”
Note: Of historical interest is the paratype ANSP 26411. This specimen was collected A. E. Brown on the 1897 Harrison-Hiller Expedition, and considered by him to be Enhydris doriae (Brown, 1902). Barbour (1912) and Gyi (1970) apparently examined this same specimen, and both failed to recognize it as distinct from E. doriae. The specimen is now faded from preservatives and light, but when compared to a faded Enhydris doriae it stands out because each scale has a faded cream area in the center, that was red in life, while E. doriae scales fade uniformly. It is also interesting to note that Gyi listed this specimen in material examined, listed its 25 scale rows at mid-body in his Table 6, but failed to comment on the unusual specimen and scale counts in the species account for Enhydris doriae.
Natural History. Very little is known about the habitat, feeding habits, and reproduction of this species. Two specimens were obtained during periods of heavy rainfall in flooded riparian habitats. The wet season in Putussibau may be characterized by months that exceed 400 mm of precipitation (January, February, August, October and November), and a total annual precipitation of 4480 mm (Murphy et al. 2005). While lowland endemicity is frequently considered to be minimal, the Kapaus River drainage has at least one area high in endemicity, the Danau Sentarum Wildlife Reserve is in an area about 700 km upstream in western Kalimantan. The Reserve is west of the type locality and is a large complex of swamp forest, peat swamps, and lakes. This area is subject to two annual monsoons, a northeast monsoon in October, and a second monsoon in March. Water levels in the area recede by August, at which time the floodplain lakes are completely dry for a 3-4 month period, the area then becomes a dry savanna with high daily temperatures. This climatic regime has produced an environment unique from the surrounding lowland forest and a number of endemic fish and bird species are known from this area (Sebastian, 1994). Rasmussen et al. (2001) have recently described the freshwater sea snake Hydrophis sibauensis, (Hydrophiidae), from the Sibua River, just north of the city of Putussibau, very near the type locality of H. gyii.