Enhydris gyii, Murphy & Voris & Auliya, 2005

Murphy, John C., Voris, Harold K. & Auliya, Mark, 2005, A New Species Of Enhydris (Serpentes: Colubridae: Homalopsinae) From The Kapuas River System, West Kalimantan, Indonesia, Raffles Bulletin of Zoology 53 (2), pp. 271-275 : 272-274

Enhydris gyii , new species

( Figs. 1-3 )

Hypsirhina doriae – Brown, 1902: 180.

Enhydris doriae – Barbour, 1912: 123; Gyi, 1970: 130; Auliya, 2003: 221.

Material examined. – Holotype – Female, Indonesia, Kalimantan Barat, Sungai Kapuas at Putussibau (0º52'N 112º55'E), where the Sibau River empties into the Kapuas River , Kapuas Hulu Regency, West Kalimantan, coll. Mark Auliya, 27 Oct.1996 ( ZFMK 65824 ).

Paratypes – a female from Indonesia, near Nanga Bunut, where Sungai Bunut empties into the Kapuas River, approximately 106 km downstream the Kapuas River from Putussibau; Kapuas Hulu Regency, West Kalimantan, coll. Mark Auliya, 9 Dec.1996 ( ZFMK 65825 ,); a female from an unknown location along the Kapuas River , West Kalimantan ( ANSP 26411 ) .

Diagnosis. – Enhydris gyii is readily distinguished from all

other Borneo Enhydris by the presence of subocular scales, 25-27 scale rows at midbody, and red-brown dorsal coloration. Each dorsal scale in the rows above row four contain a central red area surrounded by a perimeter of graybrown pigment. Red pigment also occurs on dorsal scale rows 1-4, and the chin and anterior upper labials are also red-brown. Females have 155-159 ventral scales, two preocular scales, temporal scales that are plate-like ( Fig. 1a ) and distinct in the primary and secondary rows. Additionally, the head of females tends to be broad and rounded when viewed from above. In contrast, Enhydris doriae , a sympatric congener, has 29-31 scale rows at midbody, is gray to black above, with red ventral pigment extending on to scale rows 1-5, 1-6, or 1-7 at midbody; its scales lack a central red spot, it has 137- 152 ventral scales (137-152 in females and 139-145 in males); one preocular scale; and the temporal scales tend to be small ( Figure 1b ), and similar to the occipital scales in size, particularly in the secondary and tertiary rows. The head of female E. doriae , of about equal size to E. gyii , tends to be narrower, with a squared-off snout when viewed from above. The other Bornean Enhydris with 25-27 scale rows at mid body is Enhydris punctata but it lacks the red pigmentation and the subocular scales, and has two pairs of chin shields with the anterior pair flared ( E. gyii and E. doriae have 3 or 4 elongated or boomerang-shaped chin shields). Table 1 compares the three species of Bornean Enhydris with 25 or more scale rows at mid body in more detail.

Description of holotype. – The head distinct from neck, the body cylindrical, the posterior body and tail slightly compressed. Body 665 mm long, tail 101 mm, total length 766 mm ( Fig. 2 ). The rostral tall as broad, pentagonal, and with shallow notch; it is also horizontally divided; and, has about the same area as a nasal scale. Nasals in contact and semi-divided, nasal cleft contacts the second labial. Two internasal scales are posterior to the nasals and slightly penetrating; they also contact the loreal scale. Prefrontal scales paired, larger than internasals, and contact the loreals. Frontal length less than the interorbital distance. Parietals slightly longer than the frontal ( Fig. 3a ). Loreal scales are 1/1 and larger than the prefrontal scales. On left the loreal contacted by upper labials 3-5, on right side it contacts labials 2-6. Two supraocular scales on each side; anterior scale smaller than posterior scale. Postocular scales number 3/3, preocular scales 1/1, subocular scales 2/2. Lower preocular scale extends under the eye and not included in subocular count. Eyes are dorsolateral, pupil round, with a diameter slightly less than greatest diameter of nasal scale. Diameter of the orbit less than eye-mouth distance. Right temporal formula 1:2:3, left temporal formula 1:1:2, secondary temporal scale(s) largest. Upper labials tuberculate, number 15 on both sides; on right side upper labials 1-4 tall, narrow, and undivided; labials 5- 9 divided into two tiers; labials 10-12 divided into three tiers; at labial 13 the jaw turns upward and forms a right angle; on left side labials 1-4 undivided; 5-10 divided into two tiers, 11-12 divided into three tiers ( Fig. 3b ). Lower labials number 17/16; labials 1-2 form mental groove, and lower labials 2- 5 contact anterior chin shields; labials 1-6 /1-7 undivided; and labials 8-9 divided. Four pairs of chin shields, first pair largest boomerang-shaped. Other pairs separated by small scales and do not border the mental groove ( Fig. 3c ). Six gular scales occur between last pair of chin shields and first ventral scale. Dorsal scales in 27 rows on the neck, 25 rows at midbody, and reduced to 21 rows near the vent. Scales in row one slightly taller than those in subsequent rows. Scales are smooth, and a few scales at midbody toward the vertebral midline are tuberculate. Ventrals rounded and broad, about 4-5 times wider than the length of a nearby dorsal scale; they number 158. Subcaudal scales are divided and number 44/ 45. Color in life: dorsum gray-black with iridescent scales, ventral surface and first four scale rows red-brown. Upper labials anterior to orbit gray-black, posterior upper labials red-brown. Black stripe from nape to angle of jaw. The color pattern on scale rows 1-4 at mid body is red with scattered brown pigment, on the remainder of scale rows each scale has light colored margin bordered on the inside by brown pigment, with a central irregular red spot; overall the dorsum is a uniform red-brown. Red-brown coloration extends onto crown of head and on chin (the mental and first 4-5 labials); coloration forms a line on margin of the lower labials, which outlines upper jaw. Ventral surface of body red; the ventral surface of tail braided in appearance with dark anterior spot on each scale and posterior portion of the scale has a red spot. Posterior upper labials also red.

Variation. – The two other specimens differ from the holotype in the following ways: (1) ZFMK 65825 has dorsal scales in 29 rows on the neck, 27 at midbody, and 22 rows near the vent; (2) ANSP 26411 has 155 ventrals and 44 subcaudal scales, while ZFMK 65825 has 155 ventrals and 45 subcaudal scales; (3) ZFMK 65825 has 16 supralabial scales on the right side and 17 supralabials on the left; (4) ANSP 26411 has the internasal divided into three small scales; (5) both of these have three supraoculars compared to two in the holotype; (6) ZFMK 65825 has a single subocular on the right side, and the pre- and postoculars on the left extend under the eye; (7) both of these have divided loreals, and upper labials 3-5 touching the loreal, while the holotype has a single loreal and supralabials 2-5 touching the loreal; (8) ANSP 26411 has a 2:2:3 temporal arrangement on the left side, and a 1:2:3 arrangement on the right, the latter arrangement is found in the other specimen as well; (9) neither of the other specimens has a horizontally divided rostral; (10) the other two females have total lengths of 643 mm and 762 mm, with tails that are 85 and 96 mm respectively.

Etymology. – We are pleased to name this new homalopsine snake in honor of the late Burmese herpetologist Ko Ko Gyi, Professor at Rangoon University, and the first zoologist to revise the entire subfamily Homalopsinae in the 20 th century. Without his efforts our current work would be much more difficult. We suggest that the common English name for this new snake should be Kapuas Mud Snake.

Distribution and natural history. – Enhydris gyii may be restricted to the Kapuas drainage basin of Kalimantan, Indonesia. However, the maps and data presented by Voris (2000) suggest that this species may, in the future, be found to occur in the drainage basins of central Sumatra. This suggestion is based on the observation that the Kapuas system and the central Sumatran drainages were connected at three different times during the last 250,000 years for a total connection time of about 95,000 years. The connections occurred when sea level was at or below the 50 m contour line. The specimens collected by Auliya 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 in 1996), and total annual precipitation is 4480 mm.

Nothing is known about the feeding habits or reproduction of this new species. While lowland endemicity is frequently considered to be minimal, the Kapaus River drainage has at least one area high in endemicity, the Danau Sentarum National Park (00°51'N 112°06'E), a Ramsar site since 1994, and gazetted a National Park in 1999. This is in an area about 700 km upstream in western Kalimantan, 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 Sibau River, on a level with Putussibau, very near to the type locality of E. gyii . The question of whether or not E. doriae and E. gyii are sympatric is unresolved. However, we have examined a single specimen of E. doriae from Kalimantan (UMMZ 65864) with no specific locality data.

Figures

Fig. 1. A comparison of the temporal regions of (A) Enhydris gyii (Holotype, ZFMK 65824) and (B) E. doriae, REP 0322. Enhydris gyii has fewer, large, plate like temporal scales.

Fig. 2. Enhydris gyii, new species, Holotype, ZFMK 65824 from Sungai Kapuas at Putussibau (0º52'N 112º55'E), where the Sibau River empties into the Kapuas River, Kapuas Hulu Regency, West Kalimantan, Indonesia. Photo: Mark Auliya.

Fig.3. Enhydris gyii, new species, Holotype, ZFMK 65824.A. dorsal view of head; B. lateral view of head; C. ventral view of head.