Salween River Basin Mud Snake

description

Description of holotype (Figs. 3 – 4). Head depressed, distinct from neck; snout short and rounded, rostrum tapers downwards; rostral scale pentagonal, nearly as broad as tall, visible from above; eye moderate in size, pupils rounded; nasals semi-divided with nasal groove contacting first supralabial, nare in center (on left side of snout is a small, aberrant, triangular scale positioned between rostral, nasal and first supralabial); internasal small, quadrangular, not in contact with loreal; loreal 1 / 1, quadrangular, contacting first three supralabials on right side and supralabials 1, 2 and 4 on left side; preocular 1 / 1; supraocular 1 / 1; postoculars 2 / 2; prefrontals 2, in broad contact with each other, frontal, internasal, loreals, preoculars, supraoculars, and posterior tip of nasals; frontal pentagonal, 1.4 times longer than supraocular; parietals elongate; temporal scale formula 1 + 2 + 3; supralabials 9 / 8, largest supralabial 7 / 6, smallest 3 / 8, supralabial entering orbit 5 / 4 (on left side of head there is fragmentation of supralabial scales with third supralabial being small and sandwiched beneath second and fourth supralabials (Fig. 4 b); infralabials 10 / 10

A new species of Mud Snake (Serpentes, Homalopsidae, Gyiophis Murphy & Voris, 2014) from Myanmar with a first molecular phylogenetic assessment of the genus

diagnosis

Diagnosis. Gyiophis salweenensis sp. nov. is separated from all congeners by having a unique combination of the following characters: a narrow rostral scale; the first three dorsal scale rows square; 129 (female) ventral scales; 30 / 29 (female) paired subcaudals; a divided cloacal plate; eight or nine supralabials; 10 infralabials; a maximum total length of 416 mm; relative tail length ratio of 0.13; a ventral patterning lacking a central spot on each ventral scale; the presence of a faint stripe on the lower, dorsal scale rows; and four rows of dark spots on the dorsum (Table 1).

A new species of Mud Snake (Serpentes, Homalopsidae, Gyiophis Murphy & Voris, 2014) from Myanmar with a first molecular phylogenetic assessment of the genus

distribution

Distribution (Fig. 2). Gyiophis salweenensis sp. nov. is only known from the type locality near Sanpel Cave, Mon State, Myanmar. It is expected to be wider ranging throughout the Salween River Basin and found wherever appropriate habitat occurs. Natural history (Fig. 5). The holotype was found at approximately 1930 hours crossing a narrow dirt road between flooded fields that we presume to be its natural habitat. The weather was overcast and it rained later that night. Many other species of homalopsids are semiaquatic and commonly found in streams, rivers, ponds, and flooded rice fields (Murphy 2007 a; Stuebing et al. 2014). Gyiophis salweenensis sp. nov. is expected to share a similar life history and the valvular nostrils located dorsally on the snout indicate this species probably spends a large part of its life in the water. Homalopsid snakes such as Enhydris enhydris, Homalopsis buccata (Linnaeus, 1758) and Hypsiscopus plumbea have been observed crawling on land and crossing roads during wet weather (Voris & Karns 1996; Lim & D’Rozario 2009; EQSH personal obs.) and the holotype of G. salweenensis sp. nov. could have been dispersing to a new area as well. The holotype also had

A new species of Mud Snake (Serpentes, Homalopsidae, Gyiophis Murphy & Voris, 2014) from Myanmar with a first molecular phylogenetic assessment of the genus

etymology

Etymology. The specific epithet salweenensis is in reference to area where the holotype was found which is close to the vicinity of the Salween River near the city of Mawlamyine. The suffix ensis is a Latin derivation meaning “ from ” or “ inhabiting. ” It renders the specific epithet an adjective that must be in grammatical accord with the gender of Gyiophis. Comparison. Gyiophis salweenensis sp. nov. is distinguishable from G. maculosa by the shape of the dorsal scales of first three rows (square vs. ovate), the ventral scale pattern (absence of a central spot on each ventral scale vs. its presence), and a stripe running through the scales of the lower dorsal scale row (faint one vs. absent). It is further distinguished from G. vorisi by its lower number of ventrals (129 vs. 142 – 152), lower number of subcaudals (30 / 29 vs. 41 – 58), shape of the rostral scale (narrow vs. broad), and the number of rows of spots on the dorsum (four vs. three) (Table 1). It differs from the other species of homalopsids found in Myanmar by unique suite of characters presented in the key below.

A new species of Mud Snake (Serpentes, Homalopsidae, Gyiophis Murphy & Voris, 2014) from Myanmar with a first molecular phylogenetic assessment of the genus