Cerberus microlepis Boulenger

Murphy, John C., Voris, Harold K. & Karns, Daryl R., 2012, The dog-faced water snakes, a revision of the genus Cerberus Cuvier, (Squamata, Serpentes, Homalopsidae), with the description of a new species, Zootaxa 3484, pp. 1-34 : 13

Cerberus microlepis Boulenger

Figure 6

Cerberus cinereus Gray 1849:64 (in part).

Cerberus microlepis Boulenger 1896 , 3:18. Type locality: " Philippines." Collector: H. Cuming. Syntypes: BMNH 1946.1.7.24– 25; Gyi 1970:153; Alfaro et al. 2004:1277; Murphy 2007:69; Alfaro et al. 2008:576. Hurria microlepis — Taylor 1922:114.

Distribution. Cerberus microlepis is known only from Lake Buhi (~ 13°26’N 123°31’E), a small freshwater lake on the island of Luzon, in the Philippines. The lake is about 18 km 2, and is positioned on the eastern side of Mt Iriga about 200 feet above sea level; a distance of 15 km from the coast. The lake was formed in 1641 by an earthquake that collapsed the side of Mt Iriga and formed a dam ( Karns et al. 2000, Alfaro et al. 2004). Given the geologically recent formation of this lake it is possible that one or more earlier mud slide(s), perhaps associated with Mt Iriga eruptions, created a wetland at the same location thus providing suitable habitat for Cerberus in the more distant past.

Diagnosis. Cerberus microlepis can be distinguished from all other members of the genus by its 27 to 31 scale rows at midbody, all other species have 21 to 25 scale rows at mid-body; the imbricate plate-like scales on the crown have a slightly thickened appearance; last upper labial is horizontally divided; and the venter is mottled. Cerberus australis has 23 scale rows at mid-body; lacks keels anterior to the angle of the jaw and the first labial does not contact the loreal (it does in microlepsis). Cerberus dunsoni has 23 scale rows at mid body, rounded juxtaposed scales on the crown, and a uniform black venter. Cerberus rynchops has 25 scale rows at mid body (rarely 23); keeled scales on the crown of the head anterior to the angle of the jaw, and the last two upper labials are horizontally divided. Cerberus schneiderii usually has 23 scale rows at mid-body (rarely 21 or 25), the last upper labial is horizontally divided

Variation. The largest male was 768 mm TL with a 158 mm tail. The largest female 1046 mm TL with a 161 mm tail. The largest remaining fragment of the frontal scale is shorter in length than the length of the supraocular in all 16 specimens examined. The loreal contacts the subocular on all 22 sides examined and the preocular contacts the upper labials in all specimens. Largest upper labial 7 (53%), 8 (34%), or 6 (9%); first horizontally divided upper labial posterior to the eye 7 (3%), 8(47%), or 9(50%); labial(s) under the orbit 4+5 (3%), 5 (47%), 5+6 (38%), or 6 (12%); horizontally divided upper labials posterior to the orbit: 1 (91%), 2 (4.5%), or none (4.5%). Dorsal scale rows on anterior body 28–33, at midbody 28–31, and posterior body 20–25. Ventral scales wide and rounded; 160– 172 in males; 159–166 in females. The subcaudal scales divided; 60–70 in males; 54–61 in females. Male tails 23– 27% of SVL. Female tails 18–22% of SVL.

Figures

FIGURE 6. Lake Buhi Bockadam, Cerberus microlepis. USNM 197854. JCM.