Xenochrophis asperrimus
Creators: name: Published, First
Publisher: name: Zenodo
Year: 2012
Subjects: Biodiversity
Taxonomy
Animalia
Chordata
Reptilia
Squamata
Natricidae
Xenochrophis
Xenochrophis asperrimus

description: Xenochrophis asperrimus (Boulenger, 1891)   
Figs. 27–28  
 Tropidonotus asperrimus Boulenger, 1891: 281.—Type locality. “ Ceylon ”, now Sri Lanka.— Syntypes. BMNH 1946.1.13.33– 34, BMNH 1946.1.12.43, BMNH 1946.1.15.22–23, BMNH 1946.1.15.17, BMNH 1946.1.15.30, BMNH 1946.1.7.60–61, BMNH 1946.1.12.74–75, BMNH 1946.1.12.85.   
 Taxonomic comments. Wall (1921) synonymized this taxon with X. piscator. However, our data show that it is distinct from X. piscator and deserves a full species status.   
 Identification. Body cylindrical, stout; tail length moderate. Maximum total length 890 mm for female BMNH 1910.3.16.24. Examined males much shorter (maximum length females / males 1.41), longest male 630 mm (FMNH 121493). Relative tail length sexually dimorphic: tail 28.3–31.4 % of total length in males, 25.7–28.9 % in females. The head is distinct from neck, the eye is small or average, i.e. its diameter is at most equal to the distance between the edge of the upper lip and the lower margin of eye. Dorsal scales arranged in 19–19–17 rows, strongly keeled, with keels forming sharp lines on the posterior part of the body and on the tail, only the outer row is smooth. The vertebral scales are not enlarged. The ventral scales are 127–133 in males and 132–142 in females, unkeeled; the subcaudals are 77–92 in 9 males and 75–83 in 9 females, unkeeled and paired. The anal plate is divided. Head scalation includes 1 loreal, 1 preocular, 3 (in one case 2) postoculars, 2 anterior temporals, and 2 or 3 posterior temporals, 9 supralabials (in two cases 10, in one case 11) whose 4 th to 5 th enter orbit (in the cases with 10 or 11 supralabials it’s the 5 th and 6 th), 10 (in three cases 9, in one case 11) infralabials, whose the 5 (in two cases 4 in one case 6) first touch the anterior chin shields.   
Anterior half of body pale olive, brownish-olive or reddish-grey, with two series of 22–32 more or less distinct, large dark brown, black-edged blotches, more or less rounded or rhomboidal, alternating, partly confluent on vertebral line and possibly forming a sinuous stripe; these blotches might give the appearance of lateral triangles in many specimens; posteriorly dark olive, usually with blackish-brown blotches quincuncially arranged; sometimes a series of yellow dorsolateral spots.  
Head dorsally dark olive or olive brown. Two oblique, black streaks on each side of head, one below, the other one behind eye respectively; nuchal marking sometimes absent, but usually a single blotch, in few cases two blotches. Venter colour from yellowish-green to tan or yellowish-ochre; tip and outer quarter of each ventral clouded with dark or lead-grey, more or less distinct; a short, black, usually little distinct streak on posterior outer margin of each ventral, not forming a complete crossbar on the middle of ventral. In some specimens, the streak appears only about every four or five ventrals; in some others, streak is replaced by clouded area. Rarely, venter nearly patternless. Subcaudals with dark margins or with dark spots (Boulenger 1891; Smith 1943; Taylor 1950; Somaweera 2006; pers. obs.).  
 Distribution. Sri Lanka. This species is endemic to Sri Lanka, where it is common and found in all provinces and climatic zones (De Silva 1990). It is sympatric with Xenochrophis cf. piscator.   
 Discussion. Boulenger (1891) and Smith (1943) gave a slightly higher ventral count of 131–146 (our data, sexes combined 127–142), but they did not count according to Dowling’s method. The variation of the subcaudal counts of Boulenger (64–90) is greater than ours (sexes combined 75–92), that of Smith a bit greater than ours (73– 93). It is possible that Boulenger included a specimen with an incomplete tail. Taylor (1950) mentioned the pholidosis of one specimen with 133 ventrals and 72 subcaudals.   
 Material examined (29 specimens). Sri Lanka. Central Province. BMNH 1905.3.25.85, BMNH 1946.1.15.30, “Punduloya”, now Pundaluoya, 4,000 ft. Sabaragamuwa Province. BMNH 1982.600 – 01, Kuru Ganga River System, Ratnapura District. Southern Province. BMNH 1910.3.16.24, Gadakarircha, Galle District; ZMH R07929, “Vakvella, SW Ceylon”, now Wakwella, Galle District. Southern Province. FMNH 121493, no locality. No locality. BMNH 1931.5.13.35, BMNH 1931.5.13.37–38, BMNH 1931.5.13.41–42, BMNH 1946.1.7.60–61, BMNH 1946.1.12.73–74, BMNH 1946.1.12.85, “ BMNH 1946.1.13.33–34, BMNH 1946.1.13.39–40, “Ceylon”; MNHN 1999.9463, “Sri Lanka”; MNHN 1999.7950, Philippines (in error); MNHN 7411.0012, Philippines (in error); ZMB 14299, Ceylon; ZMH R07923, ZMH R07934, ZMH R07936, “Ceylon”.
description: Published as part of Published, First, 2012, 3473, pp. 1-60 in Zootaxa 3473 on pages 32-33