Parahelicops Bourret, 1934

David, Patrick, Pauwels, Olivier S. G., Nguyen, Truong Quang & Vogel, Gernot, 2015, On the taxonomic status of the Thai endemic freshwater snake Parahelicops boonsongi, with the erection of a new genus (Squamata: Natricidae), Zootaxa 3948 (2), pp. 203-217 : 208

Parahelicops Bourret, 1934

Parahelicops Bourret, 1934b: 170 [separate: p. 6].— Type species. Parahelicops annamensis Bourret, 1934 by monotypy.

Diagnosis. A genus of medium-sized snakes of the family Natricidae characterized by (1) body elongate, (2) head moderately distinct from the neck, (3) eye moderate in size with a round pupil, (4) maxillary teeth progressively increasing in size in a continuous series, last 2 moderately enlarged, not separated from anterior teeth by a diastema, (5) nostrils piercing distinctly dorsolaterally, (6) upper head scales complete as for typical colubroids but prefrontal single in most specimens, (7) internasals distinctly narrowed anteriorly, (8) all SL distinctly longer than high, (9) dorsal scales in 15 or 17 rows at midbody, moderately keeled at midbody, strongly keeled posteriorly, especially before vent, (10) caudal scales around the base of the tail very strongly keeled, (11) more than 110 SC, paired, (12) hemipenes short, thin, single, and spinose.

Although Parahelicops annamensis usually has a single prefrontal, as in most species of Opisthotropis , it differs from this latter genus, as defined above, by (1) maxillary teeth enlarged vs. subequal teeth in Opisthotropis , (2) tail long vs. rather short or average in Opisthotropis (see the descriptions), (3) head moderately distinct from the neck vs. barely distinct in Opisthotropis , (4) eye large vs. small in Opisthotropis , (5) nostrils directed dorsolaterally vs. directed upwards in Opisthotropis , (6) SL much longer than high vs. distinctly higher than long in Opisthotropis , and (7) dorsal pattern with two rows of large rusty blotches, vs. more or less uniform, or with crossbars in species of Opisthotropis .

Contents As currently defined, the genus Parahelicops includes only a single species, Parahelicops annamensis Bourret, 1934 .