Guerrero Slender Leaf Litter Snake

description

Description of the holotype. Adult female with few small supracloacal tubercles; head length 9.5; head width 4.0; neck 3.0; snout-vent length 256; tail missing perhaps no more than 2 – 3 distal subcaudals, length 85 + N; eye diameter 1.1; naris to anterior edge of eye 3.0; head scales arranged in typical colubrid fashion with paired internasals, paired prefrontals, broad median frontal, narrow paired supraoculars, and elongate paired parietals; internasal suture 0.6, about 33 % length of prefrontal suture; frontal length 3.0, about 120 % as long as its distance from tip of snout, 67 % as long as parietals; interocular distance 3.5, 63 % occupied by frontal; mental broad, 1.5 x 1.0; two pairs of genials, subequal in size, posterior pair wing-shaped, deeply incised along median suture. Dorsal scales smooth, in 17 / 17 / 17 rows; four rows at midlength of tail; apical pits appear to be absent; supralabials 7 / 7, third and fourth entering orbit; infralabials 7 / 8, first pair in contact behind mental along midventer, first to third / first to fourth in contact with anterior genials, respectively; third and fourth / fourth and fifth infralabials in contact with posterior genials, respe

A new species of Rhadinella (Serpentes: Colubridae) from the Sierra Madre del Sur of Guerrero, Mexico

diagnosis

Diagnosis. A member of Rhadinella, genus characterized by gracile body, head only slightly distinct from neck; inverted dark U-shaped marking on rostral; anterior supralabials usually with dark edges and pale centers; conspicuous or at least evidence of pale collar on neck; with reduced to small supracloacal tubercles in adult females; no subpreocular scale; posterior (2 – 7) teeth larger and thicker than preceding teeth, all enlarged teeth on same plane, no broad diastema; with basal nude pocket on hemipenis. Rhadinella dysmica is further characterized by the combination of a distinctive white collar, undivided at middorsum, extending 2.0 – 2.5 scale lengths at middorsum and 3 – 4 scale lengths on side of head; temporals 1 + 2; smooth dorsal scale rows 17, unreduced throughout body; ventrals 172; cloacal scute divided; divided subcaudals incomplete 63 + N; dorsal coloration dark brown to blackish, almost totally obfuscating longitudinal striping, ground color barely extending to lateral edges of ventrals. Rhadinella dysmica may be distinguished from many congeners (i. e., R. godmani, R. hannsteini, R. hempsteadae, R. kanalchuchan, R. kinkelini, R. lachrymans, R. montecristoi, R. p

A new species of Rhadinella (Serpentes: Colubridae) from the Sierra Madre del Sur of Guerrero, Mexico

distribution

Distribution and habitat. The type-locality lies at 432 m asl at the edge of a small valley occupied the small village of Cuajilotla (Fig. 4) in the foothills of the eastern portion of Sierra Madre del Sur in Guerrero in tropical deciduous forest. The predominant types of vegetation at higher elevations in the region are oak forest and pine-oak forest, grading into tropical deciduous forest, which is restricted to the lowlands of foothills, valleys, and slopes (Leopold 1950). The type-locality (Fig. 5) is drained by the Río Chapolapa, an upper tributary of the Río Omitlán- Azul, which flows into the Río Papagayo. Other species of amphibian and reptiles recorded between 340 – 432 m in the vicinity of the type-locality were Rhinella marina, Craugastor rugulosus, Agalychnis dacnicolor, Smilisca baudinii, Anolis dunni, Aspidoscelis guttata, Holcosus undulatus, Phyllodactylus lanei, Phyllodactylus tuberculosus, Ctenosaura pectinata, Sceloporus siniferus, Urosaurus bicarinatus, Boa imperator (sensu Hynková et al., 2009), and Leptodeira annulata. The taxonomic histories of snakes placed in the genus Rhadinella were most recently discussed by Myers (2011) and Campbell (2015). Most of the s

A new species of Rhadinella (Serpentes: Colubridae) from the Sierra Madre del Sur of Guerrero, Mexico

etymology

Etymology. The specific epithet is derived from the Greek ἐφέσπερος (dysmikos), meaning western, in reference to the westernmost distribution of this species of the genus. We propose standard English and Spanish names of Guerrero Slender Leaf Litter Snake and Hojarasquera Delgada de Guerrero, respectively.

A new species of Rhadinella (Serpentes: Colubridae) from the Sierra Madre del Sur of Guerrero, Mexico