Donaji's Slender Leaflitter Snake

description

Description of holotype. Adult male as indicated by well developed hemipenes and cloacal ridges; head length 7.9; snout-vent length 220; tail incomplete, length 48 +; eye diameter 1.0; naris to anterior edge of eye 2.0; internasal suture 0.3, about 17 % length of prefrontal suture; frontal 2.5, about 93 % as long as its distance from tip of snout, 63 % as long as parietals. Dorsal scales smooth, in 17 / 17 / 17 rows; apical pits appear to be absent; head scales arranged in typical colubrid fashion with paired internasals, paired prefrontals, broad median frontal, narrow paired supraoculars, and paired parietals; supralabials 7 / 7, fourth below orbit; infralabials 7 / 7, first to third in contact with anterior genials, third and fourth in contact with posterior genials; preoculars 1 / 1, subpreocular absent; postoculars 1 / 1; temporals 1 + 2; preventrals 1; ventrals 166; cloacal plate divided; tail incomplete, subcaudals 40, divided. In preservative (alcohol after formalin) head mostly pale yellow, extending onto the lips; lateral surface of head mostly pale except for dark brown pigment present on rostral above lingual groove, along lower loreal suture, around periphery of eye, o

A new species of Rhadinella (Serpentes: Colubridae) from the Pacific versant of Oaxaca, Mexico

diagnosis

Diagnosis. Small, gracile snake of the genus Rhadinella in which the head is only slightly distinct from neck. The head pattern alone is diagnostic from all other species of Rhadinella, consisting of a mostly pale dorsum with irregular head blotching followed by an immaculate pale collar (Fig. 1). Rhadinella donaji can easily be distinguished from most species of Rhadinella, such as R. hannsteini and R. kinkelini, which posses a distinct body pattern of longitudinal stripes. Rhadinella donaji can be most easily confused with R. schistosa, R. pilonaorum, and R. posadasi, all of which have a mostly dark dorsum, pale dashes on most dorsal scales, and often an indistinct dark vertebral line. Characteristics defining R. donaji include seven supralabials; third and fourth infralabials contacting posterior genials; 166 ventrals in single male; a mostly pale head with a relatively small amount of brown mottling; a pale collar that extends three scales posterior of the ultimate supralabial; an extremely faint dark vertebral stripe that involves only the vertebral scale row; no lateral stripe, but pale dashes that are less developed or absent on the third scale row; no dark pigment on latera

A new species of Rhadinella (Serpentes: Colubridae) from the Pacific versant of Oaxaca, Mexico

distribution

Distribution and habitat. The type-locality is a heavily karstic region with many sharp rock ridges and pinnacles (Fig. 4) forming a honeycombed landscape that makes field work difficult. Pine-oak forest covers the landscape and in some areas a moderate accumulation of leaf litter may be found in rock crevices. The slope of the type-locality is drained by the upper tributaries of the Río Atoyac, which is a tributary of the Río Verde. The snakes now placed in the genus Rhadinella have had a somewhat tortuous taxonomic history. Bailey (1940) provided a summary of Mexican species of Rhadinaea (sensu lato) in which he considered only one species of what later was to become part of the Rhadinaea godmani group, namely R. lachrymans. However, he pointed out that R. lachrymans was distinct from all other species he reported from Mexico, but that it possessed similarities with R. godmani from western Guatemala. Stuart & Bailey (1941) described several new species of Rhadinaea from the highlands of Guatemala. They relegated two of these species, along with R. godmani and R. serperaster, to what they called the Rhadinaea lachrymans group, which corresponds well with what was subsequently term

A new species of Rhadinella (Serpentes: Colubridae) from the Pacific versant of Oaxaca, Mexico

etymology

Etymology. This species is offered to the Princess Donají [pronounced softly in Zapotec as Donashi], who according to Zapotec legend was the beautiful granddaughter of King Cosijoeza, the last great king of the Zapotec civilization. She was taken hostage and subsequently decapitated by factions warring with the Zapotecs. Her head was lost, only to be discovered miraculously much later still in a fresh state by a shepherd digging up a flower. Her visage is represented on the coat of arms of the city of Oaxaca de Juárez. Proposed Standard English and Spanish names: Donaji’s Slender Leaflitter Snake and Hojarasquera Delgada de Donaji, respectively.

A new species of Rhadinella (Serpentes: Colubridae) from the Pacific versant of Oaxaca, Mexico