Eutrachelophis, Myers & McDowell, 2014

Myers, Charles W. & McDowell, Samuel B., 2014, New Taxa And Cryptic Species Of Neotropical Snakes (Xenodontinae), With Commentary On Hemipenes As Generic And Specific Characters, Bulletin of the American Museum of Natural History 2014 (385), pp. 1-112 : 6-8

Eutrachelophis , new genus

TYPE SPECIES: Eutrachelophis bassleri , new species.

ETYMOLOGY: The intended meaning of the generic name is ‘‘beautiful-necked snake.’’ It is compounded from the prefix eu - (beautiful) + trachelos (neck) + ophis (a serpent), all from the Greek. Gender masculine.

CONTENT: Two named species, as described or redescribed below: Eutrachelophis bassleri , new species, E. steinbachi ( Boulenger, 1905) , new combination. A new species related to E. bassleri awaits description.

DEFINITION AND DIAGNOSIS: Small terrestrial colubrids lacking hypapophyses (hemal

keel present) on posterior trunk vertebrae. High number (about 25–30) of prediastemal maxillary teeth followed by diastema and two enlarged, ungrooved teeth (the last offset laterad 1); differentiated rear maxillary teeth not accompanied by correspondingly conspicuous differentiation of Duvernoy’s gland. Spiny hemipenis either divided, with spines to apices of lobes, or single with distal nude area; hemipenis lacking calyces, flounces, or apical discs; sulcus spermaticus forked proximally, with branches centrifugal (at least when organ is everted). Eye large, with round pupil. Habitus slender, with smooth dorsal scales in 15-15-15 rows; single scale pits present or absent; no anal ridges. Normal complement of colubrid head plates;, 150 ventrals; anal plate divided,, 90 subcaudals, paired. Color pattern with black-rimmed pale ocelli or elongated spots on head or on head and neck; dorsum with dark stripes or spots anteriorly, becoming nearly uniform posteriorly.

The above combination of traits is unique. Externally, the species of Eutrachelophis are readily differentiated from most other New World snakes by the combination of 15 dorsal scale rows and the presence of conspicuous ocellar markings on head or on head and neck. There may be a vague resemblance in pattern with some specimens of the variable Taeniophallus occipitalis , which also has 15 scale rows, but occipitalis differs in having a white canthal line (fig. 15B), more ventrals (. 160), fewer maxillary teeth (about 13–17 + 2), and a calyculate hemipenis.

DISTRIBUTION: Lowland rain forest, in western Amazonia—in Ecuador, Peru, Bolivia —and middle Amazonia in Brazil (map 1).

1 That is, offset laterad from a straight line through the posterior several teeth or offset laterad from a line from the last ‘‘prediastemal’’ tooth to the first enlarged tooth ( Myers, 1974: 28; 2011: 9–10, 27–28). Posteriorly offset teeth, whether grooved or not, characterize most ‘‘xenodontines,’’ although there is great variability in maxillary shape and the first enlarged tooth (‘‘fang’’) sometimes may better be described as offset mediad to the general line of the tooth row. Presence or absence of a diastema often is diagnostic, but in occasional ‘‘xenodontines’’ (e.g., Rhadinaea decorata ) it also seems to be correlated with the total number of maxillary teeth. The offset of the ultimate enlarged tooth (‘‘fang’’) is relatively slight in Eutrachelophis .