Amnesteophis Myers 2011, new genus
Creators: name: Myers, Charles W.
Publisher: name: Zenodo
Year: 2011
Subjects: Biodiversity
Taxonomy
Animalia
Chordata
Reptilia
Squamata
Dipsadidae
Amnesteophis

description: Amnesteophis, new genus   
 TYPE SPECIES: Enicognathus melanauchen Jan, 1863.   
 ETYMOLOGY: Amnesteophis (forgotten snake), from Greek amnēstos (ἄμvηστoς, “forgotten, no longer remembered”) + connective -e- + ophis (ὄφις, “snake”). Gender masculine. (For purposes of euphony, the derivation imposes elision of the final vowel in amnēstos, and the connective vowel - e - is employed rather than the - o - normally used in latinized compounding of Greek elements.)   
 Jan’s specific name melanauchen (a Schlegel manuscript name) appears compounded from the Greek combining element melan- (μέλαv, neuter of μέλας, melas, “black or very dark”) + auchēn (αὐχήv, “neck”)—a masculine noun in apposition, referring to a dark blotch on the neck.   
 CONTENT: Only Amnesteophis melanauchen (Jan), new combination.   
 Fig. 1. Enicognathus melanauchen Jan 1863. The adult male holotype (RMNH 393) in dorsal and ventral view. Shown life size (scale line = 10 mm).   
 DISTRIBUTION: Known only from “ Bahia ” (Jan, 1863a: 266; 1863b: 56)—the purported type locality in northeastern Brazil. The original catalog entry for the holotype (RMNH 393) is “ Bahia au Brésil.” 2   
 DEFINITION AND DIAGNOSIS: (Based on one adult male.) Genus of small colubrids less than 500 mm in total length, with tail length roughly a quarter of total length; habitus slender, body about as wide as high, slightly wider than head. Color Pattern: Dark nuchal blotch set off by pale crossbands, followed posteriorly by ill-defined narrow brown crossbands. Scutellation: Normal complement of colubrid head plates, possibly with diagnostic arrangement of temporals (in oblique rows, with both plates in first row in contact with labials); dorsal scales in 15-15-15 rows, feebly keeled, lacking apical pits or anal ridges; ventrals 145, anal plate divided, paired subcaudals 60. Osteology: Maxillary teeth about 25, increasing in size posteriorly, with slight anteriorposterior differentiation in shape; in a continuous series, no diastema; last two teeth slightly enlarged, set in a straight line with the several teeth immediately preceding. About 15 palatine teeth + 30 pterygoid teeth; about 20 teeth on dentary. No hypapophyses on posterior trunk vertebrae. Hemipenis: Feebly bilobed, acalyculate, small spines replaced distally by large flattened soft papillae; unforked sulcus spermaticus extending centripetally to apex of left lobe (sinistral sulcus); a nude area in crotch between the small papillate lobes.   
 Among Neotropical snakes, Amnesteophis melanauchen superficially seems most similar to Taeniophallus sensu lato. It has been compared by authors (Jan, Amaral) with the snake now known as Taeniophallus occipitalis, which shares the character of 15-15-15 dorsal scale rows and a somewhat similar color pattern. It shares with T. nicagus the character of a single (unforked) sulcus spermaticus. Amnesteophis differs from all Taeniophallus in lacking hemipenial calyces, in having the posterior maxillary teeth in a straight line, and in having feebly keeled (vs. smooth) dorsal scales. See Comparisons for further discussion.
description: Published as part of Myers, Charles W., 2011, A New Genus and New Tribe for Enicognathus melanauchen Jan, 1863, a Neglected South American Snake (Colubridae: Xenodontinae), with Taxonomic Notes on Some Dipsadinae, pp. 1-36 in American Museum Novitates 2011 (3715) on pages 3-5, DOI: 10.1206/3715.2, http://zenodo.org/record/5359400