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Eutrachelophis bassleri MYERS & MCDOWELL, 2014

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Higher TaxaColubridae (Dipsadinae), Colubroidea, Caenophidia, Alethinophidia, Serpentes, Squamata (snakes) 
Common Names 
SynonymEutrachelophis bassleri MYERS & MCDOWELL 2014 
DistributionPeru (Loreto), Ecuador

Type locality: Pisqui Hills, [upper] Río Pisqui, Province of Loreto  
TypesHolotype: AMNH 52926, an adult male, obtained by Harvey Bassler on January 15, 1927. The type locality is situated west of the Río Ucayali in the region of 8°00– 8°22’ S, 75°30–75°50’ W (see Remarks). This specimen (fig. 1A) is in good condition except that the maxillae and mandibles have been dissected out (possibly by Bassler), although still associated with the specimen. Total length 345 mm, tail length 101 mm; 2 preventrals (gulars wider than long), 133 ventrals + half ventral at anal plate, 67 pairs of subcaudals not counting terminal spine.
PARATYPES (11): ECUADOR: Pastaza Province: mouth Río Pucayacu, between Sarayacu and Montalvo, USNM 232826 (R. Olalla, Aug. 1948); Sarayacu, Río Bobonaza, USNM 232825 (R. Olalla, Nov. 1962). PERU: Huánuco Province: [Río] Pachitea, AMNH 52682 (H. Bassler, date?); Serranía de Sira, ridge above R ́ıo Llullapichis, 510 m (9°29’ S, 74°49’W), NMW 31795 (M. Henzl and B. Wallnöver, May 20, 1988). Loreto Province: Mishana, TCWC 40555, 41424, 41425 (P. Soini; collected over an eight year period fide Dixon and Soini, 1986: 114); Pampa Hermosa, R ́ıo Cushabatay, AMNH 55786 (H. Bassler, Sept. 1927);2 Pebas, Río Ampiyacu, 250 ft., AMNH 25193 (collector?); Río Tapiche, AMNH 52441 (H. Bassler, Jan. 1928); upper Río Utuquinia, AMNH 53473 (H. Bassler, Feb. 1928). 
DiagnosisDEFINITION AND DIAGNOSIS (genus): 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 laterad1); 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 in Myers & McDowell 2014), more ventrals (> 160), fewer maxillary teeth (about 13–17 + 2), and a calyculate hemipenis.

DIAGNOSIS (species): Eutrachelophis bassleri is a small snake (,400 mm total length) that resembles the somewhat larger E. steinbachi (to 558 mm) in having 15 dorsal scale rows and conspicuous paired ocelli on the nape. It differs from steinbachi in having a postocular wedge of pale color extending dorsad from the lip, and in having a pale broken, posterior collar (the rounded upper ends of which often resemble a second pair of ocelli when viewed from above), and in lacking oblique pale dorsolateral markings touching the eye. E. bassleri further differs in having dorsolat- eral lines of vague dark spots (or fused crossbars) rather than dark anterior stripes; a lateral line of pale dashes or dots lies on scale row 4 in bassleri, on row 6 in steinbachi. Eutrachelophis bassleri differs radically from steinbachi in having an undivided hemipenis with a nude, dome-shaped apex. 
CommentType species: Eutrachelophis bassleri MYERS & MCDOWELL 2014 is the type species of the genus Eutrachelophis MYERS & MCDOWELL 2014. 
EtymologyETYMOLOGY: 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.

The species is named in memory of Harvey Bassler (1883–1950), a former Research Associate in the American Museum’s Department of Herpetology. Bass- ler accumulated five of the 12 known specimens of this rare species during a decade devoted to petroleum exploration and zoo- 
  • Echevarría, Lourdes Y. and Pablo J. Venegas. 2015. Eutrachelophis bassleri coloration and photographs in life. Herpetological Review 46 (3): 449 - get paper here
  • Myers, Charles W. and Samuel B. McDowell 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 385 (1) : 1-112. - get paper here
  • Torres-Carvajal O, Pazmiño-Otamendi G, Salazar-Valenzuela D. 2019. Reptiles of Ecuador: a resource-rich portal, with a dynamic checklist and photographic guides. Amphibian & Reptile Conservation 13 (1): [General Section]: 209–229 (e178) - get paper here
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