Oxybelis aeneus auratus

Jadin, Robert C., Blair, Christopher, Orlofske, Sarah A., Jowers, Michael J., Rivas, Gilson A., Vitt, Laurie J., Ray, Julie M., Smith, Eric N. & Murphy, John C., 2020, Not withering on the evolutionary vine: systematic revision of the Brown Vine Snake (Reptilia: Squamata: Oxybelis) from its northern distribution, Organisms Diversity & Evolution (New York, N. Y.) 20 (4), pp. 723-746 : 736-737

Oxybelis aeneus auratus – Bogert and Oliver 1945: 381 Oxybelis aeneus – Keiser 1974: 7

Holotype UIMNH 25069 ( Fig. 11 ), a female from 36 km northwest of Ciudad Maíz (circa 22° 30′ N, 99° 56′ W), San Luis Potosí, Mexico, designated by Taylor, 1941: 128

Diagnosis Using data from our examination of specimens from Eastern Mexico, we constructed the following description for Oxybelis potosiensis . A vine snake with (1) two or three upper labials (4–5 or 4–5–6) bordering the orbit; (2) transverse black bars on the anterior body; (3) venter finely mottled, a stripe or stripes are not apparent; (4) eye diameter longer than preocular; (5) second pair of chin shields are in contact for most of their length; (6) nine upper labials, two or three upper labials behind the orbit; (7) snout from above is very broad, slightly tapered, and rostral is very rounded (snout type C); (8) supraocular and prefrontals about the same length; (9) last upper labial equal or greater in length than the primary temporal; (10) underside of head uniform white or cream; and (11) second upper labial does not contact the preocular.

Description of holotype ( Fig. 11 ) Rostral is visible from above; preoculars extend slightly on to the crown between the prefrontals and supraoculars, and the postoculars can be seen from above. Preocular scale is shorter than eye diameter. Scales bordering the orbit: preocular, the supraocular, two small postoculars, and upper labials 5–6 on the left and 4–5 on the right. The primary temporal is in contact with both postoculars, the parietal, two secondary temporals, and upper labials 6–7–8–9. Eight upper labials on the right and nine on the left; the shortest upper labial can be the first or the eighth; the longest upper labial is the last (eighth or ninth). Upper labials 1–2 contact the nasal, 2–3 contact the prefrontal-loreal, and 3–4 contact the preocular. The tallest upper labial can be the fifth or sixth. Lower labials 9–10; the first four contact the anterior chin shields, a total of six contact both pair of chin shields. The anterior pair of chin shields are shorter (about 60%) than the length of the second pair of chin shields; the second pair are in contact anteriorly and partially separated by a pair of scales posteriorly. Dorsal scales are in 17–17–13 rows. Ventrals 196, subcaudals 160.

Variation In males, total lengths vary from 1175 to 1535 mm (n = 4, x = 1371.75, SD = 164.08) and tails vary from 500 to 628 mm (n = 4, x = 564.75, SD = 58.09). Tail/SVL ratios in males vary from 0.67 to 0.69 (x = 0.68, SD = 0.01). In females, total lengths vary from 804 to 1272 mm (n = 3, x = 1083.33, SD = 201.53), SVL vary from 734 to 804 mm (n = 3, x = 761.67, SD = 30.40), and tail lengths vary from 440 to 525 mm (n = 2, x = 482.5, SD = 42.50); one female had a tail/ SVL ratio that was 0.70.

Ventrals in males vary from 174 to 190 (n = 6, x = 185.67, SD = 5.73); ventrals in females vary from 186 to 195 (n = 3, x = 191.67, SD = 4.03). No subcaudal counts were taken because of broken or questionable tail tips.

Size: To at least 1290 mm total length

Coloration and pattern In alcohol (UIMNH 25069), head and body gray–brown, upper labials cream and separated from the gray–brown by a black stripe; ventral surface of head cream transitioning to yellow posteriorly. Transverse black bars on the anterior body. No ventral stripes ( Fig. 11 ).

Geographic distribution This species occurs in San Luis Postosí and northern Veracruz, southward to Yucatan, Mexico, and Belize.

Comparison A vine snake with nine upper labials, two bordering the orbit, eye diameter greater than the length of the preocular, and second pair of chin shields in contact for most of their length. Specimens of Oxybelis aeneus and those from northern South America have the second pair of chin shields separated by smaller scales. Specimens of O. aeneus , O. koehleri , O. microphthalmus , and those from Panama have three upper labials bordering the orbit.

Figures

Fig. 11 a–d Holotype of Oxybelis potosiensis Taylor 1941 (UIMNH 25069) from San Luis Potosí, Mexico; a whole specimen; b the crown, note the lack of a constriction anterior to the eyes, rostral not visible from above, and the relatively broad snout; c the profile; d arrangement of the chin shields