Oxybelis aeneus ( Wagler, 1824)

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 : 730-733

Oxybelis aeneus ( Wagler, 1824)

Brown Vine Snake

Dryinus aeneus – Wagler 1824

Oxybelis aeneus – Duméril et al. 1854: 819

Dryophis acuminata – Günther 1858: 156

Oxybelis aeneus aeneus – Bogert and Oliver 1945: 391 Oxybelis aeneus – Keiser 1974: 7

Lectotype ZSM 2645/0 from the forest along the Solimõens River, near Ega, now Tefé, Amazonas, Brazil (~ 03° 21′ S, 64° 42′ W). Keiser (1974) considered ZSM 2645/0 the holotype but Hoogmoed and Gruber (1983) gave it lectotype status suggesting that Wagler, 1824 had seen more than one specimen.

Diagnosis Using data from Keiser (1974) and our examination of specimens from Central Brazil ( Fig. 7 ), we constructed the following description for Oxybelis aeneus . A vine snake with (1) three upper labials (4–5–6) bordering the orbit; (2) black bars or spots present on the anterior body; (3) no stripes on the ventral surface; venter is mottled; (4) eye diameter greater than preocular; (5) second pair of chin shields separated by smaller scales for most of its length; (6) nine upper labials, three located behind the orbit; (7) snout from above narrow, tapered, and flat at rostral (snout type B); (8) supraocular slightly longer than prefrontals; (9) last upper labial longer than primary temporal; (10) lower surface of head uniform in color; and (11) second upper labial does not contact the preocular.

Tail is 0.7 of the SVL; the eye diameter is 1.4 times the length of the preocular scale and 0.93 of the internasal length. Primary temporal contacts both postoculars, the parietal, and two secondary temporals. Upper labials 6–7–8–9 contact the primary temporal. Ventral counts in males 179–197 (n = 15, x = 188.8, SD = 9.00). In females, ventral counts ranged from 184 to 203 (n = 20, x = 192.1, SD = 9.54). Subcaudal counts 154–188 in males (n = 12, x = 169.5, SD = 17.16) and 146–184 (n = 15, x = 168.2, SD = 19.08) in females. It has 17–20 maxillary teeth.

Variation The rostral is visible from above and followed by nine plate-like scales on the crown: a pair of internasals, a pair of prefrontals, the frontal and two larger supraoculars, and a pair of parietals. The preoculars extend slightly on to the crown between the prefrontals and supraoculars. In profile, the nasal scale is elongate, extending from the edge of the rostral, beyond the posterior edge of the internasal to the anterior border of the fused prefrontal–loreal. The preocular scale is short and less than the length of the eye’ s diameter. The eye diameter/ internasal ratio for one specimen is 0.93. Scales bordering the orbit are the preocular, the supraocular, two small postoculars, and upper labials 4–5–6. The primary temporal contacts both analyses of the partitioned dataset obtained from IQ-TREE. Inserts are O. fulgidus (MBLUZ 1480; above) from the Sierra de Imataca, Bolivar, Venezuela, and O. aeneus NSA (below) photographed at Quebrada Chacaito, El Avila National Park, north of Caracas, Venezuela. Photographs were taken by D.A. Briceño C. and L.A. Rodríguez J., respectively. Colors correspond to those in Figs. 3 and 4

postoculars, the parietal, and two secondary temporals; upper labials 6–7–8–9 contact the primary temporal. Upper labials are usually nine but range from 8 to 10. The eighth upper labial is the shortest. The ninth upper labial is the longest. Upper labials 1–2 contact the nasal, 2–3 contact the prefrontal–loreal, and 3–4

populations from South America (SA), upper Central America (UCA = Guatemala and Yucatan), lower Central America (LCA = Honduras and Mexico), and Central America (CA = UCA, LCA, and O. wilsoni ) while those after O. aeneus refer to populations from Panama (P), northern South America (NSA), Eastern Mexico (EM), western region (WR), and Central America (CA)

contact the preocular. The tallest upper labial can be the sixth or seventh. Lower labials range from 8 to 10 (usually nine). The first four (rarely five) contact the anterior chin shields, a total of six contact both pair of chin shields. The anterior pair of chin shields are shorter (about 50%) than the length of the second pair of chin shields; the second pair are completely separated by smaller scales. Ventral counts in males vary from 179 to 197 (n = 15, x = 188.8, SD = 9.00). Ventral counts in females vary from 184 to 203 (n = 20, x = 192.1, SD = 9.54). Subcaudal counts 154–188 in males (n = 12, x = 169.5, SD = 17.16) and 146–184 in females (n = 15, x = 168.2, SD = 19.08). Maxillary teeth vary from 17 to 20.

Coloration and pattern The crown of the head and upper face are golden brown to tan. The upper labials and ventral surface of the head are a uniform cream. The transition in color is separated by a preocular dark brown stripe extending from the nasal scale, under the eye, and onto the anterior body. This stripe may continue as a series of spots onto the body. On the anterior body, the first two scale rows are the same yellow color as the ventral surface and form a ventrolateral stripe. A series of black marks occurs on some scales scattered on the sides of the body. An indistinct mid-line stripe occurs on the ventral surface.

Geographic distribution This species appears restricted to the Amazon Basin.

Comparison A vine snake with the combinations of the second pair of chin shields mostly separated by smaller scales, three upper labials bordering the orbit, four upper labials in contact with the primary temporal, and the eye diameter is about equal to the length of the internasal. Specimens from populations in Central America, Panama, and the western region have the second pair of chin shields in contact and two or three upper labials in contact with the primary temporal. Populations from Eastern Mexico have the second pair of chin shields in contact for most of their length and an eye diameter that is about 0.8 the length of the internasal. Those from northern South America also have three upper labials bording the orbit but have supraocualrs longer than the prefrontal.

Figures

Fig. 7 Specimen of O. aeneus (FMNH 64417) from Manaus, Amazonas, Brazil. This specimen was collected c. 518 km from the type locality

Fig. 3 Localities from which we obtained tissues for molecular work, other than the type locality represented by a black circle. Colors represent tissues of brown vine snakes from Central America (orange), Eastern Mexico (light blue), Panama (yellow), northern South America (purple), and the western region (light green); other taxa with molecular data represented are O. brevirostris (dark green), O. fulgidus (gray and

Fig. 4 Plot of discrimination analysis of sixteen morphological characters, showing clustering among geographically defined groups. Colors represent specimens from Central America (CA, orange), Central Brazil (CB, black stars), Eastern Mexico (EM, blue), northern South America (NSA, purple), Panama (P, yellow), and western region (WR, green). Colors correspond to those in Fig. 3