Oxybelis koehleri, Jadin & Blair & Orlofske & Jowers & Rivas & Vitt & Ray & Smith & Murphy, 2020

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 : 733-736

Oxybelis koehleri sp. nov.

Köhler’ s Vine Snake

Oxybelis aeneus – Duméril et al. 1854: 819

Dryophis acuminata – Günther 1858: 156

Oxybelis acuminata – Boulenger 1896: 192

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

Holotype UTA R-46846 ( ENS 9858 ), a female from Guatemala: El Arenal (circa 560 m, 14° 53′ 1.788″ N, 89° 46′ 31.799″ W) of the Municipio Cabañas in the Department of Zacapa. Collected by a local between Feb and May 1998, preserved 24 Aug 1998.

Paratypes UTA R-44838 Nicaragua: Jinotega, El Paraiso Km 152.5, carretera Jinotega-Matagalpa , 1490 m ; UTA R-46865 Honduras: Comayagua, Playitos: Aldea “ Lo de Reina ”, 785 m. UTA R-53176–77 Honduras: Gracias a Dios, Mocorón, 30–50 m.

Diagnosis Using data from our examination of specimens from Central America, we constructed the following description for Oxybelis koehleri . A vine snake with (1) three upper labials (4–5–6) bordering the orbit; (2) black spots or bars on anterior body, brown uniform brown with little black pigment; (3) labials white and underside of head red–brown with a medial red–brown stripe in females; (4) eye diameter greater than preocular length; (5) second pair of chin shields in contact for most of their length; (6) nine upper labials, three located behind the orbit; (7) snout from above is narrow, tapered, and rounded (snout type A); (8) supraocular is longer than the prefrontal; (9) last upper labial and primary temporal about the same length; and (11) second upper labial does not contact the preocular. Description of holotype ( UTA R-46846, Fig. 8 ) A female, total length 905 mm, tail length 439 mm. Rostral broader than tall; barely visible from above; upper labials 8 (5 + 6 fused)/9; internasals paired, extending past the posterior border of the first upper labial but not the nasal, which is longer than both; prefrontals paired, contact upper labials 2–3; triangular frontal and supraoculars elongated and circa 8 mm long, paired parietals slightly longer circa 9 mm; supraoculars and parietals, contact upper postocular; postoculars 2/2, upper larger; upper labials 3–4 contact the preocular; 4–5–6 are in the orbit (4 + 5 on left side because of fusing); 7–8–9 contact the primary temporal; 9 interrictals; one preocular less than the diameter of the eye; lower labials 10/10, first four contact the first pair of chin shields; second pair of chin shields longest; four paired gulars. Dorsal scales smooth in 17–17–13 rows. Ventrals 198, 119 divided subcaudals, anal plate divided.

Variation Rostral is not visible from above and followed by nine plate-like scales on the crown: a pair of internasals, a pair of prefrontals, the frontal, two larger supraoculars, and a pair of parietals. Preoculars extend slightly on to the crown between the prefrontals and supraoculars. The internasals are 75% (r = 0.63–1.0) of the prefrontal length. Average eye diameter is 1.19 (r = 0.83–1.53) the preocular length. In profile, the nasal scale is elongate extending from the edge of the rostral, beyond the preocular scale is short and less than the diameter of the eye. Scales bordering the orbit are the preocular, the supraocular, two small postoculars, and upper labials 4–5–6. Primary temporal contacts both postoculars, the parietal, and two secondary temporals, as well as upper labials 6–7–8–9. Upper labials number nine (rarely eight or ten). The shortest upper labial can be the first or the eighth. The last (usually the ninth) upper labial is the longest. Upper labials 1–2 contact the nasal, 2–3 contact the prefrontal–loreal, 3–4 contact the preocular. Lower labials vary from eight through 10, usually 9; 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; the second pair are in contact for most of their length. Dorsal scales are in 17–17–13 rows.

In males, total length ranged from 1135 to 1432 mm (n = 6, x = 1329.83, SD = 106.68), SVL 673–835 mm (n = 7, x = 783.71, SD = 62.55), tail lengths 462–600 mm (n = 7, x = 554.0, SD = 47.75), tail/SVL ratios (n = 7, r = 0.67–0.79, x = 0.71, SD = 0.04). In females, total lengths ranged from 1137 to 1300 mm (n = 8, x = 1221.43, SD = 63.72); tails ranged from 425 to 527 mm (n = 7, x = 478.14, SD = 31.22). Tail/ SVL ratios in females 0.53–0.73, x = 0.65, SD = 0.06.

Ventrals in males vary from 176 to 191 (n = 7, x = 183.83, SD = 4.88); ventrals in females vary from 184 to 191 (n = 7, x = 187.57, SD = 2.26). Subcaudals in males vary from 164 to 186 (n = 5, x = 177, SD = 8.12); in females, subcaudals vary from 176 to 189 (n = 5, x = 184.8, SD = 5.91).

Coloration and pattern ( Fig. 9 ) Head usually a uniform brown (it may have some darker pigmented spots), body brown with light mottling and some dark spots anteriorly, posteriorly indistinct transverse blotches that are wide on the vertebral line and narrow laterally; upper labials cream to white and separated from the brown by a black stripe on the dorsal edge of the second labial that extends past the eye to the last labial; lower labials have some red–brown pigmentation; ventral surface of head tan laterally with a red–brown medial stripe that extends from the mental onto the first 15 ventrals. Longitudinal ventral stripes absent. All adult females we have examined (including sequenced material) have a red–orange stripe on the underside of the head and onto the first 12 anterior ventrals, and the coloration is present as spots on some upper labial scales.

In alcohol, (FMNH 27050) the coloration and pattern are much reduced. The head is gray–brown, the labials are white, and the marking on the lower labials, along with the reddishbrown chin, is usually absent. The ventral side of the head is uniform cream. The dorsum is gray with black lateral spots where the transverse blotches were in life. The ventrals are pale with dense mottling.

Geographic distribution This species occurs from Guatemala to Costa Rica in Central America.

Etymology The specific epithet is a patronym honoring Gunther Köhler, who has contributed greatly to our knowledge on the systematics and natural history of amphibians and reptiles, with particularly impressive contributions in Central America. Dr. Köhler has published more than 200 scientific articles and numerous books in English, Spanish, and German, greatly increasing scientific and public access to Central American herpetology.

Comparison A vine snake with nine upper labials, three of which border the orbit, an eye diameter that is about equal to the length of the internasal, three upper labials in contact with the primary temporal, and the second pair of chin shields in contact for most of their length. Specimens of O. aeneus and those from northern South America have the second pair of chin shields separated for most of their length. Specimens from the western region have an eye diameter that is less than the length of the internasals while those from Panama usually have eight upper labials.

Oxybelis microphthalmus Barbour and Amaral, 1926 Thrornscrub Vine Snake

Dryinus aeneus – Wagler, 1824

Oxybelis aeneus – Duméril et al. 1854: 819

Dryophis acuminata – Günther 1858: 156

Oxybelis acuminata – Boulenger 1896: 192

Oxybelis microphthalmus – Barbour and Amaral 1926 Oxybelis aeneus auratus – Bogert and Oliver 1945: 381 Oxybelis aeneus auratus – Zweifel and Norris 1955 Oxybelis aeneus – Keiser 1974: 7

Holotype MCZ 22417 from Calabasas Canyon , Arizona (circa 31° 28′ N, 110° 58′ W) designated by Barbour and Amaral 1926: 80

Diagnosis Using data from our examination of specimens from the western region, we constructed the following description for Oxybelis microphthalmus . A vine snake with (1) three upper labials (4–5–6) bordering the orbit; (2) black spots or bars on anterior body, dorsum mostly uniform brown with little black pigment; there are small scattered black spots on the dorsum; (3) venter is finely mottled and it can have a dark lateral stripe on the outer edge of each ventral, and a pale mid-ventral stripe; (4) eye diameter shorter than preocular; (5) second pair of chin shields in contact for most of their length; (6) eight upper labials in most Arizona and Sonora specimens, nine upper labials in other Mexican populations, but all tend to have three labials behind orbit; (7) snout from above is narrow, tapered, and rounded at the tip (snout type A); (8) supraoculars are longer than the prefrontals; (9) lower surface of the head is uniform white or yellow in color (not mottled); (10) last upper labial shorter than primary temporal; and (11) second upper labial does not contact the preocular.

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. 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. Eye diameter/internasal ratio in this species averages 0.82 (n = 34, r = 0.58–0.97, SD = 0.10). Preocular scale is long and greater in length than the diameter of the eye. Scales bordering the orbit are the preocular, the supraocular, two small postoculars, and upper labials 4–5–6 (rarely 5–6–7). Primary temporal contacts both postoculars, the parietal, and two secondary temporals, upper labials 7–8 or 7–8–9 or 6–7–8–9. Upper labials vary from 8 to 10. Of 66 sides of heads examined, 30 (45%) had 8 upper labials; 30 (45%) had 9 upper labials, and six (10%) had 10 upper labials. The shortest upper labial can be the first or the fifth. The longest upper labial is the 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 sixth or seventh. Lower labials range from 8 to 10, (usually 9). The first four labials (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%) of 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 with the posterior scales being weekly keeled.

Variation Geographic variation in the upper labial and ventral counts exists. Arizona (USA) and Sonoran ( Mexico) populations tend to have eight upper labials, while Oaxaca and Guerrero ( Mexico) populations have nine upper labials. Ventral counts in Arizona and Sonora tend to be at the high end of the range; populations to the south have lower numbers.

In males, total length varies from 1197 to 1337 mm (n = 10, x = 1262.13, SD = 73.17), SVL varies from 713 to 834 mm (n = 10, x = 766.68, SD = 46.37), tail lengths vary from 484 to 538 mm (n = 8, x = 502.21, SD = 35.99); tail/SVL ratios vary from 0.63 to 0.74 (n = 8, x = 0.68, SD = 0.03). Female total lengths vary from 667 to 1407 mm (n = 14, x = 1238.0, SD = 195.99); tails vary from 250 to 544 mm (n = 12, x = 475.83, SD = 107.19). Tail/SVL ratios in females vary from 0.60 to 0.72 (x = 0.64, SD = 0.04).

Ventrals in males vary from 184 to 202 (n = 14, x = 192.0, SD = 5.92); ventrals in females vary from 184 to 204 (n = 12, x = 193.58, SD = 5.2). Subcaudals in males vary from 163 to 175 (n = 5, x = 168.4, SD = 4.18); in females, subcaudals vary from 170 to 183 (n = 7, x = 177.2, SD = 4.22).

Coloration and pattern The crown of the head and upper face are brown to tan ( Fig. 10 ). 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. The first two scale rows on the anterior body are the same yellow color as the ventral surface, and form a ventrolateral stripe. At mid-body, the first four dorsal scale rows and the lower half of the fifth scale row are mottled heavily with dark pigment; the upper half or row five and rows 6–8 lack the dense mottling, giving the overall impression of a series of lateral stripes. On the ventral surface is an indistinct mid-ventral stripe.

In alcohol (UAZ 39545), the coloration has often faded but the elements of the pattern and the colors are still detectable.

Geographic distribution Southeastern Arizona southward to Oaxaca, Mexico

Comparison A vine snake with eight (Arizona and Sonora) or nine (remainder of distribution in Mexico) upper labials with three behind the orbit, an eye diameter that is about 0.8 of the internasal (no other species of Oxybelis has an eye diameter this small). It also has two or three upper labials in contact with the primary temporal and the second pair of chin shields are in contact for most of their length. Oxybelis aeneus and those from northern South America have the second pair of chin shields separated for most of their length. Oxybelis koehleri and those from Panama usually have two upper labials behind the orbit.

Figures

Fig. 8 Holotype of Oxybelis koehleri sp. nov., UTA R-46846 preserved; a dorsal; b top of the head; c profile; d ventral views. Scale bar = 1 cm

Fig. 9 Oxybelis koehleri sp. nov. in life. a Mocorón, Gracias a Dios, Honduras (C.J. Franklin); b Santa Rosa, Costa Rica (L. Porras)

Fig. 10 Oxybelis microphthalmus in-life. a and b show the profiles while c shows the gaping mouth defensive behavior. Photograph a by JCM and b and c by J. Reyes- Velasco