Oxybelis inkaterra, Jadin & Jowers & Orlofske & Duellman & Christopher Blair & Murphy, 2021

Jadin, Robert C., Jowers, Michael J., Orlofske, Sarah A., Duellman, William E., Christopher Blair, & Murphy, John C., 2021, A new vine snake (Reptilia, Colubridae, Oxybelis) from Peru and redescription of O. acuminatus, Evolutionary Systematics 5 (1), pp. 1-12 : 1

Oxybelis inkaterra sp. nov. Figs 5 , 6 , 7 , 8 , 9; Suggested English Name: Inkaterra Vine Snake; Suggested Spanish Name: Inkaterra Serpiente de vid

Oxybelis aeneus - Keiser, 1974:7;

Oxybelis aeneus Duellman 2005: 363, pl 205 has a photograph of a live specimen

Oxybelis aeneus Jadin et al. 2020: Fig. 1 . has a photograph of a live specimen.

Holotype.

KU 220196 (Figs 5 , 6 ), from Peru, Madre de Dios: Cusco Amazónico (now Reserva Amazónica), Río Madre de Dios, c. 15 km E Puerto Maldonado, 200 m, 12°34'59"S, 69°4'59"W; collected by William E. Duellman (WED 59561), 21 December 1991.

Paratypes. KU 214887, Peru, Madre de Dios: Cusco Amazónico, Río Madre de Dios, c. 15 km E Puerto Maldonado, 200 m, 12°34'59.88"S, 69°4'59.879"W; collected by Erik R. Wild (Field number WED 59004), 23 December 1989; ZMH R01702, Peru, Huánuco: Pachitea, Panguana Biological Fieldstation, Rio Yuyapichis [= Rio Llullapichis], 260 m, approx. 9°41'S, 74°57'W, collected by János Regös July 1980.

Other material examined.

FMNH 56141, from Peru, Loreto, Río Ucayali: Yarinacocha (c. 13°51'S, 71°1'W), collected by J.M. Schunke, 05 Sep 1946 . FMNH 40085 (female), from the Madre de Dios area of Peru (no specific locality). ZMH R01611 , Peru, Huánuco: Pachitea , Panguana Biological Fieldstation, Rio Yuyapichis [= Rio Llullapichis], 260 m, approx. 9°35'S, 74°56'W, collected by Carlos Vasquez Modena 1980.

Like other members of the Oxybelis aeneus complex O. inkaterra has an elongated head and body, 8-9 upper labials, four lower labials contacting the first pair of chin shields, 173-205 ventrals and 158-203 subcaudals; a divided anal plate, dorsal scales in 17-17-13 rows, and undivided hemipenes.

Diagnosis.

A vine snake with (1) three upper labials (4-5-6) bordering the orbit; (2) numerous bold black bars and spots present on the body; (3) ventral surface mottled with dense black spots; (4) preocular shorter than eye diameter; (5) second pair of chin shields separated by smaller scales posteriorly; (6) nine upper labials, three located behind the orbit; (7) snout from above relatively broad, tapered, and flat rostrum; (8) supraocular and prefrontal are about the same length; (9) last upper labial about same length as primary temporal; (10) much of the lower surface of the head infused with black pigment; (11) second upper labial not in contact with preocular.

Comparison.

Oxybelis inkaterra can be distinguished from the seven other members of the Oxybelis aeneus complex by the presence of, upper labials three and four are in contact the preocular; a head with an irregular, darkly pigmented ventral surface with pale spots; and eyespot markings on the posterior ventral surface of the body and tail; the snout of O. inkaterra is also relatively short and broad compared to other species in the Oxybelis aeneus complex (Fig. 7 ); the lack the brown-gray dorsal coloration seen in the other members of the complex. The dorsum is instead a dirty cream with black flecking (Figs 6 , 8 ).

Description of the holotype.

A male with everted hemipenes (Fig. 6 ), SVL 732 mm, tail length 498 mm. Rostral broader than high, barely visible from above; upper labials 9/9; internasals paired, not extending past the posterior border of the first upper labial; prefrontals paired, in contact with upper labials 2 and 3; frontal, paired parietals, and supraoculars elongated and about 6 mm long, and in contact with supraoculars and upper postocular; postoculars 2/2; upper labials in contact with the preocular; 4-5-6 enter the orbit; 7-8-9 contact the primary temporal; 9 interrictals; one preocular less than the diameter of the eye; lower labials 10/10, first four in contact with the first pair of chin shields; second pair of chin shields longest; five paired gulars. Dorsal scales smooth in 17-17-13 rows. Ventrals 182; 165 divided subcaudals; anal plate divided.

In alcohol.

Top of the head is brown with dark brown to black mottling (Figs 7 , 8 ); black spot on posterior edge of nasal, and on preocular; black mottling on temporals forming an irregular postocular stripe that extends to second or third ventral; upper labials with mottling on borders, lower labials heavily mottled; mental, first pair of lower labials, and chin shields black with white spots; dorsal scales mottled with black and brown pigment in all rows; on anterior third of the body, some scales have heavy black pigment on their borders and form about 48 irregular transverse bands; anterior ventrals heavily mottled becoming fine stippling posteriorly; some ventrals mottled with scattered black spots anteriorly; posteriorly, these spots encircled with white pigment to form eye spot-like markings near the vent; some of these markings also occur on the ventral and lateral portions of the tail.

Coloration of the holotype in life

(Fig. 5 ). Field notes by W.E. Duellman on 21 December 1991: Dorsum and venter grayish tan with dark brown flecks and streaks. Top of head brown; lateral stripe on head dark brown, bordered below by white. Iris cream with horizontal dark brown stripe. Lining of mouth and throat black.

Variation.

Whereas surrounding the black spots was not as pronounced in smaller individuals, KU 220196 has the first 33 ventral scales almost completely black (in preservative), but the stripes are still visible (Fig. 6 ). The black pigment extends onto the chin shields in varying amounts. The largest female was 1075 mm in total length; the largest male was 1278 mm. Two females had SVLs of 484 and 660 mm (x- = 572 mm SD = 88.0) with tails that were 0.62 and 0.63 of the SVL (x- =358.5, SD = 56.50). Two females (FMNH 40085, 56141) (had 184 and 191 ventrals (x- = 187.5, SD = 1.5). Eight upper labials, with 4-5-6 bordering the orbit. Usually 8-9 (nine on one side) lower labials, with four (usually) at first chin shield.

Distribution.

This species occurs in the Amazonian rainforest of Peru in the departments of Huánuco, Loreto, and Madre de Dios. It is likely the species also occurs in Ucayali between these departments and possibly adjacent Bolivia, Brazil, and Colombia.

Ecology.

At Reserva Amazónica, Oxybelis inkaterra is found in the dense vegetation on the bank of the Río Madre de Dios and in an adjacent clearing. The steep riverbank has vegetation unlike that of the adjacent rainforest. There are shrubby plants and no canopy; adjacent to the river are stands of the cane-like Gynerium saggitatum ( Ponaceae ). Oxybelis inkaterra is a diurnal arboreal snake, which, if like other members of the genus, has a fondness for small lizards. In the scrub forest adjacent to the river two species, Gonatodes humeralis ( Sphaerodactylidae ) and Anolis fuscoauratus ( Dactyloidae ), inhabit the scrub and probably are primary prey of the vine snake.

Field notes.

KU 220196, weight 30.5 g, caught on the ground in camp during the day. Dorsum and venter grayish tan with dark brown flecks and streaks. Top of head brown; lateral stripe on head dark brown, bordered below by white. Iris cream with horizontal dark brown stripe. Lining of mouth and throat black. KU 214887, caught in bush 1.5 m above ground by day edge of river in camp. Mass 15 g, 895 mm TL.

Etymology.

The specific epithet honors the ecotourism company Inkaterra (https://www.inkaterra.com/) and its non-profit NGO counterpart Inkaterra Asociación. These two institutions started in 1975 and 1978, respectively, were founded by José E. Koechlin von Stein to promote education and conservation of Peruvian culture and ecosystems. Inkaterra and Mr. Koechlin have been recognized numerous times with awards and accolades for providing sustainable ecotourism and research opportunities for scientists. The type locality, Cusco Amazónico (now Reserva Amazónica), is owned and operated by Inkaterra and is the site of one of the most thoroughly studied areas in the Neotropics, particularly for amphibian and reptile natural history (e.g. Duellman, 2005; Orlofske et al. 2012).

Notes on potential eyespots.

Anti-predator adaptations in snakes are numerous and diurnal species can be expected to use visual coloration and behaviors to deter predators (Green, 1997). Eyespots are circular markings, often with concentric rings and conspicuous colors, that occur in many animals. They have been hypothesized to work as a way to startle or intimidate predators or they may work by being highly salient stimuli that promote sensory overload, biases, or neophobic reactions ( Stevens and Ruxron 2014). Few snakes have been reported to have eyespots but Oxybelis inkaterra appears to be an exception and does exhibit ventral eyespots (Fig. 9 ). Although the markings are quite variable in size and definition, they are best developed in specimen FMNH 56141 from Yarinacocha, Peru. Given the absence of information in terms of how the snake uses these markings it is entirely possible that they simply make the snake more cryptic in its arboreal environment. However, the placement of the eyespots on the posterior ventral side of the body and on the tail suggests that they may be displayed in response to a predator.

Figures

Figure 1. Illustration reproduced from Bell 1825 of Dryinus auratus from " Mexico ".

Figure 5. Holotype of Oxybelis inkaterra sp. nov., KU 220196 in life from Reserva Amazonica, formerly Cusco Amazonico, Peru (W. E. Duellman).

Figure 6. Holotype of Oxybelis inkaterra sp. nov., KU 220196 preserved. A, Dorsal whole specimen; B, ventral whole specimen views; C, top of the head; D, profile. Scale bar: 1 cm.

Figure 7. A comparison between the snout shapes of Oxybelis aeneus (FMNH 64417) (top) and O. inkaterra (FMNH 56141) (bottom) (JCM).

Figure 8. Referred specimen of Oxybelis inkaterra sp. nov., FMNH 56141 from Peru, Loreto, Rio Ucayali, Yarinacocha. A, profile; B, top of the head; C, bottom of the head.

Figure 9. Referred specimen of Oxybelis inkaterra sp. nov., FMNH 56141 displaying eyespots on posterior ventral scales (left) and on subcaudal scales (right).