Erythrolamprus pseudoreginae, Murphy, John C., Braswell, Alvin L., Charles, Stevland P., Auguste, Renoir J., Rivas, Gilson A., orzee, Amael, Lehtinen, Richard M. & Jowers, Michael J., 2019

Murphy, John C., Braswell, Alvin L., Charles, Stevland P., Auguste, Renoir J., Rivas, Gilson A., orzee, Amael, Lehtinen, Richard M. & Jowers, Michael J., 2019, A new species of Erythrolamprus from the oceanic island of Tobago (Squamata, Dipsadidae), ZooKeys 817, pp. 131-157 : 137-141

Erythrolamprus pseudoreginae sp. n. Figures 2D, 3A, 6

Liophis sp. Hardy 1982: 86.

Liophis reginae [ssp.] Dixon 1983b: 12.

Material.

Holotype. UWIZM.2016.22.45 collected 13 June 2016 by Alvin L. Braswell and Renoir J. Auguste on Gilpin Trace Trail, 8.5 km NNW Roxborough, St. John, Tobago (~ 11°16'55"N; 60°37'12"W, about 493 m ASL) at 0900 hrs. Paratypes. TOBAGO: St John: FLMNH 91621 Gilpin Trace Trail, 5.3 mi NNW Roxborough, 11°16'N, 60°37'W collected on 17 July by Kurt Auffenberg. USNM 228069 south of Charlotteville, at first creek crossing on Pigeon Peak Trace 11°17'N, 60°36'W collected 12 May 1979 at (14:00 hrs) by Dave Stephens; USNM 325089 NW of Roxborough on Gilpin Trace, ca. 0.5 mi from its junction with Roxborough-Bloody Bay Road, collected 11 November 1992; USNM 539191 approx. 6 km (airline) NNW of Roxborough, 0.5 mi from upper entrance of Gilpin Trace and Roxborough - Parlatuvier Road, 11°17'N, 60°35'W collected 11 July 2000.

Diagnosis.

Ventrals 143-154; subcaudals 76-79; second pair of chin shields longest; some anterior dorsal scales have an apical pit; lateral stripe on scale rows 3 –4– 5, dark stripe (row 3) and a pale stripe (rows 4-5) on posterior body and tail, the black stripe continues to the forebody as a series of black spots on scale row three; and the ventral surface has scattered flecks of pigment toward mid-body. Otherwise, the belly is uniform cream with fine speckling in preserved material, and red in life, tail uniform cream in preservative, red in life.

Description of the holotype.

UWIZM.2016.22.45, an adult male, 525 mm total length, 148 mm tail; tail 28% of SVL. Rostral barely visible from above, broader than tall; internasals paired, shorter than prefrontal; frontal pentagonal; parietals longer than frontal; four post parietals; nasal divided, first lobe does contact the second labial; loreal subrectangular, higher than long, contacts upper labials 2-3; preocular single, T-shaped, contacts upper labials 3-4; postoculars 2/2, upper largest; temporals 1+2, primary temporal contacts upper labials 6 –7/6– 7; upper labials 8/8; 4-5 in orbit; lower labials 4/5 contact anterior chin shields, total of nine in contact with both pairs; lower labials 9/10; three gular scales; dorsal scales are smooth, some have a single apical pit, they are in 17 rows at mid body and reduced to 15 rows anterior to the cloaca; 146 ventrals; 77 subcaudals.

In life the crown is dark moss green with black spots, the upper labials are cream, with a dark stripe on the upper edge that runs from nasal to orbit, and widens posteriorly onto the temporals. Dorsal spots on scale rows 2-3 about two ventrals apart, start above the 12th ventral, and coalesce into a stripe at about the 96th ventral and extend posteriorly to the tip of the tail; lateral stripe mostly on scale row three on body, goes onto scale row one on tail. About one-third down the body, about ventral 40, scale rows 1−4 blue-gray, row five is brown, row six and above blue-gray; except for the mossy green on the anteriormost dorsal surface for about 40 ventrals. Ventral surface mostly uniform yellow to orange with light mottling starting about the 50th ventral; tail has a mid-line zigzag stripe.

Variation: The smallest specimen measured 347 mm SVL with a 129 mm tail; the largest specimen 420 mm SVL with a 119 mm damaged tail. Dorsal scale rows 17 –17– 15. Ventrals range from 143-154 (n = 5, X = 147.5, SD = 3.35); subcaudals 76-79 (n = 2, X = 77.5, SD = 1.5). Upper labials eight or nine, 2-3 contact loreal, 4-5 border the orbit (one specimen has 5-6 bordering the orbit on one side), the tallest can be seventh, (or eight if nine labials are present); the sixth labial is the largest in the area. Loreal is quadrangular to pentagonal. Lower labials 9-10; first four or five contact the anterior chin shields. Longest pair of chin shields is the second. Eye diameter is greater than eye-nostril distance. The dark posterior lateral stripe is usually on scale rows 2 –3– 4, but one specimen has it on scale rows 2-3 only.

Color in life. The following is based on the holotype (Figure 6) and a color photograph in Brown (2013). Crown and face olive brown, upper labials white, a short black subocular stripe extends from the nasal scale under the eye and posteriorly to the last labial. Immediately behind the head, the interstitial skin is yellow; dorsum brown with an indistinct vertebral stripe and scales partially edged with black pigment most obvious on posterior two-thirds of the body. First three scale rows are blue-gray and separated from brown dorsum by a row of black spots.

Color in alcohol. Head, body, and tail dark blue to brown with a black stripe on the posterior lateral body that becomes a series of dark spots extending anteriorly on the body. The belly is a uniform cream with fine speckling of pigment.

Comparisons.

Erythrolamprus pseudoreginae sp. n. differs from E. zweifeli in the presence of apical pits on some dorsal scales, an almost uniform yellow to red venter, and a dark stripe on the posterior body on scale rows 3-4 bordered above by a pale stripe on scale row five. The new species lacks the well-defined postocular stripe that runs from the postocular scales across the temporals to a point just above the rictus in most E. zweifeli . In E. zweifeli the postocular stripe may also have a pale dorsal border.

Erythrolamprus pseudoreginae sp. n. differs from all populations of E. epinephalus in having more than 75 subcaudal scales, except for some Venezuelan and Colombian populations. The E. epinephalus populations with more than 75 subcaudals have a dorsal or ventral pattern that includes transverse bars, black checks, or a pattern with irregular black spots on the outer edges of the ventral scales that may extend onto the first row of dorsal scales ( Dixon 1983a, Escalona 2017).

The new species differs from Erythrolamprus reginae in having a uniform venter ( E. reginae ) has yellow to orange venter with black checks, and a dark stripe on the last fourth of the body on scale rows 3-4 which is not bordered by a pale stripe. Erythrolamprus pseudoreginae sp. n. has uniform yellow to red ventral surface and a very distinctive, pale posterior lateral stripe on row five above the black stripe on rows 3-4 that extends anteriorly as a row of dark spots. Erythrolamprus reginae has fewer ventrals and a lower mean ventral count than E. pseudoreginae sp. n.

The pattern will readily distinguish it from the two coral snake mimics ( Erythrolamprus aesculapii and E. bizona ) which are on Trinidad but not Tobago. The endemic Tobago Red Snake, E. ocellatus , has a bright red dorsum with black ocelli. The semi-aquatic Erythrolamprus cobellus has a uniform dark green or black dorsum and is known from Trinidad but not Tobago. The absence of a black stripe five scale rows wide on the vertebral line separates it from Shaw’s Black Back Snake, E. melanotus , a species known from both islands.

Distribution.

It occurs in northeastern Tobago and appears to be restricted to the forested ravines along the crest of the Main Ridge (Fig. 4). Tobago’s Main Ridge is about 16 km long and covered with lower montane rain forest on schist soil above 224 m ASL. The ridge crest reaches elevations of 487-576 m ASL and forms steep terrain with deep gullies and fast-moving streams. The area receives about 318 cm of rainfall per year, and no month receives less than 10 cm (Beard, 1944). Tobago’s Main Ridge Forest Reserve is the oldest protected forest in the Western Hemisphere (since April 1776) and encompasses 3958 hectares. At this writing, five specimens of Erythrolamprus pseudoreginae sp. n. are known, all of which came from the northeast end of the Main Ridge. The locality and elevation data available suggest it occurs within an area of about 400 ha at elevations between 430-500 m ASL. Three types of rainforest occur on Tobago: lowland rainforest covers 4,844 ha, lower montane rainforest covers 4,566 ha, and xerophytic rainforest covers 937 ha ( Helmer et al. 2012). All of the localities for E. pseudoreginae sp. n. fall within the lower montane rainforest, suggesting its maximum area of occupancy may be 4,566 ha, if it is restricted to that forest type.

Natural History.

Erythrolamprus pseudoreginae sp. n. is diurnal, all of the specimens with time of collection data were found in the morning or afternoon. Nothing is known about the diet and reproduction of this snake. Its close relatives have been reported to eat anurans, and it likely preys upon small ground-dwelling frogs.

Conservation.

Given the restricted distribution of this snake as well as the fact that most, if not all, of its distribution lies within the oldest protected forests in the Western Hemisphere it may be assumed that it is well protected. However, as the climate changes the microclimate found in the lowland montane rainforest may be expected to change and potentially make the local environment inhospitable for this species and the other endemic taxa found here.

Etymology.

The epithet pseudoreginae was chosen because prior investigators considered this snake to be Liophis reginae . We suggest Tobago Stream Snake as the common English name for this snake.