Gymnophthalmus marconaterai, Schargel, 2017

Schargel, Walter E., 2017, A new species of Gymnophthalmus (Squamata: Gymnophthalmidae) from sand dunes of the Llanos of Apure, Venezuela, Zootaxa 4318 (3), pp. 576-586 : 577-582

Gymnophthalmus marconaterai sp. nov.

( Figs. 1 , 2 )

Holotype. MCNG 2251 , an adult male, collected next to Troncal 2 road, between La Macanilla and Caño La Pica (approx. 6.933 N, 67.533 W; 50 m), Apure State, Venezuela, collected by J.E. García-Pérez and Andry Pereira, 10 October 2010.

Paratypes. 12 specimens, all from Apure State in Venezuela: MCNG 2252 (♀), MCNG 2253 (♀), MCNG 2254 (♂), MCNG 2255 (♀), MCNG 2256 (♂), MCNG 2257 (♂), MCNG 2258 (♂), UTA 63948 (♂), UTA 63949 (♂), UTA 63950 (♀): Caño La Pica , about 4 km west of Troncal 2 road (approx. 6.833 N, 67.533 W; 50 m), collected by J.E. García-Pérez, 13–16 August 1995 . MCNG 2262 (♂), MCNG 2263 (♀): sand dune next to Troncal 2 road, between San Juan de Payara and La Macanilla (approx. 7.133 N, 67.617 W; 50 m), collected by J.E. García- Pérez and W.E. Schargel, June 2002 .

Diagnosis. Gymnophthalmus marconaterai sp. nov. has 13 scales around midbody as opposed to 13–15 (typically 15) in G. cryptus , 15–17 in G. lineatus , and 16–19 in G. pleei Bocourt, 1881 . The new species further differs from G. cryptus and G. pleei (character states for both species in parenthesis) in having a white venter, sometimes suffused with orange yellow (dark venter or suffused with dark pigment), a salmon pink tail (blue in G. cryptus , brown or bronze in G. pleei ), and a well-defined lateral white stripe that extends posteriorly to the tail (absent in G. cryptus , vaguely defined and incomplete in G. pleei ). In G. marconaterai sp. nov. the white lateral stripe is about the same width as the dorsolateral white stripe, whereas in G. lineatus the lateral stripe is noticeably narrower than the dorsolateral stripe (about half the width). Among the species of Gymnophthalmus with 13 scales around midbody the new species differs from G. leucomystax Vanzolini & Carvalho, 1991 , G. speciosus sensu stricto (see discussion), G. underwoodi Grant, 1958 , and G. vanzoi Carvalho, 1998 (character states for these species in parenthesis), in having a well-defined and complete white, lateral stripe that extends from the ear opening to the tail (if present this stripe is vaguely defined, discontinuous and fades before the groin). Gymnophthalmus marconaterai sp. nov. further differs from these species as follow: from G. speciosus , G. underwood and G. vanzoi in having the medial surface of the belly and the ventral surfaces of manus, pes, and most of the underside of the tail white in preserved adults, as opposed to dark colored or overlaid with dark mottling in those areas in preserved adults. Finally, the new species further differs from G. leucomystax in having a salmon pink tail versus a grey tail. For further comparisons see the discussion section.

Description of the holotype. A small, slender lizard (SVL 37.1 mm) with short limbs (which do not overlap when adpressed against the body) and long tail (tail length 73.0 mm). Head small, 1.6 times longer than wide (head length 7.7 mm from tip of snout to posterior margin of tympanum; head width at widest point 4.9 mm), indistinct from neck, distinctly narrower than body (mid-body width 6.7 mm), somewhat depressed. Tip of snout round in dorsal view, acuminate in lateral view.

Rostral hexagonal, visible from above, 2.1 times as wide as deep. A large, roughly heptagonal frontonasal separates the nasals. A pair of hexagonal prefrontals in contact with each other medially, separates the frontonasal from the frontal. Frontal pentagonal (length 1.4 mm, width 0.9 mm) about the same size as a single prefrontal, 1.6 times longer than wide, 2.8 times longer than suture of prefrontals. Contact of prefrontal with loreal separates frontonasal from anterior supraciliary. Frontoparietals absent. A very large, roughly pentagonal interparietal (length 2.7 mm, width 2.0 mm) 1.4 times longer than wide, 1.9 longer than frontal. A pair of very large, roughly pentagonal, parietals, each slightly smaller than interparietal. A row of three occipitals; the medial one small, with pointed anterior margin, rounded posterior margin, in narrow contact with interparietal; laterals roughly heptagonal, with anterior margin slightly curved, transversely enlarged. One large, roughly hexagonal, supraocular on each side, in contact with supraciliaries, prefrontals, frontal, interparietal, parietals, and anteriormost upper temporal. Nostril in a single nasal, roughly in middle of scales. Loreal hexagonal, as high as long. A small frenocular, less than half the size of loreal. Preocular and subocular fused forming an elongated scale. Three postoculars, lowest one largest, about twice the size middle one, top one slightly smaller than middle one. Two supraciliaries, the anterior one very large, posterior one minute. Temporal region with medium to large imbricate scales. Two anterior temporals, in contact with postoculars, separating supralabials from supraoculars. Ear opening nearly round, surrounded dorsally and anteriorly by medium to large scales, the other two sides by small scales; tympanum visible. Eight supralabials, fourth and fifth longest, fifth centered below the eye, sixth extending higher than the rest. Eye large (1.7 mm long), slightly longer than eye-nostril distance (2.2 mm), eyelid absent, pupil round and large, spanning about half the area of the eye surface.

Mental trapezoidal with a convex anterior margin. A large pentagonal postmental in contact laterally with first three infralabials. Two pairs of large, somewhat imbricate chinshields, forming slanted median sutures that do not coincide with each other. Anterior pair trapezoidal (right) or pentagonal (left), laterally in contact with third and fourth infralabials; posterior pair transversely enlarged, about as long as first pair, with straight sides anteriorly and laterally but convexly curved posteriorly, laterally in contact with fourth and fifth infralabials. Six infralabials, third noticeably longer than rest, third and fourth below the eye.

Most head scales with a row of minute pits along their margins and also scattered elsewhere at low densities. All scales of head, body, and limbs smooth, except ventral surfaces of hand and feet.

Ten rows of transversely enlarged, imbricate gulars from the chinshields to the pectorals. Scales on the nape about the same size and shape as dorsal scales. Scales on the side of the neck, medium, imbricate, arranged in straight longitudinal and transversely oblique rows.

Scales on body imbricate, in 13 straight longitudinal rows around midbody; transversely the rows are oblique. Single vertebral row of medium size, roughly hexagonal to rhomboidal scales. Paravertebral scales transversely enlarged, roughly hexagonal. Single row of dorsolateral scales roughly rhomboidal, slightly smaller than paravertebral scales. Two longitudinal rows of lateral scales, roughly rhomboidal, slightly smaller than dorsolateral scales. Four straight, longitudinal rows of roughly hexagonal, imbricate ventral scales; the two medial rows transversely enlarged, lateral ventral rows distinctly smaller. There are 33 vertebral scales between the interparietal and the level of the posterior margin of the thighs. There are 24 scales in the midventral row between the pectorals (not included) and the precloacal plate. A large precloacal plate divided into four scales; one anterior and one posterior scale, subequal, in contact medially, separating the two lateral scales, roughly forming between the two the shape of an hourglass; lateral scales subequal, roughly rhomboidal, slightly larger than the anterior and posterior scales. Five femoral pores contained in contiguous scales on each side (ten total), separated medially by two scales anterior to the precloacal plate. Only the proximal two femoral pores on each side are conspicuous, the remaining three are small and somewhat difficult to discern.

Scales on and under the tail about the same size as dorsal scales, imbricate, rounded posteriorly, in straight longitudinal rows and oblique transverse rows, smooth in the anterior third, with low, sharp keels forming longitudinal ridges on the posterior two thirds.

Upper forelimbs covered with rounded, imbricate scales of variable size, but noticeably larger anteriorly. Lower forelimbs with large, slightly imbricate, roughly rectangular plates located anterolaterally; smaller, imbricate, roughly rhomboidal or hexagonal scales on other sides. Upper hind limbs with single row of generally large, imbricate, hexagonal plates anteriorly; dorsally and ventrally with smaller, roughly rhomboidal scales; posteriorly with tiny, roughly conical scales. Lower hind limbs with medium to small, imbricate, roughly rhomboidal scales. Four fingers (ancestral first finger absent); 13 single, obtusely keeled lamellae forming a serrated keel under the third finger (homologous with fourth in lizards with five fingers). Five toes; 18 lamellae under each fourth toe. Palms and soles with small, juxtaposed, tubercular (conical), granular scales, except for a few scales basal to the first and fifth toe, which tend to be roughly rectangular and slightly keeled, appearing as continuations of the toe lamellae.

Color in life and preservative. In life the dorsal surfaces of the head and body are pale brown, whereas the lateral surfaces are mostly dark brown. A series of pale (creamish white and white) and dark (black or dark brown) longitudinal stripes are arranged as follow: Three thin (less than one sixth the width of a dorsal scale), black, dashed and diffuse dorsal stripes extend from the occipital area to the tip of the tail; one of these stripes is located middorsally and the other two extend along the paravertebral scale rows. These three stripes fuse just past the base of the tail forming a single stripe. In the dorsolateral area there are, from dorsal to ventral direction, a very thin (less than one sixth the width of a dorsal scale), diffuse, creamish white stripe extends from the occipital area to about halfway on the tail; a thin (less than one fourth the width of a dorsal scale), solid anteriorly, dashed posteriorly, black stripe extends from prefrontrals to just past the halfway point of the tail; and a moderately wide (about a third of the width of a dorsal scale), solid, creamish white, stripe extends from the tip of the snout to about halfway on the tail. All three dorsolateral stripes are in contact with each other. On the sides, below the dorsolateral stripes, there is a wide (about the size of a dorsal scale), dark brown, lateral stripe that encompasses the eye and extends from the tip of the snout to about halfway point on the tail, where it diffuses and disappears. Below this dark brown stripe there is a moderately wide (about a third of the width of a dorsal scale), solid white, lateral stripe, that extends from the posterior margin of the ear opening to the tail, where it grades into the background color of the tail (see below); this white stripe passes just above the front limbs but it is briefly interrupted by the back limbs. Below this white stripe there is a thin (less than one fourth the width of a dorsal scale), somewhat diffuse, dark brown stripe that extends from just below the posterior margin of the ear opening to one leg distance on the tail; this stripe is briefly interrupted by both the front and back limbs. The top of the head has small, dark brown dashes, most of them obliquely oriented. On the sides of the head, anterior to the eye, the dark brown lateral stripe barely encroaches onto the supralabials; posterior to the eye the dark brown stripe extends to about the upper half of the scale row above the supralabials. Below the dark brown lateral stripe the background color of the head, including ventral surfaces, is white, but with bright orange yellow suffusions ventrally. Small brown spots are present on the posterior supralabials and infralabials. The background color of the throat and venter is white, heavily suffused with bright orange yellow. The dorsal and lateral color pattern of the tail is a continuation of the color pattern of the body but gradually fades posteriorly. The background coloration of the tail also gradually becomes pale salmon pink. The only marking left on the posterior half of the tail is a diffuse, irregular, dark brown, supracaudal longitudinal stripe that extends to the tip of the tail. The background coloration of the underside of the tail is white but gradually becomes suffused with orange posteriorly. The limbs have a marbled pattern of white, pale and dark brown dorsally, fading towards the ventral surfaces, which are white with vague pale brown suffusions. In preservative the coloration is essentially the same with the most notable exception being that the bright colors (yellow and pink) of the venter and tail have faded out.

Variation. The type series includes eight males and five females. The largest male (UTA 63949) and female (UTA 63950) are 39.4 mm and 36.2 mm in SVL, respectively. The smallest specimen (MCNG 2254) is a male, 29.1 mm in SVL. Variable meristic characters have the following ranges: supralabials seven or eight, vertebral scales between the interparietal and the posterior margin of thighs 31–36, midventral scales between the pectorals and the precloacal plate 21–25, lamellae under third finger 11–14, lamellae under fourth toe 16–18. Individual variation in relevant morphometric and meristic characters is reported in Table 1. In specimens with the tail regenerated, scales on and under the regenerated part are elongate, hexagonal, keeled, in transverse and in longitudinal rows. There is little variation in color pattern and coloration. The holotype was the only specimen with noticeable yellow suffusions on the venter. All other specimens had a creamish white venter in life.

Distribution and natural history. We collected individuals of the new species in three localities in the area of eolic plains that contain sand dunes in Apure State ( Fig. 3 ; see Schargel 2015). The holotype was found in the leaf litter under a Bowdichia tree and is the only specimen not collected directly on a sand dune. Most specimens were collected or observed in a group of sand dune islets located within the La Pica River. These dunes are protected from the periodic fires in the region by the river waters, and from flooding in the rainy season because they are elevated. The dunes in the La Pica River bear peculiar vegetation ( Fig. 4 ) that includes cacti ( Cereus hexagonus ; we have not observed any cacti in other sand dunes in the region), clusters of small to medium size trees that frequently include Byrsonima sp., and Trachypogon thickets in areas with no trees. Most specimens were found foraging in the leaf litter and under the shade provided by trees. Individuals were active throughout the day when sunny conditions prevailed. A few individuals were also observed quickly crossing the bare sand between Trachypogon thickets. Gymnophthalmus marconaterai sp. nov. has the ability to quickly bury under sand as we observed when attempting to collect individuals on bare sand. We found several other sympatric species of lizards in these dunes including Ameiva praesignis Baird & Girard , Anolis auratus Daudin , Cnemidophorus gramivagus McCrystal & Dixon , Kentropyx striata Daudin , Phyllodactylus ventralis O’Shaughnessy , Tropidurus hispidus Spix , and Tupinambis cryptus Muphy, Jowers, Lehtinen, Charles, Colli, Peres, Hendry & Pyron. A couple other individuals of G. marconaterai sp. nov. were collected from another sand dune area on the side of the road (Troncal 2) just north of the Capanaparo River. These specimens were also collected in the leaf litter under trees, suggesting that this is the preferred microhabitat for this species in the area. We have never observed specimens on active sand dunes that are devoid of vegetation. About half of all specimens collected had broken or regenerated tails, suggesting that tail autotomy is an important antipredator mechanism in this species.

Etymology. The new species is named after our late friend Marco Antonio Natera Mumaw. Marco was a young and enthusiastic herpetologist with a keen interest in snake biology and conservation. He was the founder of the herpetological collection at the Universidad Nacional Experimental Rómulo Gallegos and led many initiatives to educate people about protecting snakes.

Figures

FIGURE 1. Sexual species of Gymnophthalmus with 13 dorsal scales around midbody from South America: holotype of Gymnophthalmus marconaterai sp. nov. (top left, photo by JEGP); G. cf. speciosus (top right, photo by JEGP) from Biruaca, Apure, Venezuela; G. leucomystax (bottom left, photo by M. Teixeira Junior) from Roraima, Brazil; G. vanzoi (bottom right, photo by M. Teixeira Junior) from Roraima, Brazil.

FIGURE 2. Illustrations of the head of Gymnophthalmus marconaterai sp. nov. (UTA 63949) in dorsal (top), lateral (middle), and ventral (bottom) views.

FIGURE 3. Map of the area with sand dunes in Apure State in Venezuela showing the collecting localities for Gymnophthalmus marconaterai sp. nov: (1) road between San Juan de Payara and La Macanilla, (2) road between La Macanilla and Caño La Pica, and (3) Caño La Pica. Dashed line represents “ Troncal 2 ” road.

FIGURE 4. Habitat of Gymnophthalmus marconaterai sp. nov. from the sand dunes of Caño La Pica (Photo by JEGP).