Riolama grandis, 2020

RIOLAMA GRANDIS RECODER ET AL. View in CoL , SP. NOV.

( FIGS 7–9)

Riolama View in CoL sp. nov. a, McDiarmid et al., 1988: 669. Riolama sp. A ( Neblina ), McDiarmid & Donnelly, 2005: 515, 540; Kok, 2015: 501, fig. 7.

LSID: urn:lsid:zoobank.org:act:2EAC3B84-3D77-4EA0-B8BB-8FB2B46C0D6D

Holotype: MZUSP 116620 (field number MTR 40320; Figs 7, 8A, 9A), an adult male from ‘Bacia do Gelo’, in the highlands of the Serra da Neblina, Parque Nacional do Pico da Neblina, Santa Isabel do Rio Negro, Amazonas State, Brazil (0°47’37”N, 66°01’25”W; 2.013 m a.s.l; datum WGS 84); collected on 18 November 2017 by M. T. Rodrigues, A. Camacho, F. Dal Vechio, I. Prates, J. M. Ghellere, R. Recoder and S. Marques-Souza.

Paratopotypes: Seven individuals, two adult males, MZUSP 116622 View Materials , 116626 View Materials (field number MTR 40302 , 40314 ), two adult females, MZUSP 116621 View Materials , 116623 View Materials (field numbers MTR 40269 , 40304 ) and three subadult females, MZUSP 116624 View Materials , 116625 View Materials , 116627 View Materials (field numbers MTR 40308 , 40310 , 40373 ), from the same locality as the holotype, collected between 18 November and 22 November 2017, by the same collectors as the holotype .

Paratypes: AMNH R-178714 (field number RGZ 12174), an adult male from Camp II, 3.5 km north-east of Pico Phelps (= Pico Neblina ), Cerro de la Neblina, Departamento Río Negro, Territorio Federal Amazonas, Venezuela (00°50’00” N, 65°58’48” W; 2100 m a.s.l.), collected by Richard G. Zweifel on 25 February 1984; USNM 284488 ( RWM 17682), an adult female, Camp II, 3.5 km north-east of Pico Phelps, Cerro de la Neblina, Departamento Río Negro, Territorio Federal Amazonas, Venezuela (00°50’12”N, 65°58’48” W; 2.085 m a.s.l), collected by Alfred L. Gardner on 31 January 1985; MZUSP 116629, 116628, two subadult females

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Etymology: The specific epithet, grandis , is a Latin adjective, meaning ‘big’ or ‘large’, in reference to the larger body size of this new species compared to congeners.

Diagnosis: Following the generic diagnosis of Uzzell (1973), and comments by D. M. Harris and R. W. McDiarmid in Myers & Donnelly (2001), the new species is attributed to the genus Riolama by possessing well-developed limbs with five digits; digits laterally compressed with swollen tips, claws on all digits except for the first finger; tail slightly compressed laterally in section; head scales smooth, without striations; single frontonasal and frontal, paired prefrontals and frontoparietals; dorsal scales hexagonal to rectangular, imbricate, keeled; collar fold distinct; tympanum heavily pigmented and weakly depressed; oblique plicae rather than papillae on the posterior surfaces of the tongue. Additionally, the generic allocation is corroborated by molecular data.

Riolama grandis is distinguished from the remaining species of Riolama by the following combination of traits: (1) large size for the genus (maximum SVL 87.8 mm); (2) head long, HL 0.25 (± 0.01) times SVL; (3) dorsal scales at midbody rectangular, slightly rounded on posterior borders, slightly imbricate, weakly keeled, length 2.5–3.0 times width; (4) 30–34 transverse rows of dorsal scales; (5) 37–42 total scales around midbody: (6) eight to ten longitudinal rows of ventral scales; (7) 19–23 transverse rows of ventral scales; (8) 30 or more temporal scales; (9) seven to nine supralabials on each side; (10) six infralabials on each side; (11) four to six scales in the occipital row; (12) six to eight scales in the postoccipital row; (13) 12–15 femoral pores on each side; (14) long limbs, HLL 0.50 (± 0.03) times SVL, when limbs appressed to trunk, tip of fourth finger overlaps hindfoot to middle of lower leg; (15) 16–21 subdigital lamellae under fourth finger; (16) 23–30 subdigital lamellae under fourth toe; (17) tongue covered by scale-like papillae on the anterior half and by chevron-like plicae on the posterior half; (18) head and body dark brown (in alcohol), generally lacking cream spots dorsally and ventrally; (19) chin grey with irregular dark blotches and two long cream marks laterally; and (20) hemipenis with laterals representing a series of roughly equidistant and remarkably developed flounces, each bearing a single spine; presence of a distinctly enlarged hook-shaped spine at the centre of the hemipenial flounces row.

Description of the holotype ( Figs 7, 8A): An adult male, with 87.8 mm SVL; body cylindrical, moderately stout, wider than deep; TRL corresponds to 46% of SVL. Head large, 1.56 times longer than wide, relatively distinct from neck; HL corresponds to 25% of SVL. Snout moderately broad, sides straight in dorsal view, ESD 0.39 times HL. Limbs well developed, pentadactyl with all digits clawed except for finger I. Forelimbs moderate, 29% of SVL. Hindlimbs moderately long, 46% of SVL. Tail long, two times SVL (posterior fifth regenerated), moderately robust, slightly compressed.

Head scales smooth with a few scattered sensorial pits. Rostral wider than high, visible from above; in broad contact with frontonasal (internasal), nasals and first supralabials. Frontonasal single, large, pentagonal, wider than long; in broad contact with nasals (separating nasals on midline) and prefrontals. Two large prefrontals, slightly longer than wide, shorter than frontal; in contact by a median suture about two thirds of length at margins; in contact with frontal, first supraocular and loreal. Frontal hexagonal, longer than wide, wider anteriorly; in contact with first, second and third supraoculars by a rounded suture; slightly shorter and wider than interparietal. Two large frontoparietals, pentagonal, similar in size to prefrontals, in median contact with each other by a large suture; in wide contact with frontal, third and fourth supraoculars, parietals and interparietal. Interparietal large, hexagonal, 1.6 times longer than wide, with straight margins with parietals, posterior end with a pointed border, trespassing the margins of parietals. Two large parietals, wider anteriorly; subequal to interparietal. A row of enlarged occipitals followed by a row of quadrangular postoccipitals; occipitals with five irregular scales, the median smallest and separated from interparietal by a contact between adjacent occipitals, the laterals largest, pentagonal; postoccipitals quadrangular, much larger than dorsals, the median pair largest, the laterals subsequently being smaller. Four supraoculars, first smallest, second largest, third and fourth subequal.

Nasal single, large, broadly triangular, rounder anteriorly, nostril large, ovoid, just anterior and ventral of centre of nasal, nasal without grooves; in contact with rostral, frontonasal, loreal, frenocular and a postnasal; wide contact with first supralabial, short contact with second supralabial; postnasal triangular, short, between nasal and frenocular, loreal and supralabials. Loreal quadrangular, about as high as wide, separating frenocular from nasal, in contact with prefrontal, first supraocular, first superciliary and postnasal. Frenocular pentagonal, almost as high as long, highest medially, subequal to loreal. Six subocular scales between frenocular and postocular, the fourth largest. Six superciliaries, first largest, larger than loreal, longer than high, second longer than deep, third and fourth smallest, quadrangular; the fifth quadrangular, the sixth higher than long. One row of small scales between second to fourth supraoculars and second through fifth superciliaries. One small preocular between frenocular and first superciliar. Eyelids bordered by two irregular rows of pentagonal scales and two outer rows of small granules; lower eyelid with palpebral disc covered by large opaque pentagonal scales. Temporal scales numerous (36 on the right side) smooth, hexagonal to rounded, subimbricate; increasing in size posteriorly and dorsally. Ear opening broad, ovoid, aligned vertically, partially covered by small scales. Tympanum recessed, heavily pigmented. Eight supralabials, fifth under the eye, first, fourth and seventh largest, twice longer than wide, sixth highest.

Symphyseal scale wider than long, followed by a larger and undivided pentagonal postsymphyseal contacting the first two infralabials. Six infralabials on each side, third longest. Five pairs of mentals; first three pairs contacting the infralabials laterally; first and second contacting each other medially in a straight suture; first pair smaller, almost quadrangular, second pair largest and quadrangular, third pair much wider than long, almost pentagonal; third pair separated from infralabials by a row of elongated scales, the posterior two pairs separated from the infralabials by a series of large, irregular lateral scales, and separated from each other anteriorly by two large irregular scales and posteriorly by a series of small ovoid scales projected anteriorly. A distinct ventral groove between ear openings, slightly arched anteriorly, composed of an irregular row of granular scales. Collar distinct, anterior to pectoral scales, with seven scales in a single row; the median one pentagonal and largest, the remaining ones quadrangular and decreasing in size laterally. Collar fold distinct, filled with rounded, widely spaced, granular scales in six irregular rows; posterior border of medial collar scales partially overlapping anterior pectoral scale row. Gulars arranged in nine irregular transverse rows (including collar); rounded, wider than long, smaller anteriorly, increasing in size posteriorly; the five posterior rows of gulars with central scales widened, quadrangular, much larger than laterals. Sides of neck with small, subequal, subimbricate, pebblelike scales.

Dorsal scales arranged in transverse rows; first six rows with quadrangular or hexagonal scales, smooth; remaining dorsal scales on body and near tail more elongate, rectangular, imbricate, with slightly rounded posterior borders, keeled; keel on dorsal scales straight, not strongly marked; 34 transverse rows of dorsal scales between postoccipitals and posterior insertion of hind limbs; a total of 40 longitudinal rows of midbody scales (including 16 dorsal rows, six to eight lateral rows and ventrals); dorsal caudal scales similar to those on body, progressively loosing keels laterally. Transverse rows of dorsal body scales divided into two or three rows of nearly rounded lateral scales at midtrunk; anterior and posterior third of the area between limbs covered by small scales irregularly arranged; weak keels on more dorsally located lateral trunk scales; scales granular near insertion of forelimb.

Pectoral scales in two rows of seven/four scales laterally, one row of three scales medially; middle scale of three medial ones smaller than lateral ones. Ventral scales quadrangular, in 21 transverse rows and ten longitudinal rows at midbody; six scales in pre-anal shield in two rows, middle scale of anterior row large and quadrangular, lateral scales ovoid and reduced, middle scale of posterior row smaller than lateral scales which are subequal to middle scale of anterior row.

Arm covered dorsally and posteriorly with large, smooth scales; ventral surface of upper arm and inner surface of forearm with granular scales; flattened scales on surface of hand; five depressed fingers, four with claws, thumb clawless; tip of each finger slightly compressed; three scales on dorsal surface of thumb, six on second digit, eight on third, nine/ten on fourth and six/seven on fifth; dorsal scale of penultimate phalanx enlarged on all digits; five ventral scales, including one tubercle, on first digit, eleven on second, sixteen on third, 18/19 on fourth and 11 on fifth; two thenar tubercles in row with thumb tubercle along edge of hand; surface of palm covered with granular scales, some with central depressions; single, rounded, relatively protuberant outer tubercle at base of palm; fourth finger longest, followed in decreasing order by third, second, fifth and first.

Upper leg covered by large, flat scales on anterior surface; more dorsally situated scales granular, weakly keeled scales on dorsal and posterior surfaces of thigh; granular scales, some weakly keeled, on anterior and posterior surfaces of lower leg; ventral surface covered with large, flat scales. Femoral pores 14/14, some scales with one to four grooves extending to scale margins, especially on distal ones. Foot with large, flat scales dorsally; five digits, all clawed; first toe with three dorsal scales, second with seven, third with 11, fourth with 15/16, and fifth with ten, few divided; first toe with eight subdigital lamellae, second with 13/14, third has 19/20, fourth has 26/27 and fifth has 18/17, some partially or completely divided; small, granular scales on sole, some with central depressions.

Dorsal surface of tongue covered with many small scales on anterior half and chevron-shaped plicae on posterior half. Four infralingual plicae, slightly swollen, forming acute angle on midline, decreasing in size posteriorly. Maxilla and premaxilla with 24 bicuspid teeth on each side; teeth slightly curved, anterior cusps lower than posterior ones. Each dentary with 21 bicuspid teeth.

Colour of holotype: In alcohol, dorsum brown with a pair of faded light dorsolateral stripes, two to three dorsal scales wide, beginning on parietals and extending to base of tail, poorly defined on tail ( Fig. 8A); a dark stripe, marginal to dorsolateral stripes; vertebral area between stripes mixed brown and dark brown; head dark brown with irregularly defined darker spots; temporal region and posterior supralabials brown mixed with dark grey; mental and inner sides of mandibular, gular and pectoral region whitish, spotted with bluish grey; outer edges of mandibles, gular and pectoral region, and ventral surfaces of body, limbs and tail bluish grey with scattered dark blotches ( Fig. 8A); flanks greyish brown, each scale primarily dark; area around femoral pores and vent, beneath upper arms, and on ventral surfaces of hands and feet cream with dark mottles.

In life ( Fig. 9A), background colour copper brown, dorsolateral stripes conspicuous; dorsolateral lines ochre anteriorly and brown posteriorly, black vertebral spots; head dark brown, chin and gular area cream with two transverse whitish stripes, chest and venter cream olive with black spots irregularly arranged; lateral scales black with yellowish tips; pre-anal region yellowish with black spots, black spots on legs; iris olive-cream. Lateral colour pattern extends dorsally and is visible from above. In preservative, background colour dark brown, dorsolateral stripes less conspicuous, lateral colour darker than dorsal, with yellowish dots. Ventral colour bluish grey.

Measurements of the holotype (in mm): SVL 87.8; TRL 40.8; HH 10.4; HW 14.1; HL 22.0; ESD 8.6; FEM 14.2; TIB 13.0; FTL 19.4; HUM 9.2; HAL 19.8; TAL 179.0.

Variation: The paratypes present variation in all scale counts except number of infralabials ( Table 4). Temporals vary between 30 and 40; occipitals four to five (one individual with 7) and postoccipitals six to eight. Body size does not differ significantly between sexes (ANOVA, F = 3.73, P = 0.10). Males have proportionally larger FEM (ANCOVA, F = 8.33, P <0.05) and HUM (ANCOVA, F = 8.55, P <0.05), but the remaining morphometric variables do not differ significantly between sexes. Maxillary and premaxillary teeth vary between 20 and 25 on each dentary (N = 6). Colour in life is ontogenetically variable ( Fig. 9B, C), with smaller individuals having a well-marked whitish bar above the eye that fades in larger specimens. Dorsal colour is lighter in smaller individuals, strongly contrasting with the lateral colour pattern. Most paratypes (N = 6) have well-marked black stripes medially to the dorsolateral stripes. In preservative, gular and ventral surfaces are whitish in smaller individuals but greyish in larger individuals, with light coloration restricted to white gular mottles in the larger specimens (N = 7). Testes of the male paratype (AMNH R-178714) are white and measure 4 mm in their largest dimension.