Riolama stellata, 2020

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

( FIGS 8B, 10, 11)

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

LSID: urn:lsid:zoobank.org:act:F3552C7E-55A2-4A11-BC60-8977D050CB02

Holotype: MZUSP 116616 View Materials (field number MTR 40262 ; Figs 8B, 10), a male from ‘ Bacia do Gelo’ , in the

* MTR 40313, a juvenile (24.4 mm SVL), represent an extreme outlier in body-size and was not included in morphometric statistics.

Paratopotypes: MZUSP 116617 View Materials (field number MTR 40309 ) an adult male ; MZUSP 116618 View Materials ( MTR 40312 ) an adult female, and MZUSP 116619 View Materials ( MTR 40313 ), a juvenile male, all from the same locality as the holotype (0°47’34”– 0°47’37”N; 66°01’25”– 66°01’33”W) collected between 18 November and 20 November 2017, by the same collectors as the holotype GoogleMaps .

Paratypes: Five individuals from 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; 2085 m a.s.l), USNM 284491 About USNM (field number RWM 17671 ), USNM 284489 About USNM ( RWM 17680 ), collected by Alfred L. Gardner on 31 January 1985 GoogleMaps ; USNM 562652 About USNM ( RWM 17651 ), on 29 January 1985 , and USNM 562653 About USNM ( RWM 17659 ), USNM 284490 About USNM ( RWM 17660 ), on 30 January 1985 , collected by Roy W. McDiarmid; USNM 284492 About USNM ( RWM 17284 ), from Camp II, 2.8 km north-east of Pico Phelps , Cerro de la Neblina, Departamento Río Negro, Territorio Federal Amazonas, Venezuela (00°50’00”N, 65°58’48”W; 2085–2100 m a.s.l), collected by Roy W. McDiarmid on 21 February 1984 GoogleMaps ; USNM 562654 About USNM ( ALG 14138 ), from Camp II, 2.5 km north-east of Pico Phelps , Cerro de la Neblina, Departamento Río Negro, Territorio Federal Amazonas, Venezuela (00°50’04”N, 65°58’48”W; 2085 m a.s.l), collected by Alfred L. Gardner on 20 March 1984 GoogleMaps .

Etymology: The specific epithet is the Latin adjective stellatus, which means ‘starred’, referring to the ventral and lateral colour pattern composed of light dots scattered on a dark background, which resemble a starry night sky.

highlands of the Serra da Neblina, Parque Nacional do Pico da Neblina, Santa Isabel do Rio Negro, Amazonas State, Brazil (0°47’34”N, 66°01’30”W; 2000 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.

Diagnosis: The generic diagnosis of R. stellata follows that presented for R. grandis above. Riolama stellata is distinguished from the remaining species of Riolama by the following combination of traits: (1) a small body size for the genus (maximum SVL 52.9 mm); (2) head short, HL 0.19 (± 0.01) times SVL; (3) dorsal scales at midbody slightly hexagonal, imbricate, broadly keeled, length 2.5–2.9 times width, dorsal rows clearly defined; (4) 33–38 transverse rows of dorsal scales; (5) 34–38 total scales around midbody; (6) six longitudinal rows of ventral scales; (7) 17–22 transverse rows of ventral scales; (8) 14–23 temporal scales; (9) six to seven supralabials on each side; (10) six to seven infralabials on each side; (11) five to seven scales in the occipital row; (12) five to seven scales in the postoccipital row; (13) eight to 11 femoral pores on each side; (14) short limbs, HLL 0.37 (± 0.02) times SVL, when limbs appressed to trunk, tip of fourth finger overlaps hindfoot to middle of third toe; (15) subdigital lamellae under fourth finger: 11–13; (16) subdigital lamellae under fourth toe: 14–19; (17) tongue surface entirely covered with plicae arranged in chevrons with anteromedial apices; (18) head and body dark (in alcohol), head dorsally and ventrally spotted with cream dots, body unspotted dorsally, ventrally black and heavily spotted with cream dots; (19) chin dark, blotched with cream marks; and (20) hemipenis with laterals consisting of a series of roughly equidistant and moderately developed flounces, each bearing a single spine; absence of the distinctly enlarged hook-shaped spine at the centre of the hemipenial flounces row.

Description of the holotype ( Figs 8B, 10): An adult male, with 47.2 mm in SVL; body cylindrical, elongate, wider than deep. TRL corresponds to 53% of SVL. Limbs short but well developed, limbs pentadactyl with all digits clawed except for finger I. Forelimb 24% of SVL and hindlimb 37% of SVL. Tail slightly flattened laterally in section, about 1.9 times the SVL. Head short, 1.2 times longer than wide, HL 0.19 times SVL, only slightly differentiated from neck; snout short, ESD 0.37 times HL.

Head scales smooth with scattered sensorial pits, more numerous on anterior region. Rostral wider than high, visible from above; broad contact with frontonasal. Frontonasal large, single, pentagonal, longer than wide, slightly wider posteriorly, wider and shorter than frontal, completely separating nasals. Two prefrontals, quadrangular, widest anterolaterally; in contact with each other by a median suture about half size of length at margins; in contact with frontonasal, frontal, first supraocular, thigh contact with first superciliary and loreal. Frontal hexagonal, large, slightly longer than wide, contacting first three supraoculars laterally. Two large frontoparietals, pentagonal, about 50% larger than prefrontals, contacting each other by a large suture; in wide contact with frontal, third and fourth supraoculars, parietals and interparietal. Interparietal large, pentagonal, longer than wide, with straight margins with parietals, posterior end with a straight border, coincident with margins of parietals. Two large parietals, much wider anteriorly; slightly longer than interparietal. A row of five occipitals followed by a row of six postoccipitals; middle occipital scale smaller than lateral ones, medial pair of postoccipitals larger than outers. Four supraoculars, first smallest, second largest, fourth smaller than third.

Nasal single, large, triangular, rounder anteriorly, nostril ovoid, near middle of nasal scale, nasal not grooved; in contact with rostral, frontonasal, loreal and frenocular, in wide contact with first supralabial, and short contact with second supralabial. Loreal quadrangular, two times higher than wide, in contact with frontonasal, prefrontal, first superciliary, preocular and frenocular, not contacting supralabials. Frenocular pentagonal, almost as high as long, shorter than loreal. Four subocular scales between frenocular and postocular, the third largest and extending ventrally between fourth and fifth supralabials. Seven superciliaries between loreal and posterior edge of eye, separating upper eyelid from supraoculars, first two largest. A single, small scale situated between second and third supraoculars and fourth and fifth superciliaries. One small preocular between frenocular and first superciliary. Eyelids bordered by a single row of small granules on upper eyelid and two irregular rows at lower eyelid; lower eyelid with palpebral disc covered by large opaque pentagonal scales. Twenty smooth temporal scales, hexagonal to rounded and subimbricate; increasing in size posteriorly and dorsally. Ear opening broad, ovoid, aligned vertically. Tympanum moderately recessed, heavily pigmented. Six supralabials, fourth under the eye, first and sixth largest, two times longer than wide, fifth highest.

Symphyseal scale wider than long, followed by a larger and undivided pentagonal postsymphyseal contacting the first two infralabials. Six infralabials on each side, first longest. Five pairs of mentals; first three pairs contacting the infralabials laterally, contacting each other medially in a straight suture; first pair smaller and almost quadrangular, second pair largest and quadrangular, third pair much wider than long, almost pentagonal; posterior two pairs separated from infralabials by a series of large, irregular lateral scales, and from each other by two rows of elongate scales projected anteriorly. A distinct groove between ear openings, separating mentals from gulars, composed of an irregular row of granular scales. Collar distinct, anterior to pectoral scales, consisting of a row of seven enlarged rectangular scales between anteromedial insertions of forelimbs; medial scale largest and more quadrangular than others; collar fold distinct, with rounded, widely spaced, granular scales in two irregular rows. Gular scales arranged in eight transverse rows (including collar); anterior four transverse rows of gulars with subequal scales; posterior rows of gulars with paramedian scales presenting two longitudinal rows of greatly enlarged rectangular gulars, larger posteriorly. Lateral scales on neck roughly quadrangular, slightly protuberant; scales between the lateral extension of collar and forelimb small, granular.

Dorsal scales arranged in transverse rows; first six rows with hexagonal scales, as wide as long, imbricate, smooth; remaining dorsal scales on body and near tail more elongate, hexagonal, more than two times longer than wide, more imbricate and keeled posteriorly; keels broad; dorsal scales not forming longitudinal rows; 34 transverse rows of dorsal scales between postoccipitals and posterior insertion of hind limbs; 38 longitudinal rows of midbody scales (including 16 dorsal rows, eight lateral rows each side and ventrals); dorsal caudal scales similar to those on body, progressively loosing keels laterally. Lateral scales progressively smaller than dorsals towards venter; nearly rectangular at mid-trunk, imbricate, divided into two occasionally three rows per dorsal row; granular scales irregularly arranged over about a third of the lateral area between limbs; weak keels on more dorsally located lateral trunk scales; scales granular near insertion of hind limb.

Pectoral scales in two rows, ten scales in anterior row and seven in posterior one. Ventral scales quadrangular, in 18 transverse rows and six longitudinal rows at midbody; six scales in pre-anal shield in two rows, anterior middle scale largest, pentagonal, bordered laterally by anterior and posterior pair of about equal size and posteromedially by a small quadrangular scale.

Forelimb covered dorsally and posteriorly with large, smooth scales on anterior and posterior surfaces of upper arm and forearm; ventral surface of upper arm covered with granular scales; hands covered dorsally with flattened, quadrangular plates; five short fingers, thumb reduced and clawless, four other digits clawed, depressed, with compressed tip; two scales on dorsal surface of thumb, five on second digit, six on third, seven on fourth and five on fifth; thumb with three subdigital lamellae, basal one in form of keeled tubercle, other two flattened; second digit with eight ventral scales, third with nine/ten, fourth with 12 and fifth with seven, most undivided, all flattened; two additional tubercles in row with basal thumb tubercle along border of palm; palm covered by granular scales, some with central depressions; slightly rounded, protuberant tubercle located on posterolateral border of palm; fourth digit longest, followed in decreasing order by third, second, fifth and first.

Hindlimbs covered on anterior and dorsal surfaces of thighs with large scales, generally smooth, few slightly keeled; scales on posterior surface of thigh small, granular; scales on ventral surface rounded; scales on ventral surface of lower leg large, smooth, those on dorsal surface smaller, some weakly keeled, becoming granular near foot. Femoral pores nine/nine, with one to three grooves extending to scale margins. Feet covered dorsally by large flattened scales; five short digits, all clawed; scales on dorsal surface of toes smooth, numbering three on first toe, five on second, eight on third, ten on fourth and six on fifth; five subdigital lamellae on first toe, seven on second, 12 on third, 14 on fourth and nine on fifth, some scales partially or completely divided; four semicircular tubercles on inner edge of basal lamellae on third toe; scales on sole of foot small, granular, often with central depression.

Tongue surface entirely covered with plicae arranged in chevrons with anteromedial apices; some plicae divided, especially posteriorly, into fragments of variable length. First infralingual plicae distinct, long and pointed; other three rounded and meeting in acute angle on midline. Eighteen teeth on each side of upper jaw; anterior ones curved and primarily unicuspid, posterior ones more erect and bicuspid; posterior cusp much higher than anterior one. Mandible with seventeen teeth on each side; morphology similar to maxillary teeth.

Colour of holotype: Background coloration in life is dark brown on dorsum and black on ventral, lateral, gular and mental regions ( Fig. 11). Dull orange-brown dorsolateral stripes extending to the tail, dorsally bordered by faded black parallel stripes. Black surfaces with several small whitish blotches. Limbs black with small whitish blotches on dorsal and ventral surfaces. Tail dark brown. Colour in preservative ( Fig. 8B) is similar, face and dorsal surface of head dark brown with many small, rounded, cream spots, somewhat poorly defined; lower mandible and gular region grey, slightly bluish, with small, irregular whitish spots; dorsum dark brown with irregular light brown dashes, no rounded dots; longitudinal, dorsolateral cream stripe, 0.5 to 2.5 scales wide extending from occipital scales on head to posterior part of tail, less distinct on tail; dorsally tail dark brown with light brown dashes; sides blackish brown with many small, rounded, cream or whitish dots on all transverse scale rows; ventral surfaces of body, forelimbs, hindlimbs and tail leadgrey and marked with many, small rounded whitish spots; venter slightly yellowish anteriorly; one to four spots on each ventral scale, ventral spots larger than lateral ones; pattern on pre-anal shield similar; spots on ventral surface of tail more scattered and considerably smaller than those on other parts of venter; fore- and hindlimbs, including toes, blackish brown with white or cream dots similar to sides; palms and soles greyish, without spots.

Measurements of the holotype (in mm): SVL 47.2; TRL 24.9; HH 5.0; HW 7.3; HL 9.1; ESD 3.4; FEM 6.2; TIB 5.7; FTL 8.2; HUM 4.4; HAL 8.8; TAL 90.4.

Variation: The type series shows some variation in quantitative morphological traits, as presented in Table 4. Temporals vary between 14 and 23; occipitals five to seven; postoccipitals five to seven (Supporting Information, Table S2). Sexes do not differ significantly in size ( ANOVA, F = 0.38, P = 0.55), but males are proportionally larger in HW than females ( ANCOVA, F = 19.80, P> 0.01).

Additionally, the following morphological traits show some variation among the paratypes when compared to the holotype: right prefrontal smaller than left (N = 1); posterior fifth of right frontal separated into second scale (N = 1); frontal and left frontoparietal fused, replaced by anomalous crenulate scale sutures (N = 2); a weakly defined depression (similar to nasal groove) from nostril to supralabial scale (N = 4); four or six subocular scales (N = 5); six superciliaries (N = 4); seven or eight scales on lower border of upper eyelid (N = 9); six or seven scales on upper border of lower eyelid (N = 6); four to six scales in middle of palpebral disc (N = 6); seven supralabials on left side (N = 2); seven infralabials (N = 1); three pairs of chin shields, sometimes three pairs and one shield on only one side (N = 5); seven, eight or ten scales in collar (N = 7); 12 or 13 scales in anterior pectoral scale row (N = 9); pre-anal shield of seven to ten scales (N = 12); tongue plicae divided or not, or with large number of scales, especially on middle part (N = 11); 18 (N = 2) to 19 (N = 1) teeth on each side of upper jaw; mandible with 17 (N = 2) to 18 (N = 1) teeth on each side.

In life, paratypes are dorsally dark brown, but dorsolateral stripes fade to pale brown in some adult males, and in all females and juveniles. Dark brown marks occur between dorsolateral lines in larger individuals. Light longitudinal body stripes may begin on first or fourth supraocular scales or on parietal scales; straight blackish longitudinal lines bordering light dorsolateral stripes sometimes ending middorsally or extending to tail. Lateral colour deep black with white spots in adult males; dark brown with small brown spots the same colour as dorsolateral lines in adult females and juveniles. A small juvenile ( MTR 40313) has a lateral dark brown colour with light brown blotches arranged in longitudinal lines. In preservative, venter and gular regions deep black in males with well-marked white spots; in females, venter and gular regions are dark brown, with small light brown spots, light brown midventral colour and cream gular region. Ventral and gular regions in juveniles entirely cream without spots.