Scinax insperatus, Silva, Helio Ricardo Da & Alves-Silva, Ricardo, 2011

Silva, Helio Ricardo Da & Alves-Silva, Ricardo, 2011, A new bromeligenous species of the Scinax perpusillus group from the hills of the State of Rio de Janeiro, Brazil (Anura, Hylidae), Zootaxa 3043, pp. 54-68 : 55-65

Scinax insperatus sp. nov.

( Figs 1–5 )

Holotype. MNRJ 72813. Adult male, obtained from Alcantarea imperialis (Bromeliaceae) in the district of Vera Cruz (22º 13’ 14.6” S and 43º 26’ 02.1” W, near 680 m), Municipality of Miguel Pereira, State of Rio de Janeiro, Brazil, on 11 October 2010 by H. R. Silva, R. Alves-Silva, and G. C. Gonçalves.

Paratypes. Collected with the Holotype: MNRJ 72814–72818 adult males, and MNRJ 72819, 72820 adult female.

Referred specimens. Scinax insperatus sp. nov.: Brazil: Rio de Janeiro: Municipality of Miguel Pereira, Distrito de Vera Cruz: RU 7306–7311, 7313, 7315–7322, 7324, 7326–7330, 7332–7335, 7337–7343, Municipality of Valença, Serra da Concórdia: MNRJ 40426, RU 7497–7499. Tadpoles: Scinax insperatus sp. nov. Brazil: Rio de Janeiro, Municipality of Miguel Pereira, Distrito de Vera Cruz: RU 7279.

Diagnosis. The new species is placed in the genus Scinax based on observation of the origin of the m. pectoralis abdominalis through a well-defined tendon on the pelvis ( Faivovich 2002); and assigned to the S. perpusillus group by the absence of webbing between Toes II and III of adult specimens, and by direct observation of its reproductive behavior, that takes place in bromeliads, with egg clutches partitioned, with single eggs laid one at a time ( Alves-Silva & Silva 2009), and tadpoles developing in water accumulated between the leaves of bromeliads.

The following combination of characters distinguishes Scinax insperatus sp. nov. from other species of the Scinax perpusillus species group (sensu Faivovich, 2002): (1) larger size (SVL ≥ 18.6 mm males; 23.0 mm females); (2) snout with a distinct rostral keel; (3) head slightly longer than wide; (4) tympanum round, half the size of the eye, covered by small metallic beige and black little spots; (5) canthus rostralis hardly evident; (6) loreal region slightly concave, skin with pronounced tubercles; (7) gular region with discrete pigmentation, dark chromatophores randomly dispersed; (8) eyes protruding and prominent; (9) tubercles present throughout the dorsum, granulation moderate; (10) absence of colored spots in the hidden areas of limbs, inguinal, and axillary regions; (11) ventrally, the contour of the body and limbs ornate by metallic beige granules regularly spaced; (12) thigh and tibia length greater than SVL; (13) arms and fingers with well defined dark stripes; (14) palmar surface with moderate pigmentation; (15) palmar tubercle bifid; (16) webbing lacking between Toes I and II, and vestigial or absent between Toes II and III; (17) plantar surface densely pigmented; (18) tadpole body brown with whitish opaque fins, after Stage 27 black irregular spots appear on ventral fin, and after Stage 34, metallic yellow blotches appear on ventral fin surrounded by black lining.

Comparison with other species. Scinax insperatus sp. nov. differs from all species in the Scinax perpusillus group by possessing a unique combination of color pattern. While all other species know to the group (except S. belloni ) have bright yellow spots on the inguinal region and hidden surfaces of limbs, S. insperatus sp. nov. has the general background body colors on these areas. However, it can be promptly distinguished from S. belloni by having dark, metallic-beige colored tubercles on the dorsal surfaces ( S. belloni lacks any markings on dorsum, hind limbs, and hidden surfaces). The new species also lacks inguinal glands, which are evident in S. belloni . Furthermore, male individuals of S. insperatus sp. nov. are larger (18.5 – 21.9 mm) than those of S. faivovichi (16.2 – 18.0 mm; Brasileiro et al. 2007b), S. melloi (16.8 – 17.9 mm), S. perpusillus (17.0 – 20.3 mm), and S. tupinamba (16.3 – 19.3 mm); being smaller than S. alcatraz (19.7 – 24.4 mm; Brasileiro et al. 2007a), S. belloni (19.8 – 23.0 mm; Faivovich et al., 2010), and S. v -signatus (21.5 – 23.9 mm). By presenting a moderate rostral keel S. insperatus sp. nov. differs from S. alcatraz , S. peixotoi , S. tupinamba , and S. v -signatus, which have well developed keel. S. belloni is the only known species with palmar tubercle not bifid, which is bifid in all other species, including S. insperatus sp. nov. S. peixotoi is the only known species of the group with webbing between Toes I and II ( Brasileiro et al. 2007a), in all other species, including S. insperatus sp. nov., this webbing is lacking. In addition, the tadpoles of the new species are the first registered for the group that develops metallic yellow blotches on the ventral fin after Stage 34.

Description of holotype. Body of moderate size; head barely longer than wide, slightly protruding in lateral view and mucronate in dorsal view, rostral keel evident; canthus rostralis curved; loreal region concave, with six scattered pronounced tubercles; tympanum round, diameter approximately equal to half that of the eye, its surface whitish with evenly distributed melanophores over most of its surface, except the margins where they are more grouped, and ventrally forming a thicker stripe, small dots of metallic beige are also scattered across the tympanic surface and concentrated on the superior margin; supra tympanic fold defined, with tubercles from the corner of the eye to the insertion the arm. Vocal sac subgular, externally evident by the loose skin on the sides of the jaw, and immediately above the pectoral region. Tongue oval, free laterally and posteriorly, shallowly notched. Vomerine teeth in two barely convex series posterior to choanae, each bearing four (right) and two (left) teeth. Choanae elliptical, lateral, situated proximal to the maxillae. Vocal slits present, longitudinal, originating on the side of the tongue, extending posteriorly towards the corner of the mouth. Pectoral fold absent. Cloacal opening horizontal, situated at upper level of thighs. Skin on throat smooth, granular on the belly and undersurfaces of thigh. Dorsum of head and body with scattered rounded low granules; similar tubercles are also scattered at much lower densities on the dorsum of limbs. Forearm slightly more robust than upper arm. Axillary membrane absent. Fingers slender; subarticular tubercles single, conical on Fingers II and III; rounded on Fingers IV and V. Palmar tubercle somewhat flat, medially bifid; thenar tubercle elliptical. Discs elliptical, wider than long; disc on Finger II slightly smaller than the others, nearly rounded. Webbing absent between Fingers II and III; basal between Fingers III and IV, and absent between Fingers IV and V. Slender whitish nuptial glands covering the base of thumb dorsomedially, extending medially up to the outer margin of the palmar tubercle, and distally up the base of the first phalanx. Finger lengths 2<5≤3<4 ( Fig. 2 D). Hind limbs slender; tibia longer than thigh, entire hind limb longer than SVL. Several rounded, low tubercles present on the heel, and contiguous with a series of irregular, slightly larger tubercles that extend through the margin and lower part of the tarsus up to the lateral margin of foot. Toes slender; subarticular tubercles conical. Outer metatarsal tubercle rounded, small; inner metatarsal tubercle subcircular, more than twice as large as the outer tubercle. Rounded, low supernumerary tubercles present along the metatarsi. Discs subelliptical, wider than long. Toe lengths 1<2≤3~5<4 ( Fig. 2 F); foot webbing formula I—II—III2—3+ IV 3 +— 2V. Tarsal fold absent.

Color of the holotype in preservative. Overall grayish green-brown with light to dark brown stripes and whitish to cream dots scattered on dorsum. Venter whitish cream with scattered dark brown small dots. Surface of the hand and foot with the same pattern of small dark dots of the venter, plus brown irregular areas on the margins ( Fig. 1 ).

Color in life. Color pattern was described based on observation of live specimens before they were euthanized and fixed, all the type series and referred specimens from RU collection were used in constructing this description. The dorsum is light olive beige to hazel, speckled with metallic yellow spots; this background is crossed by five dark brown stripes ( Fig. 2 ). On the head dorsally there is an interorbital stripe anteriorly and posteriorly delineated by light beige margins; on the canthus rostralis, there is a dark brown, slender stripe from the eye to the tip of the snout. The area underneath the eye has three small dark spots. The anterior third of the dorsum is crossed by two straight dark brown stripes that run from the eye towards the vertebral region at about a 45º angle; in the posterior region a V-shaped stripe, similarly colored, run diagonally from the midline of the body towards the inguinal region; when the animal is in a resting position, this stripe is continuous with stripes that cross the thigh, calf, and foot ( Fig. 1–2 ). On the lateral region of the body a stripe extends from the posterior portion of the eye (confluent with a similar line over the pupil), passes around the tympanum, and extends to the inguinal region. It becomes a bit thicker around the abdominal part of the trunk and thinner before reaching the inguinal region. The axillary region is whitish and translucent. The dorsal portion of the arms (considering the animal at resting position) is crossed by five large dark stripes, one on the wrist, two on the forearm, one at the elbow, and one at the upper arm, the last two less defined ( Fig. 1–2 ). Fingers II, III, IV, and V have a dark stripe on the joint of the finger pads. Finger IV has two additional stripes, and Fingers III and V have one additional stripe. On the hindlimb, the thigh is crossed by four dark stripes (two not so well defined), one on the knee, three on the calf, one on the heel, and one on the foot. All toes have a stripe on the joint of the finger pad. Toes I, II, III, and V have an additional stripe, and Toe IV have two additional stripes. The stripes on the thighs run towards the ridden areas of the leg; the stripes on the hidden part of the thighs anastomose and form horizontal bar. The cloacal region has an irregular shaped dark spot made up of an agglomerate of melanophores. Most of the venter is pale whitish and somewhat translucent (the internal organs can bee seen through the skin), groups of concentrated melanophores form scattered small dark spots, a similar pattern of dark areas is observed on the ventral surface of legs, arms, hands, and feet. On the margin of the body a line of metallic beige spots (coloring the tubercles) forms roughly the outline of the animal ( Fig. 3 ). In preservative the darker pattern is preserved, however the color of the body becomes greener brown and the metallic coloring vanishes. The hidden parts become whitish opaque.

Variation. Variation of measurements taken of adult males and females are given in Tables 1 and 2. Males are smaller than females ( Fig. 2 A), but their color pattern are similar, although the darker stripes appear to be darker on females. In addition, females have more pronounced tubercles over their body. The thickness of the interorbital stripe is variable; the stripe on the canthus rostralis may be interrupted, the anterodorsal stripes may be longer, straight or arched to form the shape of opposing parentheses; these lines may extend posteriorly and fuse with the V-shaped marking; the posterior lines of the V-shaped marking may be interrupted medially. The loreal region varies from concave to slightly flat. The membrane between fingers may be absent, basal between Fingers III and IV, and between Fingers IV and V; a vestigial membrane may be present between Toes II and III. The vomerine teeth may be positioned more anteriorly, approximately along an imaginary line between the choanae. On the gular region some specimens may have darker dots formed by concentration of melanophores. The internal hidden area of the thigh may be darkly pigmented without whitish areas, or present a variable number dark stripes (2 to 4).

Males (n = 35) Females (n = 5)

Range Mean SD Range Mean SD ED 2.2–2.5 2.2 0.1 2.4–2.8 2.7 0.2 END 2.3–2.7 2.5 0.1 2.9–3.0 2.9 0.1 ETD 1.1–1.6 1.4 0.1 1.7–1.8 1.8 0.1 FL 7.0–8.6 7.7 0.4 9.4–9.6 9.4 0.3 HL 7.4–8.7 7.9 0.4 9.2–9.5 9.3 0.3 HW 6.5–7.9 7.2 0.3 8.4–8.9 8.5 0.2 IND 1.6–2.0 1.8 0.1 1.9–2.2 2.0 0.1 IOD 1.9–2.8 2.5 0.2 2.9–3.4 3.0 0.2 SVL 18.5–21.9 20.1 0.8 23.2–24.7 23.8 0.6 TBL 9.6–11.9 10.9 0.5 12.8–13.5 13.1 0.4 TD 1.0–1.3 1.1 0.1 1.3–1.5 1.3 0.1 THL 8.7–10.9 9.8 0.6 10.9–12.5 11.8 0.6 Tadpoles. Measurements for a sample of 22 tadpoles ranging from Stage 25 to 43 are presented on Table 3 (Note that for some stages we have measured more than one individual). Body is oval in dorsal view and wider than deep in lateral view. Snout is rounded in dorsal and lateral profiles. Eyes are dorsolateral. Nostrils are rounded, directed anteriorly, with margins delineated by dark pigmentation, situated closer to the tip of snout than to the anterior edge of the eye. Spiracle sinistral, short, tubular, and with the inner wall attached to the body, opening in a posterolateral orientation, at about the posterior third of the body. The anal tube is longer than wide, dextral, enlarged near the body, attached to the ventral fin. Tail slightly longer than body. Fins with straight edges, dorsal and ventral of equivalent height; dorsal fin originating at the junction of the body and tail; both fins tapering to blunt tip at end of the tail; a few isolated muscle fibers reach the tip of the tail.

Mouth anteroventral; oral disc ventral ( Fig. 4 ), large, not emarginated, bordered by one row of papillae anteriorly, two rows posteriorly, four to six (multiserial) rows of papillae laterally. Odontophores organized in two upper and three lower rows of keratodonts, with the second upper row interrupted medially (labial tooth row formula 2(2)/3); lower rows are of similar length; jaw sheaths strongly developed and serrated, as if made up of amalgamated columns that end in sharply pointed V-shaped tip. Upper and lower jaw sheaths curved, forming a large arch. Lateral lines present, consisting of round unpigmented stitches forming eleven lines: preorbital; infraorbital, oral, angular (visible only laterally), dorsal (represented by a few stitches, and the line stops near the insertion point of the dorsal fin), medial (runs only to half of the tail musculature), and ventral (only laterally); no lines, or stitches, present ventrally.

TABLE 3. Measurements (in mm) of tadpoles of Scinax insperatus sp. n. Stages follows Gosner (1966), total length (LT), body length (BL), body height (BH), body width (BW), tail length (TL), tail height (TH), dorsal fin height (DFH), ventral fin height (VFH), eye diameter (ED), inter-narial distance ( IND), interorbital distance (IOD), eye-snout distance (ESD), eye-nostril distance ( END), oral disc width (ODW) – Repeated stages represent the number of specimens on that stage that was measured. Coloration of live tadpoles. Background color varies from pale (early stages) to darker brown (late, pre-metamorphic stages). Melanophores are scattered through the skin, being more concentrated on the superior and inferior margins of the caudal musculature and on the dorsum and venter of the body and head. The caudal musculature surface may have small dark rings. The ventral fin is translucent in early stages, becomes darker and less transparent after Stage 30, when melanophores become more concentrated. On the ventral fin, a similar pattern of darkening followed by the formation of blotches occurs after Stage 27, becoming more evident after Stage 30. After Stage 40 the darker region of the ventral fin extends and is continuous to the inferior margin of the caudal musculature. The spiracle is brown as the rest of the body and the vent tube is not pigmented, appearing whitish.

Metallic-yellow pigmentation, forming small spots, similar to that covering the body of the adult is observed over the body and caudal skin of the tadpole ( Figs. 4 B; 5 A). This pigmentation is more common and intense over the dorsum of the body and head; being moderate over the venter, where it concentrates around the belly. On the caudal skin, these pigments are present, but scattered; however, the ventral fin becomes more densely pigmented after Stage 37, when blotches or irregular markings become outlined by darker pigmentation. The oral disk is whitish with the papillae outlined by darker contour sprinkled by metallic-yellow pigmentation. The eyes have a dark pupil that is encircled by an orange-pigmented halo with more concentrated pigmentation near the pupil and scattered small dots away from the center.

From Stage 41 until metamorphosis ( Fig. 5 ), the body, legs, and feet (later the arms and hands) have the stripes and color pattern of the adult. On the dorsum of the body and head yellow metallic spots are present and seem to be located in the same places where later, the adults will have tubercles. Recently metamorphosed individuals are even more similar in color to adults. After fixation (less then a month in 5% formalin) the general color patter is maintained, but the colors are somewhat attenuated and washed.

Distribution. Scinax insperatus sp. nov. was collected from two nearby sites in the hills of the Municipality of Miguel Pereira, and a third one in Serra da Concórdia, Municipality of Valença (22º 21’ 30.5” S; 43º 47’ 11.7” W, 845 m), a locality about 40 km northwest of the type locality, in the State of Rio de Janeiro ( Fig. 6 ). We searched the region designated as the type locality, following dirt roads along the Santana River (near the type locality), and found a few isolated granitic outcrops where the bromeliad Alcantarea imperialis was growing (22º 28’48.5” S; 43º 24’ 06.1” W, 570 m, 22º 31’02.3” S; 43º 25’54.9” W, 710 m; and near 22º 30’ 14.7”S; 49º 26’90.1” W, 489 m), but we were unable to verify the presence of the frog.

Advertisement calls. Males interact when calling, forming duets ( Fig. 7 ) in a manner similar to that described for Scinax v-signatus and S. perpusillus by Alves-Silva and Silva (2009). Duets (antiphonic interaction) lasted 27.9 to 49.2 s (n = 8; x =37.1 + 8.1), with dominant frequency varying from 4478.9 to 4665.0 Hz (n=5; x =4567.8 Hz + 89.7). The duets had from 48 to 97 notes (n=7; x =68.4 +17.5), 597 to 934 pulses (n=5, x =580.2 + 229.0). After the emission of the last “closing notes”, both males stop calling between 108 to 148 s (n=11, x = 123.3 s + 13.7 s). During the duets male one (the one that emitted the first opening notes) emitted 25 to 50 notes (n=7, x =35.7 + 9.2) while the second male emitted 23 to 47 notes (n=7, x =32.7 + 8.4). The interval between notes for male one lasted 0.630 to 0.886 ms (n=7, x =0.701 + 0.110), for male two lasted 0.050 to 0.631 ms (n=5, x =0.670 + 0.050). Male one emitted 155 to 434 pulses (n=5, x =299.4 + 115.0) and male two emitted 223 to 500 pulses (n=5, x =280.2 + 130.2).

Reproduction and natural history. In four visits to the type locality, between the months of October and November 2010, we heard and observed males of Scinax insperatus sp. nov. calling from Alcantarea imperialis (Bromeliaceae) . Males were calling in a head down position (facing the water in the interior of the bromeliad), as described for S. perpusillus and S. v-signatus by Alves-Silva and Silva (2009). We also heard males calling from Vriesea gigantea (Bromeliaceae) in one of the localities; there, the bromeliads were growing both on the ground and on trees about 15 meters from the ground. However, we only found tadpoles in the tanks between the leaves of A. imperialis . Eggs and tadpoles were found in several stages of development in the water of the bromeliads. We also filmed an amplectant couple laying eggs, and were able to confirm that egg laying takes place in a manner similar to that described for S. littoreus , S. perpusillus , and S. v-signatus by Alves-Silva and Silva (2009), with the couple in the water, and female holding her arms against the bromeliad’s tank leaves, arching her back, so that the cloaca is pointed up, and laying one egg at a time. We observed eight eggs being laid in a sequence at the same tank. We also visited another locality, about 40 km (straight line) from the type locality, in the Municipality of Valença, in the State of Rio de Janeiro, and found a few adults and tadpoles in the bromeliad Alcantarea regina .

Conservation status. Although there are small farms, housing, and a gas-pipeline fragmenting the areas were we sampled the new species, the fact that they inhabit bromeliads growing on granitic outcrops, that are hard to reach due to the steepness of the terrain, the new species does not seem to be especially threatened by extinction. However, because the range of this species is fragmented (we failed to find suitable new localities between the most distant collecting sites), this species should be further investigated for geographic distribution and possible risks associated with the small range of its populations.

Etymology. The specific epithet (“ insperatus ”) is a Latin adjective meaning unexpected, unlooked for, unanticipated, and is used as an allusion to the serendipitous finding of the new species where our expectation was to find the southernmost limit of Scinax v-signatus .

Figures

FIGURE 1. Scinax insperatus sp. n. Holotype MNRJ 72813. (A) dorsal view, (B) ventral view, (C) lateral view of the head, (D) palmar view of the hand, and (E) plantar view of the foot.

FIGURE 2. Scinax insperatus sp. n. (A) Couple in amplexus (male RU 7333, SVL 20.0 mm; female RU 7343, SVL 23.8 mm) and (B) male (RU 4340, SVL 20.4 mm) illustrating color of live specimens.

FIGURE 3. Ventral view of live male specimen (RU 4340, SVL 20.4 mm) of Scinax insperatus sp. n.

FIGURE 4. Tadpole of Scinax insperatus sp. n. (A) Ventral view Stage 36 (RU 7900), (B) detail of caudal pigmentation showing yellow blotches at Stage 43 (RU 7901), (C) Dorsal view Stage 36 (RU 7900), and (D) detail of mouth at Stage 36 (RU 7900).

FIGURE 5. (A) Tadpole Stage 41 (RU 7901) of Scinax insperatus sp. n. and (B) recent metamorphosed specimen (RU 7911).

FIGURE 6. Map of the state of Rio de Janeiro, Brazil with the location of two collecting sites for Scinax insperatus sp. n. Square type locality (Municipality of Miguel Pereira, 22 º 13 ’ 14.6 ” S and 43 º 26 ’ 02.1 ” W), triangle a second locality (22 º 21 ’ 30.5 ” S; 43 º 47 ’ 11.7 ” W) in the Municipality of Valença (modified from http: // www. agritempo. gov. br / altimetria / RJ. html).

FIGURE 7. Oscillogram of a duet (antiphony) based on records of interacting males (RU 7491 - 92) of Scinax insperatus sp. n. (A) complete call with highlights of the “ opening ” and “ closing ” notes, (B) detail of the “ opening ” notes and sequence of the two calling males, and (C) detail of the “ closing ” notes and sequence of the two males.

Tables

TABLE 1. Measurements (in mm) for the type series of Scinax insperatus sp. n. Snout-vent length (SVL), head length (HL), head width (HW), tympanum diameter (TD), eye diameter (ED), interorbital distance (IOD), eye-nostril distance (END), internostril distance (IND), thigh length (THL), tibia length (TBL), and foot length (FL). (M) Male and (F) female. Boldface indicates the holotype.

Number MNRJ 72813	SVL 19.5	TBL 10.5	THL 10.1	FL 7.7	HW 7.3	HL 7.9	IND 1.8	END 2.3	ED 2.2	IOD 2.5	ETD 1.6	TD 1.2	Sex M
MNRJ 72814	19.3	10.7	10.0	7.6	7.0	7.5	1.7	2.3	2.1	2.4	1.4	1.1	M
MNRJ 72815	20.7	11.6	10.5	8.3	7.6	8.5	1.9	2.7	2.4	2.8	1.3	1.1	M
MNRJ 72816	20.4	10.8	9.9	7.5	7.3	8.2	1.9	2.2	2.2	2.9	1.4	1.1	M
MNRJ 72817	20.5	10.7	10.1	8.0	7.2	8.8	1.8	2.4	2.2	2.5	1.3	1.2	M
MNRJ 72818	18.6	9.7	8.2	6.9	6.8	7.5	1.6	2.3	2.1	2.6	1.3	1.1	M
MNRJ 72819	23.0	12.5	11.4	8.7	8.2	8.8	2.0	2.6	2.5	2.8	2.0	1.1	F
MNRJ 72820	24.1	13.4	12.3	9.5	8.6	9.5	2.0	2.8	2.7	2.9	1.9	1.3	F