Bokermannohyla diamantina

Pezzuti, Tiago Leite, Santos, Marcus Thadeu Teixeira, Martins, Sofia Velasquez, Leite, Felipe Sá Fortes, Garcia, Paulo Christiano Anchietta & Faivovich, Julián, 2015, The tadpoles of two species of the Bokermannohyla circumdata group (Hylidae, Cophomantini), Zootaxa 4048 (2), pp. 151-173 : 158-162

Bokermannohyla diamantina

External morphology. Maximum total length 46.1 mm (at stage 37; Table 1 ). Body depressed (BH/BW = 0.73– 0.77), ovoid in dorsal view, 0.31–0.32 times TL; in lateral view, ventral contour flat in peribranchial region and convex in abdominal region ( Fig. 6 A, B). Snout rounded in dorsal (BWN/BWE = 0.72–0.79) and lateral views. Eyes medium-sized (ED/BWE = 0.21–0.22), dorsally located (IOD/BWE = 0.68–0.71), dorsolaterally directed. Nostrils elliptical, medium-sized (ND/BL= 0.025–0.036), dorsally located, dorsolaterally directed, distance to snout 47–52% eye-snout distance; elevated marginal rim, with well-developed triangular or small round fleshy projection on the medial margin, irregularly scalloped on lateral margin ( Fig. 6 E, F). Spiracle sinistral, lateral (SVD/BH = 0.47–0.65), posterodorsally directed, short (SL/BL = 0.05–0.07), opening at the middle third of the body (SSD/BL = 0.52–0.60); internal wall fused to the body, with distal portion free and longer than the external wall ( Fig. 6 D).

Intestinal tube circularly coiled, switchback point located at center of abdominal region ( Fig. 6 C). Vent tube dextral, posteriorly directed, slightly wider than long ( Fig. 6 G), fused to the ventral fin and positioned at its ventral margin. Oral disc medium-sized (ODW/BW = 0.25–0.30), ventrally positioned, with three posterior emarginations ( Fig. 7 ); 130-138 conical marginal papillae arranged in a single row, with its bases offset throughout the oral disc; narrow anterior gap present (about 0.15 of ODW); submarginal papillae absent; LTRF 2(2)/3(1), A2=A1, P1=P2>P3; gaps in A-2 and P-1 about 0.3 and 0.02 mm, respectively; tooth density on P1 37–44 teeth/mm; absence of flaps with labial teeth laterally in the oral disc; jaw-sheaths wide, pigmented, finely serrated on the margins (20 to 24 triangular serrations on the upper jaw), upper jaw-sheath arc-shaped and lower jaw sheath Vshaped, upper wider than lower. Tail low (MTH/TAL = 0.27–0.30); musculature robust (TMH/BH = 0.51–0.58); dorsal fin higher than ventral fin (DFH/VFH = 1.26–1.36); tail tip acute. Dorsal fin low (DFH/TAL = 0.09–0.10), with a slightly convex external margin; emerging at posterior third of the body with a low slope; maximum height at posterior third of tail. Ventral fin low (VFH/TAL = 0.07–0.08), with the external margin almost parallel to the longitudinal axis of the tail musculature; originates at base of tail, concealed by vent tube. Lateral line system distinct in preserved specimens ( Fig. 8 ). All lines with transversally oriented stitches composed of two or three neuromasts. Supraorbital line with 14–17 stitches converging anteriorly on head, medial to nares, approaching the infraorbital series of 12–14 stitches. Infraorbital line begins behind eyes, extends anteriorly and is slightly curved in lateral profile ( Fig. 8 A, B). Posterior infraorbital line consists of a small aggregate series of seven to nine stitches with no clear organization. Posterior supraorbital line composed of three stitches located near posterior portion of the supraorbital line. Angular line with 16–20 stitches, extends from below eyes to venter ( Fig. 8 A). Anterior oral line with 11–12 stitches, extends from lateral region of oral disc and approaches region of angular line, ventrally. Longitudinal oral line with 7–8 stitches, located between anterior region of anterior oral line and angular line. Two series of lines extend from the mid body posteriorly throughout tail length ( Fig. 8 B): the first, dorsal line, with 16– 18 stitches, located medially, converging abruptly before body-tail junction and continuing posteriorly with 10–18 stitches along dorsal fin base, until end of tail ( Fig. 8 C); the second, middle-body line, with 18–21 stitches located laterally, joins the middle caudal series with 38–40 stitches. Along the approximate first third of tail this middle series projects dorsally reaching the dorsal fin base. A ventral body-line of 45–48 stitches extends anterodorsally from near vent tube forming a semicircle around the spiracle, and after a small gap without neuromasts continues posteroventrally until mid abdominal region. A cumulus of neuromasts is present anterolateral to base of vent tube, near ventral line ( Fig. 8 D).

Coloration. In 10% formalin, general pattern uniformly brown ( Fig. 6 ). Body with regularly scattered black spots; distal margin of spiracle lightly pigmented. Tail musculature densely marbled by irregular dark spots mainly on posterior half; a longitudinal dark stripe starting from posterior end of body and extending posteriorly along medial caudal muscle line, for first anterior 1/3 of tail; dorsal margin of caudal musculature with an interrupted or continuous narrow brown line; dorsal and ventral fins densely marbled by irregular spots mainly on anterior portion of dorsal fin.

Variation. Two specimens in stage 29 have an elliptical body in dorsal view. Four specimens in stages 34–36 have few submarginal papillae (1–2) laterally in the oral disc ( Fig. 7 B). The shape of the fleshy projections on the medial and lateral nostril margins is variable, even within the same specimen (i.e., right/left nostrils). There is no clear pattern of ontogenetic change in these characters.

Natural history notes. Tadpoles of Bokermannohyla diamantina are benthic and were found in shallow puddles (lotic environment) associated with water springs of high elevation mountain streams (i.e., 1688 m a.s.l. at Serra do Itobira), in swampy grasslands (open environment), close to narrow gallery forest edges or small islands of arborescent vegetation. Grasslands were covered manly by Graminaceae, Euryocaulaceae, Xyris (Xyridaceae) , and Apiaceae . These sites are surrounded by campos rupestres (rocky fields), a mosaic of habitat types including exposed grasslands, rock surfaces, cerrado, and small forests. Although we only collected tadpoles in the open grassland habitats, calling males were also found in these open areas and their associated forest habitats mainly on the ground or perched on vegetation. Adult calling activity was recorded in December and January at the beginning of the hot and rainy season (other months were not sampled).

Oral cavity morphology. Buccal roof —roof triangular, about 1.1 longer than wide ( Fig. 9 A). Two or three prenarial arena papillae with undulated margins, irregularly distributed or forming a longitudinal ridge along prenarial arena midline. Maximal internal nares length about 35% of BRW; internarial distance about 10% of BRW. Nares oriented 45º from midline; anterior wall short and thick with irregular margin; posterior wall (narial valves) large, wide and with distinct papillae; narial valves extending forward, covering almost completely the internal nares, and about half of the vacuities. Large elliptical, smoothly concave, and shallow vacuities attached anteromedially to internal nares. Postnarial arena with two or three pairs of papillae distributed in an inverted Vshape, with posterior and external papillae larger than those more anterior and medial; six to ten randomly distributed pustulations present. Median ridge rounded to triangular with three to eight blunt, short papillae on anterior surface. One pair of medium-sized lateral ridge papillae with three to four secondary projections. BRA hexagonal with 13–20 short buccal roof arena papillae distributed mainly posterolaterally. In addition, 8–11 digitiform lateral roof papillae on each side. BRA with 370–430 homogeneously distributed pustulations. Secretory pits distinct in glandular zone, mainly posterolaterally in the dorsal velum. Dorsal velum large, discontinuous at midline (gap corresponding to 28% of BRW); irregular, discrete marginal papillae present. Buccal Floor — floor triangular, as wide as long ( Fig. 9 B). Two pairs of infralabial papillae; one large, hand-like papillae located anteriorly, and one pair of short digitiform papillae posteriorly. One pair of tall, digitiform lingual papillae present. BFA triangular, surrounded by 44–50 long, digitiform papillae. These papillae are disposed in two rows, one medially from anterior region of buccal pockets to median region of BFA, and one extending laterally and more obliquely following the anterior margin of ventral velum, towards the posterior region of BFA; larger papillae located anteriorly; two or three large papillae bi or trifurcated. BFA with 169–195 pustulations, more concentrated posteriorly. Buccal pockets about 8 times wider than high, transversally oriented, deep, width about 25% of BFW. Four to seven conical prepocket papillae on each side; few (2–3) short prepocket papillae lying on the anterior wall of pocket. Ventral velum height about 30% of BFW. Posterior margin scalloped, with eight distinct peaks over filter cavities; peaks 8% of BFW; median notch depth about 7% of BFW. Secretory pits distinct when stained with methylene blue, more concentrated on posterior margin of ventral velum but absent on median notch region. Glottis large, 20% visible, width about 6% of BFW; thick and broad lips.

Figures

FIGURE 6. Bokermannohyla diamantina (UFMG 1060) at stage 37: (A) lateral, (B) dorsal, and (C) ventral views. Scale bar = 10 mm. Details of (D) spiracular aperture, (E, F) margin of left nostril with well-developed triangular and small round fleshy projections, respectively. Scale bars = 0.5 mm. (G) Vent tube of a specimen at stage 35. Scale bar = 1 mm.

FIGURE 7. Oral disc of Bokermannohyla diamantina (UFMG 1060): (A) a typical oral disc of a specimen at stage 37. (B) Presence of few submarginal papillae laterally in the oral disc of a specimen at stage 36. Scale bars = 1 mm.

FIGURE 8. The lateral line system of Bokermannohyla diamantina (UFMG 1060) in a stage 38 specimen. (A) Lateral view of body indicating the angular (AN), infraorbital (IO), longitudinal oral (LOR), anterior oral (AOR), posterior supraorbital (PSO), and ventral (V) lines. Scale bar = 2 mm. (B) Dorsal view of body showing the supraorbital (SO), infraorbital (IO), posterior infraorbital (PIO), middle (M), and dorsal (D) lines. Scale bar = 2 mm. (C) Detail of the tail and the courses of the dorsal (D) and middle (M) lines. Scale bar = 10 mm. (D) Detail of vent tube region of the body showing the ventral line of neuromasts (V), and, encircled, the associated ventrolateral cumulus of neuromasts (N). Scale bar = 1 mm.

FIGURE 9. SEM micrographs of oral roof (A) and floor (B) of Bokermannohyla diamantina at stage 35 (UFMG 1060). Scale bars = 2 mm. (1) Detail of the anterior region of roof: prenarial arena papillae (prnp); anteromedial vacuity of internal nares (amv); internal nares (in); narial valve projection (nvp); lateral ridge papilla (lrp); median ridge (mr); postnarial papillae (ptnp). (2) Detail of the posterior region of roof: lateral roof papillae (lrp); buccal roof arena (bra); buccal roof arena papillae (brap); dorsal velum (dv); secretory pits (sp). (3) Detail of the anterior region of floor: infralabial papillae (ilp); lingual papillae (lpa); lingual anlage (la); buccal pocket (bp); prepocket papillae (ppp). (4) Detail of the posterior region of floor: buccal floor arena (bfa); buccal floor arena papillae (bfap); vv (ventral velum); median notch (mn); glottis (g). Scale bars = 1 mm.