Scaphiophryne brevis (Boulenger, 1896)

Grosjean, Stéphane, Glos, Julian, Teschke, Meike, Glaw, Frank & Vences, Miguel, 2007, Comparative larval morphology of Madagascan toadlets of the genus Scaphiophryne: phylogenetic and taxonomic inferences, Zoological Journal of the Linnean Society 151 (3), pp. 555-576 : 565-566

SCAPHIOPHRYNE BREVIS (BOULENGER, 1886)

Specimens were collected from a large puddle (c. 5 × 2 m) beside the street in the city of Toliara. The water was very warm and muddy. The external morphological description is based on two specimens at stage 31, ZSM 617/2004 and ZSM 618/2004, the tail of the former served for DNA determination, the second for verification, calculation of the ratios, tail description and drawings ( TL and BL are 18.5 and 6.8 mm, respectively). Buccopharyngeal features are described on the basis of one tadpole at stage 31 ( ZSM 619 /2004) .

Additional specimens assigned to this species (ZSM 631/2004–644/2004) were collected from a pond beside the street within spiny forest, beside the road between Ambovombe and Tolagnaro. The bottom of this pond was completely covered with grass and the water was very warm. These tadpoles were not used for the following detailed description but one of them was photographed ( Fig. 5 ).

External morphology: In dorsal view ( Fig. 1G ), body ovoid, widest at the level of gills, snout truncate. In profile ( Fig. 1H ), body depressed, almost flat above and below, BW 104% of BH, snout small, vertical and directed slightly upward. Eyes moderately small, ED 10% of BL, very slightly bulging (caused by the presence of a space between the outer integument and the organs), not visible in ventral view, positioned more dorsally than dorsolaterally and directed almost laterally. Nares not open, positioned dorsally, at the same distance to pupils than to snout, RN 100% of NP, very close to each other, NN 29% of PP. Spiracle sinistral but very low, tubular, moderately sized, entirely attached to body wall, inner wall absent, orientated posteriorly, slightly closer to end of body than to tip of snout, SS 59% of BL; spiracular opening a slit not clinging to the body wall, on a plane situated between the insertion of hindlimb and the opening of ventral tube. Tail musculature moderate, TMH 39% of BH and 36% of MTH, its maximum height reached before the proximal third then gradually tapering, not reaching tail tip. Upper fin moderately sized, UF 31% of MTH, convex, extending onto body, SU 70% of BL, lower fin moderately high, LF 38% of MTH, horizontal on the first third then straight toward tail tip before forming a rounded tip; point of maximum height of tail located between the proximal quarter and the midway of the tail length, MTH 108% of BH, tail tip round. Ventral tube moderately sized, medial, curved tubular, directed posteroventrally, entirely included in ventral tail fin, opening medial. Neither lateral line organs nor glands visible.

Oral disc ( Fig. 2J ) small, in position and orientation almost terminal, emargination very low, ODW 20% of BL and 29% of BW. An uninterrupted row of marginal papillae; three submarginal papillae separated from the row of marginal papillae on each side on the upper labium, DG 40% of ODW, a row of submarginal papillae separated from the row of marginal papillae on the lower labium; papillae of moderate size, conical with pointed tip, submarginal papillae claw-shaped. No denticulate papillae. No keratodonts. Jaw sheaths very finely serrated, white; upper jaw sheath a large arch, flat on the most part; lower jaw sheath V-shaped.

Coloration in preservative: Anterior part of upper side pigmented with brown, especially on the extension of caudal muscle on the back to an area between the eyes, digestive tract heavily pigmented with small brown spots. Flanks immaculate, digestive tract heavily pigmented with small brown spots. Ventral side immaculate. Caudal muscle pigmented with small brown spots. Fins immaculate.

Variation: The ratios taken on 11 tadpoles at stages 28–33 (ZSM 619/2004-ZSM 629/2004) vary in the following proportions: BW 108–125% of BH; RN 86–121% of NP; NN 23–33% of PP; SS 54–58% of BL; TMH 33–42% of BH; TMH 33–42% of MTH; UF 28–33% of MTH; LF 34–40% of MTH; SU 51–76% of BL; MTH 94–111% of BH; ODW 17–20% of BL; ODW 24–34% of BW; DG 34–57% of ODW.

Buccal floor ( Fig. 2K ): Prelingual arena very narrow, gutter-shaped; a pair of small prelingual papillae on the lateral wall of the arena, directed medially, another pair posterolaterally; a single medial curved gutter-shaped papilla originating just anterior to tongue anlage, directed dorsally, its distal part bearing three pustulate projections (one posterior and two lateral), a small projection on the posterior side. Tongue anlage prominent, without lingual papillae. Buccal floor arena oval delimited anterolaterally by a small papilla on each side of the arena, by a papilla lateral to buccal pocket and posteriorly by a transversal row of more than 15 papillae, the largest lateral; interior of arena smooth. A half circle (the convexity anterior) consisting of five median pustules just behind the row of papillae, the centre of this hypothetical circle occupied by a papilla just in front of the glottis. Buccal pockets wide, deep, transversely orientated, unperforated; two small prepocket papillae. Ventral velum with spicular support, bearing four projections on each half, the most developed above the second filter plate, two above the third filter plate, the smaller of two median; velum interrupted medially by the glottis; secretory pits present on the second projection. Branchial baskets oblique, wide, with three filter cavities, filter plates obliquely arranged, filter mesh very dense with tertiary folds.

Buccal roof ( Fig. 2L ): Prenarial arena small and round, with a small median transversal ridge bearing two pustules. Choanae large, drop-shaped; anterior wall slightly elevated, pustulate, without papilla; narial valve greatly enlarged posteromedially into a triangular, elongate, large structure with pustulate lateral edge, dorsally and anteromedially directed, covering the posterior end of the choana. Postnarial arena small and flat, without ornamentation. Median ridge triangular. One pair of triangular lateral ridge papillae, pustulate on top, posterolateral to the narial valves. Buccal roof arena non-existent, pustulations scattered within, more densely posteriorly, buccal roof arena papillae absent. Posterolateral ridges slightly elevated, present laterally. Glandular zone well developed, continuous throughout the buccal roof, formed by about six secretory pits wide. Dorsal velum smooth, interrupted medially on about one-quarter of its length, secretory pits present on its ventral side. Two pressure cushions on each side.

Figures

Figure 1. Dorsal and lateral views of tadpoles of Scaphiophryne madagascariensis (stage 35, ZSM 595/2004) (A, B), S. menabensis (stage 35, ZSM 413/2004) (C, D), S. spinosa (stage 29, ZSM 604/2004) (E, F), S. brevis (stage 31, ZSM 618/ 2004) (G, H) and S. calcarata (stage 31, ZSM 410/2004) (I, J). Scale bars represent 5 mm.

Figure 2. Oral disc (OD), buccal floor (BF) and buccal roof (BR) of tadpoles of Scaphiophryne madagascariensis (OD: ZSM 600/2004; BF, BR: stage 38, ZSM 599/2004) (A–C), S. menabensis (OD: stage 36 BF, BR: stage 36); all from specimens in batch ZSM 413/2004) (D–F), S. spinosa (OD: stage 28, ZSM 616/2004; BF, BR: stage 29, ZSM 612/2004) (G–I), S. brevis (OD: stage 34; BF, BR: stage 31, ZSM 619/2004) (J–L) and S. calcarata (OD: stage 34; BF, BR: stage 32; both from specimens in batch ZSM 410/2004) (M–O). Scale bars are indicated on the images.

Figure 5. Lateral, dorsal, and ventral views of a tadpole of Scaphiophryne brevis (ZSM 632/2004) showing the typical morphology of the relatively small tadpoles of the Scaphiophryne (Pseudohemisus) type.