Mantidactylus

Knoll, Angelika, Köhler, Jörn, Glaw, Frank, Teschke, Meike & Vences, Miguel, 2007, Larval morphology in four species of Madagascan frogs of the subgenus Brygoomantis (Mantellidae: Mantidactylus), Zootaxa 1616, pp. 49-59 : 53-54

Mantidactylus sp. aff. betsileanus "very slow calls"

Series examined. ZSM 841/2004 (4 specimens) and 843/2004 (2 specimens) from An’Ala, ZSM 1114/2004 (1 specimen) and 1193/2004 (1 specimen) from Ranomafana, Maharira. Tadpoles from An'Ala were collected in ephemeral ponds of about three to five meters diameter, moderate depth and with a thick layer of dead leaves covering the ground. Sampling was carried out in January and February 2003 and February 2004.

Taxonomic note. This is a sibling species of M. betsileanus , differing morphologically by a different shape of femoral glands in adult males, and by a conspicuously slower pulse repetition rate in advertisement calls. Calls of this species are documented by Vences et al. (2006) on CD 2 as Track 64 (as M. sp. aff. betsileanus "very slow").

Description (based on a tadpole from series ZSM 841/2004, field number 2003.1604; Genbank accession number EF606879 ; Fig. 2 ). Tadpole in stage 25 and in fairly good state of preservation. Colouration in preservative is transparent tan with a yellowish shade. Dorsum uniformly coloured transparent yellowish, above each nare an orange coloured spot/structure shining through the skin, also visible in ventral view. Dorsal fin, belly and ventral caudal fin almost lacking darker flecks. In dorsal view, body shape elliptical. In lateral view, body depressed, BW 1.43 of BH. Body shape in lateral view flattening toward snout. Nostrils directed dorsolaterally, round, not protuberant, positioned closer to the tip of the snout than to the eyes, S– N 0.86 of N–E. Eyes positioned dorsally, oriented dorsolaterally, moderately sized, ED 0.07 of BL, not visible in ventral view. Snout rounded in lateral view, nearly rounded in dorsal view. Spiracle sinistral, closely attached to the body wall, slightly visible in dorsal view. Spiracular opening oval, upper margin situated approximately at level of lower margin of eye, at mid-distance between end of body and tip of the snout, S– S 0.51 of BL. Intestinal spiral well visible in lateral and ventral view, also visible in dorsal view. Short, flattened vent tube, almost median, cloacal opening dextral to caudal fin, attached directly to the ventral fin. Caudal musculature welldeveloped, upper origin well visible in dorsal view, TMH 0.61 of BH and 0.57 of MTH, gradually tapering from base to the rounded tip. Dorsal fin originating on base of caudal musculature, increasing in height at about half of length of tail, MTH 1.07 of BH, maintaining equal height throughout two-third of the tail, slightly diminishing to finely rounded tip. Dorsal and ventral fin slightly convex in outline, dorsal fin at its maximum height slightly higher than ventral fin, margins nearly parallel with the margins of the tail muscle. Oral disc small, generalized, ODW 0.28 of BL and 0.53 of BW, transversely elliptical, directed anterioventrally, laterally emarginated, not visible in dorsal view, but margins visible in lateral view. All but its anterior margin free from the body wall. Large dorsal gap, DG 0.57 of ODW, upper labium with 8 marginal papillae and one submarginal papilla on each side. Lower labium with two continuous rows of papillae (app. 50 in marginal row). All papillae with a rounded tip, less than 1.0 mm in length each. Keratodont row formula 1:4+3/3, about 60 keratodonts per mm. Keratodont row length reduces from A2 to A4, with A5 consisting of 4 keratodonts only on the left side of the oral disc. Large medial gap in second anterior keratodont row. Beak well developed and dark brown, both jaw sheaths with serrations at their cutting edges. Upper beak M-shaped, lower beak V-shaped.

Measurements (in mm): BL 7.5; TAL 14.4; TL 21.9; BW 4.0; BH 2.8; ED 0.5; IOD 2.0; IND 1.2; S– N 1.2; N– E 1.4; S– S 3.8; TMH 1.7; TMW 1.8; MTH 3.0; ODW 2.1; DG 1.2.

Variation within the series. The series ZSM 841/2004 and ZSM 843/2004 contain two undamaged tadpoles at stage 25 and one in stage 26. Proportions of stage 25 tadpoles vary as follows: BW 1.39–1.48 of BH, ED 0.07 of BL, S– N 0.93 –1.00 of N–E, IND 0.70 of IOD, S– S 0.48 –0.57 of BL, TMH 0.54–0.64 of BH, TMH 0.54–0.62 of MTH, MTH 1.00–1.04 of BH, ODW 0.27–0.28 of BL, ODW 0.51–0.54 of BW. Stage 26 differs by the following ratios: S– N 0.79 of N–E, IND 0.75 of IOD, S– S 0.63 of BL, TMH 0.52 of BH, TMH 0.45 of MTH, MTH 1.15 of BH, ODW 0.23 of BL, ODW 0.42 of BW (see Tab. 2 ). Keratodont row formula is not consistent, with larvae at stage 25 exhibiting keratodont row formulae 1:4+3/3, 1:4+4/3 and 1:3+3/3. The stage 26 larva has the keratodont row formula 1:3+4/3. General morphology and colouration is homogenous within the sample.

Previous descriptions. See discussion.

Figures

FIGURE 2. Drawings of the preserved voucher tadpole of Mantidactylus sp. aff. betsileanus " very slow calls " (stage 25), series ZSM 841 / 2004; (A) dorsal view, (B) lateral view, (C) oral disc.