Mantidactylus alutus (Peracca)

Schmidt, Heike, Glaw, Frank, Teschke, Meike & Vences, Miguel, 2009, Description of tadpoles of five frog species in the subgenus Brygoomantis from Madagascar (Mantellidae: Mantidactylus), Zootaxa 1988, pp. 48-60 : 56-58

Mantidactylus alutus (Peracca)

Series examined. ZSM 1482/2007 (1 specimen; field number FGZC 2212), ZSM 1490/2007 (6 specimens; field number FGZC 2221), ZSM 562/2008 (2 specimens; field number FGZC 2224), and ZSM 1492/2007 (9 specimens; field number FGZC 2225) all collected in an unspecified water body in a small forest near the main campsite, by L. Raharivololoniaina and R.-D. Randrianiaina, at Ambohitantely Special Reserve on 18–19 January 2005. ZSM 945/2004 (1 specimen; FG/MV 2002.1759), ZSM 946/2004 (1 specimen; field number FG/MV 2002.1761), ZSM 947/2004 (1 specimen; field number FG/MV 2002.1762) and ZSM 949/ 2004 (1 specimen; field number FG/MV 2002.1764), all from a site near Antoetra, collected in the period of 18–22 January 2003 by M. Vences (for a habitat description, see section on M. curtus above).

Taxonomic note. Tadpoles of M. alutus were previously described by Boulenger (1918) and Blommers- Schlösser (1979). According to our mitochondrial DNA data, M. alutus is genetically homogeneous across its distribution range (Glaw & Vences 2007; see also sequences available from Genbank), and the previous descriptions thus are likely to be correctly assigned to this species. We here complement previous data with more details, and with information on additional populations. The data of Blommers-Schlösser (1979) referred to pooled samples from several localities (Angavokely, Antananarivo, Manjakatompo). We additionally provide morphological data referring to tadpoles from Ambohitantely and Antoetra (see table 1).

Description. Based on the DNA voucher tadpole from series ZSM 1490/2007 (field number FGZC 2221; Genbank accession number EU717886 ; Figure 5 ). Specimen in developmental stage 40, and in good state of preservation (the whole right hindlimb has been excised for DNA analysis). BL 15.5 mm, TL 51.5 mm, for further measurements see Table 1 . Colouration in preservative throughout brownish with a grey transparent shade through skin, and dark irregular spots in dorsal and lateral view, with light brown irregular spots, and dorsally with a lack of dark spots at mid-body. A dark brown coloured linear structure shines through the skin, dorsally, from each nare to the eyes, not visible in ventral view. Belly and two-thirds of ventral caudal fin almost lacking these darker spots. In dorsal view, body shape ovoid. In lateral view, body depressed-elongated and shape slightly flattening toward snout, BW 1.20 of BH. Nostrils directed dorsolaterally, rounded, slightly protuberant, positioned at equal distance between tip of the snout and eyes, IND 0.56 of IOD. Eyes positioned dorsally, orientated dorsolaterally, not protuberant, moderately sized, ED 0.12 of BL, not visible in ventral view. Snout nearly pointed in lateral view, rounded in dorsal view. Spiracle single, sinistral, attached to the body wall, with inner wall free from body wall at the tip. Spiracular opening oval, oriented posteriorly, situated closer to the end of the body than to the snout, ESD 0.33 of BL. Intestinal spiral well visible in ventral and lateral views, only a dark brown shadow of it visible in dorsal view. Flattened vent tube, right wall displaced dorsally. Caudal musculature strong developed, upper origin well visible in dorsal view, TMH 0.93 of BH and 0.78 of MTH, gradually tapering from base to slightly pointed caudal muscle tip. Dorsal fin originating behind base of caudal muscle, slowly increasing in height, MTH 1.17 of BH, slightly diminishing to tip. Dorsal and ventral fin slightly convex in outline, dorsal fin at its maximum height slightly higher than ventral fin. Oral disc small, generalized, ODW 0.34 of BL and 0.57 of BW. Transversely elliptical, directed anteroventrally, laterally emarginated, not visible in dorsal view, but margins visible in lateral view. Large dorsal gap of marginal papillae, lower labium with two continuous rows of papillae. Papillae with a rounded tip and some pointed. Total number of papillae 92, some of them pigmented. LTRF 4(2–4)/3(1), with an additional small gap in row P3, here interpreted as oral deformity. About 36 teeth per mm and a total of 104 teeth in A2. Tooth row lengths decrease from A1 to A4, with A4 consisting of 13 teeth only on the right side of the oral disc. Large medial gap in second anterior tooth row and a large dorsal gap. First and third posterior tooth rows with small medial gap.

Beak well developed and dark brown, both jaw sheaths with serrations at their cutting edges, with three parts having different colourations: base, entirely keratinised, black; middle part, partially keratinised, brown; outer edges, not keratinised, unpigmented. Upper jaw sheath M-shaped, lower jaw sheath V-shaped.

Variation. To summarize variation we grouped specimens from all series based on their developmental stages. Seven tadpoles were in stages 25–28: stage 25 (3 specimens), 26 (1 specimen), 28 (3 specimens). Proportions: BW 1.03–1.56 of BH, IND 0.26–0.67 of IOD, ED 0.08–0.13 of BL, ESD 0.29–0.43 of BL, TMH 1.05–0.68 of BH, TMH 0.72–0.97 of MTH, MTH 0.97–1.31 of BH, ODW 0.28–0.37 of BL, ODW 0.51–0.73 of BW, TAL 1.58–2.19 of BL, BL 0.31–0.39 of TL, TAL 0.61–0.69 of TL. LTRF: 3(2–3)/3(1); 3(2–3)/3(1); 4(2–4)/3(1). Labial teeth per mm in A2: 24–41. Number of papillae: 59–105.

Thirteen additional tadpoles were in stages 31–40: stage 31 (2 specimens), 37 (3 specimens), 39 (2 specimens), 40 (6 specimens), Proportions: BW 1.14–1.83 of BH, IND 0.37–0.74 of IOD, ED 0.08–0.20 of BL, ESD 0.27–0.54 of BL, TMH 0.67–1.14 of BH, TMH 0.49–1.11 of MTH, MTH 0.89–1.72 of BH, ODW 0.29–0.68 of BL, ODW 0.48–0.62 of BW, TAL 1.58–2.49 of BL, BL 0.20–0.33 of TL, TAL 0.65–0.80 of TL. LTRF: 4(1–4)/3; 4(1–4)/3(1); 4(1–4)/3(1)(3); 4(2–4)/3; 4(2–4)/3(1); 4(2–4)/3(1)(3) (small non-medial gaps in some specimens in A1, here interpreted as oral deformities). Number of labial teeth per mm in A2: 27–43. Number of papillae: 75–121.

One tadpole was in developmental stage 42: Proportions: BW 1.02 of BH, IND 0.48 of IOD, ED 0.13 of BL, ESD 0.32 of BL, TMH 0.89 of BH, TMH 0.69 of MTH, MTH 0.29 of BH, ODW 0.31 of BL, ODW 0.74 of BW, TAL 2.20 of BL, BL 0.31 of TL, TAL 0.68 of TL. LTRF: 4(1–4)/3(1). Number of labial teeth per mm in A2: 30. Number of papillae: 76.

The tadpoles of M. alutus show a distinct correlation of the number of labial tooth rows and developmental stage: younger tadpoles (stages 25–26) had constantly three upper tooth rows, whereas in stages 28–40, an additional upper tooth row was visible in all specimens.

In earlier stages the skin is more transparent and less grey to more yellowish brown. A small gap in row P3 was observed in several specimens of earlier as well as advanced stages and is here interpreted as oral deformity.

Figures

FIGURE 5. Drawings of the preserved DNA voucher tadpole of Mantidactylus alutus (stage 40), series ZSM 1490 / 2007; (a) oral disc, (b) dorsal view, (c) lateral view. Scale bars represent 1 mm.