Mantidactylus undetermined

Grosjean, Stéphane, STRAUss, Axel, Glos, Julian, Randrianiaina, Roger-Daniel, Ohler, Annemarie & Vences, Miguel, 2011, Morphological and ecological uniformity in the funnel-mouthed tadpoles of Malagasy litter frogs, subgenus Chonomantis, Zoological Journal of the Linnean Society 162 (1), pp. 149-183 : 172-173

MANTIDACTYLUS SP. 59

This is an undescribed species of Mantidactylus (Chonomantis) differing in external morphology of adults and in advertisement call that is currently being described taxonomically, and which was named Mantidactylus sp. 59 by Vieites et al. (2009). Its tadpoles differ from those of all other species of Chonomantis by the presence of what we interpret as rudimentary keratodonts on the lower labium (absent in all other species). Other morphological characters are extremely similar to all other species of Chonomantis , except M. aerumnalis which can be distinguished by its coloration.

The description of external morphology of the tadpoles of M. sp. 59 is based on the DNA voucher specimen in stage 27, ZSM 707/2007 (field number T0249; GenBank accession number GU808462 ) from stream ‘B100’ in Ranomafana National Park (TL 36.1 mm, BL 9.20 mm). A second specimen from the same batch, in stage 26, was used for the description of the tail, measurements and drawings (TL 34.1 mm, BL 9.02 mm). Buccopharyngeal features are described based on one tadpole at stage 27, ZSM 1079/2007 (field number ZCMV 4048; GenBank accession number

GU808451 ), a second specimen ZSM 1208/2007 ( ZCMV 5191 ; GU808457 ) was used for comparison .

External morphology: In profile ( Fig. 1 ), BW 127% of BH, snout truncate. In dorsal view ( Fig. 1 ), body widest at level of gills. ED 17% of BL. Pineal ocellus present between centre of pupils. Nares rounded, positioned almost dorsally, RN 60% of NP, NN 58% of PP. Spiracle as a short conical flat tube, entirely attached to body wall (inner wall present as a slight ridge sensu Altig & McDiarmid, 1999: 33, fig. 3.5), SS 50% of BL; spiracular opening oval, glued against body wall. Tail musculature, TMH 89% of BH and 86% of MTH, TMW 55% of BW, almost reaching tail tip. Tail fins, UF 26% of MTH, LF 22% of MTH, SU 104% of BL, lower fin straight and horizontal on most of its length then curved at its end to form the tip of tail; TAL 292% of BL, point of maximum height of tail located just after proximal third. Anal tube short, small, directed posterolaterally, linked to ventral tail fin except its distal half free. Lateral line organs present on body and tail.

Oral disc ( Fig. 2 ) moderately large, ODW 31% of BL and 44% of BW. Lower labium with a median notch sharing labium on a third of its length; the round structure on midline just behind median notch of same size than other papillae. Two small horizontal ridges between horizontal row of papillae and lower beak, on lower labium, bearing two black and pointed structures probably homologous to keratodonts. Upper jaw sheath light brown with black serrations.

Coloration in preservative: Upper side brown grey with small irregular dark brown markings; extension of caudal muscle on back beige. Upper part of flanks similar to back. Lower part of flanks translucent grey, almost unpatterned. Ventral side translucent grey, unpatterned, rectus abdominis and intestine visible through skin; very small dots few in number anteriorly to eyes. Upper and lateral parts of caudal muscle light beige covered with brown dots irregularly arranged forming more or less reticulations in anterior part, more numerous on upper part of the caudal muscle than on lower part; density of these spots decreasing from anterior part of tail towards its end. Ventral part ivory. Fins translucent grey, unpatterned except on proximal third of upper fin. Umbelliform oral disc with grey markings, especially on the small flaps forming the upper lip and on ridges and papillae.

Variation: Based on 13 other tadpoles, all from streams in Ranomafana National Park, at stages 25–31: ZSM 139/2007 (field number ZCMV 4343; GenBank accession number GU808450 ); ZSM 156/ 2007 (ZCMV 4350; GU808458 ); ZSM 300/2007 (ZCMV 4063; GU808461 ); ZSM 320/2007 (ZCMV 5150; GU808453 ); ZSM 587/2007 (ZCMV 5151; GU808454 ); ZSM 618/2007 (ZCMV 5383; GU808466 ); ZSM 793/ 2007 (T0262); ZSM 1009/2007 (ZCMV 4472; GU808460 ); ZSM 1079/2007 ZCMV 4084); ZSM 1109/ 2007 (ZCMV 4065); ZSM 1152/2007 (T0297); ZSM 1208/2007 (ZCMV 5191); and ZSM 93/2008 (ZCMV 4184; GU808456 ).

These tadpoles (TL 19.6–37.4 mm, BL 5.5–9.7 mm) vary in the following proportions: BW 109–142% of BH; ED 14–17% of BL; RN 46–67% of NP; NN 55–74% of PP; SS 42–56% of BL; TMH 53–83% of BH; TMH 54–73% of MTH; TMW 41–62% of BW; UF 24–32% of MTH; LF 23–28% of MTH; SU 93–129% of BL; TAL 225–298% of BL; MTH 95–138% of BH; ODW 29–37% of BL; ODW 39–55% of BW.

The number of ‘keratodonts’ is variable: 3 + 2 (ZSM 156 and 1079/2007, stages 31 and 27), 3 + 3 (ZSM 330/2007, stage 27), 3 + 4 (ZSM 1109/2007, stage 27), 4 + 3 (ZSM 139, 320, 587 and 618/2007, stages 26 and 27), 4 + 4 (ZSM 93/2007, stage 28), 4 + 5 (ZSM 793/ 2007, stage 25), 5 + 5 (ZSM 1009/2007, stage 25). The specimen ZSM 1152/2007 possesses neither ridges nor ‘keratodonts’. The number of ‘keratodonts’ does not seem to be linked to the developmental stage as in other tadpole species.

Buccal floor ( Fig. 3 ): Prelingual arena trapezoidal, two vertical ridges on inner side of lower beak; two pairs of small and simple prelingual papillae on same horizontal plane lying on lateral wall of the arena, directed medially. Tongue anlage prominent, elongate transversally and curved backwards; one pair of relatively long and simple lingual papillae posterodorsally orientated. Buccal floor arena triangular delimited by a row of 11–12 stocky and very small papillae on each side, the biggest in front of buccal pocket bearing two or three stubs, the two posteriormost the finest, orientated anterolaterally; interior of arena with some scarce and faint pustules. Buccal pockets narrow, curved and almost obliquely orientated; a longitudinal row of about seven prepocket papillae and some pustules in continuity with buccal floor arena papillae. Ventral velum with spicular support, bearing a blunt triangular projection above third filter plate, a very flat and large projection above second filter plate and four fine projections above first filter plate; no medial notch; glottis covered by velum except for its posterior end; no secretory pits visible. Branchial baskets wider than long, curved dorsally; with three filter cavities, filter plates obliquely arranged, filter mesh with main folds and some secondary folds.

Buccal roof ( Fig. 4 ): Prenarial arena rectangular, two vertical ridges on anterior wall following upper beak; one pair of flat and roughly oval prenarial papillae at posterior end of the ridges, ventrally orientated. Choanae moderately sized, transverse; anterior wall slightly elevated, smooth, bearing a simple fine and long papilla on lateral half; narial valve slightly elevated, forming a rounded flap wrapping medial extremity of choana with a ventrally orientated prominence at its extremity. A large, flat, and rounded flap behind each choana on a prominence, probably homologous to postnarial papilla. Postnarial arena without ornamentation. Median ridge arrow-like, with tip directed posteriorly. No lateral ridge papillae. Buccal roof arena diamond-shaped; two tiny buccal roof arena papillae on each side, the biggest anterior; interior of arena with faint pustules. Posterolateral ridge present and prominent, raised, not continuous across dorsal roof. Glandular zone present, absent medially, with relatively large secretory pits. Dorsal velum continuous through dorsal roof, elevated laterally. Pressure cushions not evident, maybe damaged during dissection.

Figures

Figure 1. Lateral and dorsal views of tadpoles of Mantidactylus belonging to the subgenus Chonomantis. Mantidactylus albofrenatus, specimen in stage 26 from the batch ZSM 420/2004. Mantidactylus brevipalmatus, specimen ZMA 7078 in stage 28. Mantidactylus delormei, specimen ZSM 440/2004 in stage 40 (coloration of specimen largely faded and therefore only outline drawn). Mantidactylus melanopleura, specimen ZSM 1318/2007 in stage 26. Mantidactylus opiparis, a specimen from the batch ZSM 416/2004 in stage 25. Mantidactylus zipperi, specimen ZSM 1825/2007 in stage 35. Mantidactylus sp. 59, specimen ZSM 707/2007 in stage 27. Scale bars = 10 mm.

Figure 2. Oral discs of tadpoles of Mantidactylus belonging to the subgenus Chonomantis. Mantidactylus albofrenatus, specimen in stage 26 from the batch ZSM 420/ 2004. Mantidactylus brevipalmatus, specimen ZMA 7080 in stage 27. Mantidactylus delormei, specimen ZSM 440/ 2004 in stage 40. Mantidactylus melanopleura, specimen ZSM 415/2004 in stage 25. Mantidactylus opiparis, specimen from the batch ZSM 416/2004 in stage 25. Mantidactylus zipperi, specimen ZSM 1821/2007 in stage 39. Mantidactylus sp. 59, specimen ZSM 707/2007 in stage 27. Note that the oral disc of M. sp. 59 is drawn in frontal view (all other drawings in dorsal view), and that it contains a row with a low number of keratodont-like structures. Scale bars = 1 mm.

Figure 3. Scanning electron microscopic pictures of buccal floor in tadpoles of Mantidactylus belonging to the subgenus Chonomantis. Mantidactylus albofrenatus, a specimen in stage 26 from the batch ZSM 420/2004. Mantidactylus brevipalmatus, specimen ZMA 6991 in stage 36. Mantidactylus zipperi, specimen ZSM 1824/2007 in stage 40. Mantidactylus sp. 59, specimen ZSM 1079/2007 in stage 27. Mantidactylus delormei, specimen ZSM 446/2004 in stage 36. Mantidactylus melanopleura, specimen ZSM 461/2004 in stage 38. Mantidactylus opiparis, specimen ZSM 422/2004 in stage 25. Scale bars = 1 mm.

Figure 4. Scanning electron microscopic pictures of buccal roof in tadpoles of Mantidactylus belonging to the subgenus Chonomantis. Specimens and stages as in Figure 3. Scale bars = 1 mm.