Mantidactylus ambreensis, Mocquard, 1895

dos Santos Dias, Pedro Henrique, Vera Candioti, Florencia, Wassersug, Richard, Lukas, Paul, Targino, Mariane, Glos, Julian, Wheeler, Ward C, Hertwig, Stefan, Crottini, Angelica & Haas, Alexander, 2024, Stranger things: on the novel buccopharyngeal anatomy and functional morphology of ‘ sand-eating’ Malagasy tadpoles (Anura: Mantellidae: Mantidactylus), Zoological Journal of the Linnean Society 202 (2), pp. 1-13 : 2-4

Mantidactylus ambreensis

Oral disc: Tadpoles of this species are not formally described, and only a few features of the oral disc, mostly from the upper lip, are evident in SEM micrographs. The upper lip is bordered by a single row of conical, alternate marginal papillae, and the inner surface is covered with small, conical, submarginal papillae. The labial tooth row formula (LTRF) could not be assessed, but two rows of labial teeth are present in the upper lip, a long row A1 and A2 as two short sections separated by a wide gap. Labial teeth are short, with four to eight long, distal cusps ( Fig. 2A ). The upper jaw sheath was not visible in micrographs, and the lower sheath is V-shaped and marginally serrated (Fig. 2B).

Buccal floor (Fig. 2B, C): Buccal floor triangular, caudally wider. Three pairs of tall, conical infralabial papillae overlapping each other. Tongue anlage wide, elliptical, with bulging lateral regions; medially, one pair of conical, tall, lingual papillae with bifid tips. Buccal floor arena delimited by two long, thick crests formed of approximately 15 transverse ruffled ridges closely spaced (100– 350 µm long, 95–140 µm wide); these ridges are apparently formed of densely packed papillae, distally wider, with a pustulated surface giving them a cauliflower-like appearance, more elaborate rostral than caudally; crests get closer caudally but do not meet medially. Caudal half of the central area of buccal floor arena covered by rounded, short pustulations densely arranged. Buccal pockets slit shaped, deep, oriented obliquely. Ventral velum very short medially, arch-shaped, with long marginal projections, deep median notch, and secretory pits on the margin; spicular support evident. Branchial basket triangular, shallow, with three filter cavities. Branchial plates with a mesh of filter rows visible under the caudal margin of the ventral velum. Glottis fully exposed.

Buccal roof ( Fig. 2D ): Buccal roof triangular, longer than wide. Prenarial arena triangular, with a wide inverted-V crest with pustulated margin and scattered small pustulations. Internal nares large and subcircular, forming shallow vacuities covered with cilia; margins thick and mostly smooth, with a short, finger-like papilla at the anteromedial corner, and a long, flap-like, pustulated papilla at the anterolateral edge; posterior margin mostly concealed by a tall, wide, triangular postnarial arena papilla anteriorly directed. Median ridge triangular, wide, and with crenulated free margin. Lateral ridge papillae absent. Buccal roof arena delimited by two parallel crests of c. 25 packed individual papillae distally pustulated, longer and more elaborated at the middle portion, and shorter and simpler anterior and caudally. Central area of buccal roof arena covered by short, rounded pustulation, denser caudally. Glandular zone with secretory pits arranged in a band anterior to the dorsal velum. Dorsal velum long, medially discontinuous, with medial margins and caudal surface covered by small pustulations and short, finger-like papillae.

Figures

Figure 2. Oral disc and buccopharyngeal morphology of Mantidactylus ambreensis (ZSM 755/2004). A, detail of the upper lip, showing keratinized teeth of row A1. B, detail of the anterior region of the buccal floor, showing the keratinized and serrated lower jaw sheath, and infralabial and lingual papillae.C, buccal floor; note the unique crest-like structures delimiting the buccal floor arena, formed of transverse ruffled ridges composed of ‘cauliflower-like’ papillae.D, buccal roof; note the large narial vacuities with ornamented anterior and posterior margins, and the buccal roof arena papillae tightly aligned in two longitudinal crests. Abbreviations: bfa, buccal floor arena; bra buccal roof arena; brap, buccal roof arena papillae; dv, dorsal velum, gl, glottis; ilp, infralabial papillae; in, internal nare; ljs, lower jaw sheath; lp, lingual papillae; mr, median ridge; pnr, prenarial ridge; rr, ruffled ridges; vv, ventral velum.Scale bars: 100 µm (A, B),200 µm (C, D).