Morphology of premetamorphic larvae of Lysapsus limellus (Anura: Pseudinae)

Abstract

The chondrocranium, visceral skeleton, mandibular, hyoid and hyobranchial musculature, buccal apparatus and buccopharyngeal cavity of premetamorphic larvae of Lysapsus limellus from Santa Fe, Argentina are described. The cartilaginous skeleton corresponds in general terms to that of a typical pond type tadpole. Some characteristic features are the flat triangular projection of the arcus subocularis quadrati, the scarce development of the cartilagines orbitales, the presence of the processus pseudopterygoideus and quadratoethmoidalis, the open fenestra basicranialis, and the presence of a reticulating cartilaginous connection between the spicula III, IV and the plana hypobranchialia. Regarding muscles, the most salient characters are the configuration of the m. levator mandibulae lateralis, with nasal insertion, and the presence of a discontinuous m. subarcualis rectus II-IV. The oral disc and buccal cavity show features that indicate a generalist-mesophagous diet, for example the presence of jaw sheaths, rows of keratodonts, filter structures on the buccal floor and roof, and a glandular epithelium in the ventral velum.