Premetamorphic Development of the Phytotelm-Dwelling Toad Dendrophryniscus lauroi (Anura: Bufonidae).

The genus Dendrophryniscus, an early-diverging lineage of Bufonidae endemic to the Brazilian Atlantic Forest, includes 17 species of small toads with reproductive habits mostly linked to phytotelmata. Information about premetamorphic development in these species is very scarce, being restricted to observations on embryos of a single species and tadpoles of three. As part of a long-term project on the study of natural history and reproductive biology in Dendrophryniscus lauroi, this contribution describes premetamorphic morphology and development, and discusses the results in the context of what is known for the genus and other bufonids with similar breeding habits. Embryonic and larval stages of D. lauroi are similar to that of several pond-type bufonids, with common features such as dark pigmentation, Type-B adhesive glands, lack of dorsal curvature, and, in tadpoles, small size, labial tooth row formula 2/3, one pair of infralabial papillae, four lingual papillae, tri/tetrapartite suprarostral, larval otic process absent, and m. subarcualis rectus II-IV inserting posteriorly on ceratobranchial IV. Some heterochronic shifts during embryonic and metamorphic ontogeny concern the accelerated development of hind limbs and the delayed transformation of the larval oral morphology into the adult mouth configuration. While ecomorphological variation among phyotelm-dwelling anuran tadpoles is astonishing, most bufonid species exhibit the general aspect of pond-type larvae, with some modifications likely correlated with the lack of active feeding. These include reduction in mouthparts and a short gut filled with yolk, and are more pronounced in obligate endotrophic forms such as Frostius and Pelophryne, than in D. lauroi, where metamorphosis may occur with or without food supply. Phytotelm ecosystems are of increasing interest for ecological studies at multiple levels, and provide an exceptional setting to investigate community ecology and ecomorphological evolution in confined microhabitats.