Different pathways are involved in the early development of the transient oral apparatus in anuran tadpoles (Anura: Leiuperidae)

Abstract

The oral apparatus of anuran tadpoles is a unique structure composed of soft and keratinized parts surrounding the mouth. Among the many variations, a common oral apparatus involves a dorsal gap in the marginal papillae, keratinized jaw sheaths, and two upper and three lower rows of labial teeth. In Leiuperidae, besides this generalized morphology, four configurations are distinguished by the arrangement of the lower marginal papillae and the number of lower tooth rows. Study of the early oral ontogeny in 12 species representing these five configurations shows variations in the development of the lower marginal papillae and the third lower labial tooth row. Similar configurations may result from similar pathways (e.g. Physalaemus cuvieri group and Pseudopaludicola falcipes) or different pathways (e.g. generalized oral discs of Pleurodema and Physalaemus). Different oral configurations may result from overlapping trajectories ending at different stages (e.g. Physalaemus riograndensis and Ph. biligonigerus) or different trajectories (e.g. Ph. henselii and Ph. gracilis). Further studies are needed to interpret the role that heterochrony has played in evolutionary change within this family. The unsuspected variation occurring in this transient structure highlights its evolutionary potential and might be insightful in studies of anuran phylogenies that are largely based on adult characters.

Phylogeny of frogs from the genus Physalaemus (Anura, Leptodactylidae) inferred from mitochondrial and nuclear gene sequences

“…The presence of this trait in P. nattereri was noted by Ananias et al (2007) and Kolenc et al (2011), and it was previously proposed as a synapomorphy of the P. Therefore, we tentatively assign them to the P. signifer Clade.…”

“…riograndensis maintains a configuration with ventrolateral gaps, tadpoles of the remaining three species have complete marginal papillae (Vera Candioti et al, 2011).…”

“…nebulosum and P. tucumanum;Cei, 1980), although the developmental processes involved differ (Vera Candioti et al, 2011). The presence of two lower labial tooth rows may represent, therefore, a synapomorphy of these species of Physalaemus and defines an oral disc that truncates its development with regard to the plesiomorphic larval labial tooth-row formula 2/3.…”

“…Subsequently, Lobo (1996) Physalaemus henselii and P. fernandezae were formerly included in the Physalaemus cuvieri Group by Lynch (1970) or in the P. henselii Group (with P. riograndensis) by Nascimento et al (2005). However, several works indicated that the larval configuration conflicts with the inclusion of P. riograndensis in these groups (Alcalde et al, 2006;Kolenc et al, 2006;Vera Candioti et al, 2011). Physalaemus henselii and P. fernandezae share with P. cicada the larval oral disc configuration that displays three lower labial tooth rows and marginal papillae with a ventral gap (C5 sensu Vera Candioti et al, 2011).…”

“…However, several works indicated that the larval configuration conflicts with the inclusion of P. riograndensis in these groups (Alcalde et al, 2006;Kolenc et al, 2006;Vera Candioti et al, 2011). Physalaemus henselii and P. fernandezae share with P. cicada the larval oral disc configuration that displays three lower labial tooth rows and marginal papillae with a ventral gap (C5 sensu Vera Candioti et al, 2011). This character combination of the oral disc is particular and, among the other leiuperines, was observed only in some specimens of …”