Chondrocranial, hyobranchial and internal oral morphology in larvae of the basal bufonid genus Melanophryniscus (Amphibia: Anura)

Abstract

Melanophryniscus is a genus of small toads inhabiting the southern portion of South America. This genus is considered basal within the family Bufonidae. Data on larval chondrocranial morphology do not exist for the genus and larval internal oral anatomy has only been described for a single species. Here, we describe chondrocranial and internal oral morphology in Melanophryniscus montevidensis , M. orejasmirandai and M. sanmartini . Chondrocranial morphology is similar among the species examined. Comparisons with other bufonids and with outgroup taxa suggest that the following chondrocranial characters may represent synapomorphies for the Bufonidae: free (or absent) ceratobranchial IV, a reduced or absent larval crista parotica, the lack of a larval otic process, and late development of thin, poorly chondrified orbital cartilages. The presence of an elongated processus anterior dorsalis of the suprarostral alae and the absence of a chondrified commissura quadratoorbitalis appear to be unique in Melanophryniscus among bufonids. Internal oral anatomy is conserved in Melanophryniscus , and among bufonids in general.

Comparative morphology of pond, stream and phytotelm-dwelling tadpoles of the South American Redbelly Toads (Anura: Bufonidae:Melanophryniscus)

“…The basibranchial was fused to the hypobranchial plates; these latter were flat, wide, and articulate medially leaving a posterior triangular notch. In the posterior edge of each hypobranchial plate, a small mass of cartilage (possibly homologous to spiculum IV, according to Larson et al ., ) was evident (Fig. ).…”

“…Frost et al ., ; Van Bocxlaer et al ., ; Pyron & Wiens, ; Peloso et al ., ), and its monophyly, although still not tested rigourously, is suspected based on to available morphological, biochemical, behavioural, and molecular evidences (McDiarmid, ; Larson et al . ; Daly et al ., ; Toledo, Sazima & Haddad, ; Peloso et al ., ). Unfortunately, an inclusive phylogenetic analysis to assess internal relationships within the genus is lacking.…”

“…During the last few decades the taxonomic knowledge on the genus has increased significantly, but this situation has not been accompanied by a comprehensive understanding of other areas of their biology. Larval forms have been described formally in nine species (see http://onlinelibrary.wiley.com/doi/10.1111/bij.12296/suppinfo), but aspects of larval anatomy have been reported for only four of them (Echeverría, ; Haas, ; Larson, de Sá & Arrieta, ). The broad morphological and ecological variation in adult stages foresees a comparable diversity in larval development and biology once more taxa have been revised.…”

Chondrocranium and cranial muscle morphology in Lysapsus and Pseudis tadpoles (Anura: Hylidae: Hylinae)

“…With regard to the absence of copula anterior (character 5), an Alcian Blue-positive copula anterior occurs in P. cardosoi (stage 35) and in some specimens of P. p. occidentalis (stages 35 and 38). The intraspecific variation of this character was pointed out by several authors (Haas 1995;Larson et al 2003), and consequently we dismissed this character. We verified character 8 in L. limellum, P. cardosoi and P. paradoxa but not in P. minuta.…”

Complementary diagnosis of the genus Insuetophrynus (Anura, Cycloramphidae) based on larval characters

“…Three tadpoles at stages 26, 30, and 35 (IZUA 3743) were dissected for observation of the internal buccal anatomy with scanning electronic microscopy (SEM), following the methodology described by Larson et al (2003). Buccal cavity features were examined and photographed using scanning electron microscope (Leo-420) connected to a computer.…”