Osteology, skeletal development, and chondrocranial structure of Hamptophryne boliviana (Anura: Microhylidae).

Hamptophryne boliviana is a medium-sized microhylid frog inhabiting the forest-floor leaf litter of South American rainforests. Larvae of this species typically are found near the bottom of small ponds and water-filled depressions in the forest. On the basis of cleared-and-stained specimens, the larval chondrocranium is described, as well as the development of the skeleton and its condition in adults. Contrary to previous reports, adult Hamptophryne boliviana possess neopalatine (= palatine) bones. The vomer is divided into anterior and posterior parts; the degree of development of the posterior vomers varies among individuals and bilaterally within individuals. In its osteological development, Hamptophryne differs from most other anurans studied in that the vomer, and bones of the suspensorium and mandible, appear postmetamorphically. Similarly, the ischium, pubis, carpals, and tarsals do not appear until metamorphosis is completed. The chondrocranium possesses paired suprarostral cartilages-elements that have been reported to be absent in microhylid larvae. Furthermore, the chondrocranium differs from those described for other microhylid taxa by the possession of 1) a subpalatoquadrate bar that is described herein and 2) a greatly expanded, fenestrate sheet of cartilage associated with the larval otic process and otic capsule.