Chondrocranial morphology and ossification of three species of Ptychohyla (Ampibia:Anura:Hylidae)

The genus Ptychohyla consists of eleven species of neotropical mountain stream-breeding tree frogs. Herein we report and compare anatomical larval characteristics for three species: P. salvadorensis, P. spinipollex and P. hypomykter. Chondrocranial anatomy and skeletal development were analyzed using tadpoles that were cleared and double-stained for bone and cartilage. The chondrocrania are similar, all having medially fused suprarostrals, larval otic processes, and cornua trabeculae representing about one-fifth of total chondrocranial length. At stage 25 P. salvadorensis possesses a well developed larval processus antorbitalis, which is poorly developed in the other species. Sequences of cranial and postcranial ossification are reported based on a complete developmental series of P. salvadorensis (23 tadpoles and juveniles); for the other species only incomplete developmental series were available and thus comparisons are made where possible. Ossification begins significantly later in P. hypomykter than in the other two species