Chondrocranial morphology and cranial ossification in the genus Leptodactylus (Amphibia: Anura: Leptodactylidae)

Frogs of the genus Leptodactylus are distributed throughout the neotropics. The genus consists of four distinct species groups: the fuse us group, ocellatus group, melanonotus group, and pentadactylus group. Chondrocrania! morphology of leptodactylid frogs is scarcely known and skeletogenesis has yet to be described for any species within the genus Leptodactylus. Herein, we describe chondrocrania! anatomy of seven species of Leptodactylus (representing the four species groups). Wild-caught tadpoles were fixed and subsequently cleared and double stained for bone and cartilage using standard procedure. Cranial ossification sequence is reported based on a complete developmental series (34 tadpoles and juveniles) of L. ocellatus. All examined species possess a chondrified commissura quadratoorbitalis and lack a larval otic process. A processus brachialis between ceratohranchial II and III is present in the ocellatus and melanonotus groups. The suprarostral has clearly identifiable corpora and alae in all species, except L pentadactylus which also differs from the other species in the size and shape of the cornua trabeculae. Cranial ossification sequence for L. ocellatus is overall similar to those reported for other species