Vocal sac development and accelerated sexual maturity in the lesser swimming frog, Pseudis minuta (Anura, Hylidae)

GOLDBERG, J.; BARRASSO, D.; AGOSTINI, G.; QUINZIO, S. I.

ZOOLOGY

ELSEVIER GMBH

Año: 2016

0944-2006

Sexual maturity involves the differentiation of thereproductive system, the maturation of germ cells, and the development ofsecondary sexual characteristics. Even though this topic has receivedmuch attention, little is known about the sequence of events thatencompass reproductive maturation in anurans and what it could revealabout the developmental basis of life cycle evolution. The discovery offroglets of Pseudis minuta with incipient vocal sacs calling in breedingpools alongside several larger adult specimens with fully-developed vocalsacs raised the question of the timing of sexual maturity in thisspecies. Here we describe the sequence and timing of differentiation,development and maturation of the vocal sac apparatus and the testes inPseudis minuta (Anura, Hylidae), in order to establish a timeline ofevents leading to sexual maturity. Differentiation of the vocal sacapparatus begins at the final metamorphic stages, earlier than reportedfor other species, and the vocal sac acquires its final shape during theearly postmetamorphic period. These modifications occur after gonadaldifferentiation, which begins early during the larval period and proceedswith a highly accelerated rate of development (e.g., secondary spermatidsappear well before metamorphic climax), a situation reported previouslyfor other anuran species only in the genus Pseudis. These results,together with skeletochronological analysis showing that some callingspecimens presented no lines of arrested growth, indicate acceleration inthe timing of sexual maturity in Pseudis, and raise questions about theinterdependence/decoupling during development of the different componentsinvolved in reaching the adult stage.