Embryonic morphology in five species of the genus Hypsiboas (Anura: Hylidae)

NAVARRO ACOSTA GRISEL; BALDO DIEGO; BORTEIRO CLAUDIO; KOLENC FRANCISCO; VERA CANDIOTI MARÍA FLORENCIA

HERPETOLOGICAL JOURNAL

BRITISH HERPETOL SOC

Lugar: Montrose, Angus, UK; Año: 2017

0268-0130

Research concerning the early development of anuran tadpoles has sparked new interest, ever since comparative studies revealed structural and temporal variations of embryonic stages within different taxonomic groups. In this paper we studied the early ontogeny of five species of the hylid genus Hypsiboas: H. curupi, H. pulchellus, H. riojanus, and H. sp. from the H. pulchellus group, and H. faber from the homonymous group. We analyze comparatively the development of typical larval structures (oral disc), and of embryonic transient structures (external gills, ciliated cells, hatching glands, and adhesive glands). Results show that the diversity in structural patterns is mainly related with the number and size of external gills, size of the adhesive glands, ciliation density, and number of labial tooth ridges. In turn, heterochronic shifts mostly concern the time of adhesive gland division, and the regression of the hatching gland and ciliated cells. In some cases these variations appear to be related with oviposition sites and environments where embryos and larvae develop. Hypsiboas faber embryos, which develop in small nests outside water bodies exhibit the largest hatching gland, and large, densely ciliated, highly branched external gills, as a possible response to low oxygen environments. The large and persistent adhesive glands of H. curupi and H. sp. gr. pulchellus could be related to the development of embryos and larvae in small streams. Within the same intrageneric group, certain embryonic traits of H. pulchellus (e.g., tooth row formula 2/3, minute external gills, low body ciliation) appear to be paedomorphic regarding ancestral ontogenies, but the ecological/functional correlation (if any) of these features is uncertain.