Comparative ontogeny of the oral disc in Physalaemus tadpoles - Anura, Leiuperidae

VERA CANDIOTI, MF; ALTIG, R; HAAD, B; BALDO, D; KOLENC, F; BORTEIRO, C

Congreso; IX International Congress of Vertebrate Morphology; 2010

The genus Physalaemus includes 42 species distributed from northern and central Argentina to northern South America. Tadpoles in this genus have one of five general oral configurations, distinguished by the number of lower labial rows and the arrangement of marginal papillae in the lower lip: C1) two lower labial rows and papillar margin complete; C2) two lower labial rows and papillar margin with ventrolateral gaps; C3) three lower labial rows and papillar margin with ventrolateral and ventral gaps; C4) three lower labial rows and papillar margin with ventral gap; and C5) three lower labial rows and papillar margin complete. We studied the development of the oral disc in seven species representing the five mentioned configurations, by analyzing ontogenetic series from the opening of the stomodeum (around Gosner stage 21) to the complete formation of the oral disc (around Gosner stage 26). The conservative developmental pattern of the earlier stages (appearance of the jaw sheaths, the two upper labial rows, two lower rows, and commissural papillae) with a later divergence of the ontogenetic trajectories, allows us to hypothesize that the evolution of the oral disc in several Physalaemus species involved the retention of some characters typical of earlier stages of basal ontogenies, as well as the appearance of new ones.