The Filter Apparatus of Larval Pelodytes punctatus (Amphibia: Anura)

Abstract

AbstractParts of the larval filter apparatus (ventral velum, branchial food traps, filter plates) were studied, using scanning electron microscopy. The primary species studied was Pelodytes punctatus, but Alytes obstetricans, Pelobates cultripes, Scaphiopus holbrooki, Telmatobius culeus, Hyla cinerea and Rana sphenocephala were also examined. Other data were taken from literature. Previous authors, in similar studies, maintained that variations in larval filter apparatus morphology supported the anuran suborders Archeo- and Neobatrachia. The present study concludes that the larval filter apparatus cannot be used to support any subordinal arrangement, but affirms its potential value at lower systematic levels. Pelobatoids tend to have modified filter apparatuses. Four types are recognizeable: 1) Pelodytes; 2) Scaphiopus; 3) Megophrys; 4)Pelobates, Leptobrachium, Oreolalax. Although other beaked Asian genera remain unstudied, these groups are enough to indicate that current pelobatoid systematics is erroneous. Pelodytes has the most primitive pelobatoid filter apparatus. This, the moderately derived larval chondrocranium and the peculiar mixture of certain primitive and derived character states in the adult frog (none shared with other pelobatoids), indicate a long independent phylogeny for Pelodytes. This in turn, supports recognition of a separate monogeneric family Pelodytidae.