Larval morphology of reed frogs, Hyperolius kivuensis and H. viridiflavus, from western Kenya (Amphibia, Hyperoliidae)

Abstract

We describe external characters, oral disc and oral cavity structures of larval Hyperolius kivuensis and H. viridiflavus, i.e. exotrophous lentic benthic type IV tadpoles. External morphology of both is comparable and matches descriptions of other Hyperolius species. Differences among the two taxa were noted in the keratinized labial teeth. In H. kivuensis, the spoon-shaped cusped tooth type is frequent and represented by two different subtypes: (i) "cusped" with four cusps, the two distal of which only slightly larger than the lateral cusps; (ii) "pointed" with the two distal cusps larger than the two lateral cusps forming a bifurcation. The latter subtype is rare in H. kivuensis, while most frequent in H. viridiflavus. In this species, also another type occurs, characterized by two long distal cusps, forming a bifurcation, and two small lateral cusps; the cusped type with cusps of the same size as in H. kivuensis is rare. Both species show similar oral cavity structures except for the choanae position, i.e. arranged in a V that is opened posteriorly in H. kivuensis versus a V opened anteriorly in H. viridiflavus. Choanae position and keratinized labial teeth structure may provide diagnostic features for these and other species of Hyperolius.