Tadpole types of Chinese megophryid frogs (Anura: Megophryidae) and implications for larval evolution

Abstract

Abstract The larval body shapes and oral discs of 30 frog species from the family Megophryidae from China were examined. Using a phylogenetic framework derived from a Bayesian analysis of published mitochondrial cytochrome b and 16S rRNA gene sequences, we deduced a pattern of historical change among megophryid larval forms. These larvae were categorized into four types according to their body shapes and oral discs: (A) Leptobrachiini type, (B) Lalax type, (C) Brachytarsophrys type, and (D) Megophryini type, of which B and C are novel types. Type A is characterized by a typical oral disc with multiple rows of teeth, representing the tadpole type of the most recent common ancestor of the family Megophryidae. Type B has a typical oral disc with reduced tooth rows, an elongated labium, and integumentary glands. Type C has no labial teeth and a smaller umbelliform oral disc. Type D is characterized by a lack of labial teeth, an enlarged umbelliform oral disc, representing the tadpole of the most recent common ancestor of the subfamily Megophryinae. Our analysis supports the hypothesis that the umbelliform oral disc is apomorphic and also reveals the close association between morphology and microhabitat.