Larval anatomy of monotypic painted ant nest frogs Lithodytes lineatus reveals putative homoplasies with the Leptodactylus pentadactylus group (Anura: Leptodactylidae)

The morphological diversity of anuran larvae made them an important source of information for evolutionary and systematic studies. For the monotypic frog genus Lithodytes, which has an interesting taxonomic history, including its past synonymizing with Adenomera and its placement as a subgenus of Leptodactylus, the information provided from its larvae can help to understand its systematics interrelationships and also provide insights about its evolutionary trajectories. Herein, we provide a detailed description of the larval morphology of Lithodytes lineatus, including novel data of internal morphology (buccopharyngeal cavity and skeleton), and discuss some morphological and evolutionary aspects in relation to other members of the subfamily Leptodactylinae. Despite the overall similar larval morphology with others members of the subfamily, we identified four autapomorphic traits for Lithodytes and seven purported homoplastic traits with a subclade of the Leptodactylus pentadactylus species group that likely evolved convergently. Some of these traits have been previously associated with a carnivorous diet. Putative homoplastic and autapomorphic characters served as additional diagnostic traits for Lithodytes, supporting its recognition as a distinct genus within Leptodactylidae