Ecomorphology and evolution of the pharyngeal apparatus of benthic damselfishes (Pomacentridae, subfamily Stegastinae)

Abstract

Coral and rocky reefs are productive and complex habitats that favor niche partitioning, the appearance of functional and morphological uniqueness in their inhabitants, and diversification. Members of the damselfish (Pomacentridae) subfamily Stegastinae, with 8 genera and 66 species, are among the most common inhabitants of reefs. Feeding behavior tends to be similar for most members of this subfamily, as they are benthic species that aggressively protects their feeding areas. Their main food sources are algae and invertebrates, but they also feed opportunistically on a wider range of resources. In this study, I analyzed the morphology of the pharyngeal jaw apparatus in an ecological and phylogenetic context to understand the role of these structures in promoting functional capacity and/or diversification. I found variation in the number and morphology of teeth, particularly in the lower pharyngeal jaw. The presence or absence of hard-shelled items in the diet appears to be a factor shaping the evolution of the pharyngeal jaw apparatus. Finally, the pharyngeal plates in the subfamily Stegastinae are highly diverse, reflecting specialization in processing particular prey items.