In functional ecology, morphology is expected to reflect function; however, occasional decoupling of these two can be found. In the case of feeding ecology, the diversity of the diet or diversity of the feeding modes within a clade is expected to be positively related to the diversity of the morphological traits involved in the feeding performance. Parrotfishes are separated into two main groups, the “reef” clade and the “seagrass” clade. Both groups have important differences in their evolutionary history. Still, more interestingly, they have important morphological and ecological differences. The genera Scarus and Sparisoma are the most specious genera of parrotfishes. They belong to each of those main groups, respectively. All Scarus species have the same feeding mode, while in Sparisoma, there are three different feeding modes. We want to test if the morphological jaw diversity of these genera corresponds with the diversity in their feeding modes. Using a disparity analysis of feeding traits within a phylogenetical framework, we did not find a relationship between functional feeding morphology and feeding modes of the American parrotfishes of the genera Scarus and Sparisoma. Interestingly we found that some muscular traits are the source of the high disparity in the genus Scarus. We explore some possible morpho-functional reasons for this phenomenon and reappraise the parrotfishes’ scraper feeding mode’s functional diversity. We also consider that there could be more ecological differentiation between Scarus species that we are aware of. Using an ancestral reconstruction of feeding modes of 52 species of parrotfishes, we found that the scraping feeding mode exhibited by all Scarus species is an evolutionary convergence with the scraping feeding modes performed by some Sparisoma species. Different selective pressures or ecological conditions may have shaped the differences in the feeding ecology and the feeding morphology of these two genera. Probably, key novel structures and muscular properties found in the Scarus species’ jaw played an essential role in this genus’s morpho-functional diversification. Finally, we propose that feeding modes may not fully capture the complexity of feeding ecology in parrotfishes.
A new species of sparid fish, Acanthopagrus oconnorae, is described based on 11 specimens collected in the shallow (0–1 m depth) mangrove‐adjacent sandflats of Thuwal, Saudi Arabia. The new species is distinguished from its congeners by the following combination of characters: second anal‐fin spine 12.8%–16.6% of standard length (SL); 3½ scale rows between the fifth dorsal‐fin spine and lateral line; suborbital width 5.7%–6.7% of SL; eyes positioned at the anterior edge of the head, often forming a weakly convex break in an otherwise gently curved head profile, when viewed laterally; caudal fin light yellow with black posterior margin (approximately half of fin); anal fin dusky grey, with posterior one‐fifth of the fin light yellow; black streaks on inter‐radial membranes of anal fin absent. The most similar species to A. oconnorae is Acanthopagrus vagus, which differs by the presence of a w‐shaped anterior edge of the scaled predorsal area, a more acute snout and black streaks on the inter‐radial membranes of the anal fin. Phylogenetic placement and species delimitation of A. oconnorae are discussed based on COI, CytB and 16S sequences. It is hypothesized that ecology and behaviour explain how this species avoided detection despite its likely occurrence in coastal areas of the Red Sea with historically high fishing pressure.
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