Molecular phylogeny of Salmoneus Holthuis, 1955 and its satellite genera (Decapoda: Caridea: Alpheidae) reveals hidden diversity and multiple instances of morphological and ecological convergence

Abstract

The present study deals with the intricate phylogenetic relationships within an important clade of the caridean shrimp family Alpheidae, which includes the genera Salmoneus, Deioneus, and Triacanthoneus. Using molecular data from four genes (16S, 18S, COI, and H3), we herein provide the most comprehensive phylogenetic hypothesis for this alpheid clade, with 161 terminals representing 117 ESUs, i.e. genetically distinct species. Our analysis reveals four well-supported larger Clades, as well as 25 smaller clades, corresponding to species groups or species complexes. The results also show that the symbiotic lifestyle evolved multiple times within this clade, in some instances promoting convergent evolution. Ancestral character state analysis unveils extreme plasticity and independent shifts in the minor cheliped types. Furthermore, the impact of different lifestyles on the evolution of each minor cheliped type is discussed. Finally, we address the resulting paraphyly of Salmoneus and the intergeneric relationships between Salmoneus, Deioneus and Triacanthoneus.