The Unique Amphipoda and Tanaidacea (Crustacea: Peracarida) Associated With the Brown Algae Dictyota sp. From the Oceanic Trindade Island, Southwestern Atlantic, With Biogeographic and Phylogenetic Insights

Abstract

Oceanic islands are known by their unique evolutionary histories and high endemicity caused by isolation. This is the first survey on the biodiversity of Peracarida from Trindade Island, a volcanic island located about 1,160 km off the Brazilian coast, with the first reports of Tanaidacea from the island and the description of Synapseudes isis sp. nov. and three new species of Amphipoda (Ampithoe thaix sp. nov., Elasmopus gabrieli sp. nov., and Eusiroides lucai sp. nov.). The results of the phylogenetic analysis of Synapseudes based on morphological characters and its biogeography through the Bayesian Binary MCMC analysis (BBM) suggested an Indo-Pacific origin for the genus. Finally, the biodiversity of Trindade Island is compared to that of the Abrolhos Archipelago, the closest islands from the coast on the continental shelf, suggesting a high endemicity of Peracarida, corresponding to 44% of Amphipoda and 50% of Tanaidacea species in the island of Trindade.