Understanding the diversity and phylogenetic placements of New Zealand amphipods within a global context

Abstract

ABSTRACT Amphipods are an ecologically diverse group of crustaceans. Due to the limited number of fossil data and common morphological homoplasy, molecular data can be very useful to understand their evolutionary relationships and history. However, despite their global distribution and an increasing number of phylogenetic studies, molecular data from the Southern Hemisphere is considerably limited. Here, I report multigene data (18S, 28S, and COI) of New Zealand endemic freshwater families as well as some other marine taxa. Also, I report two new species/genera that have not been described yet. Phylogenetic analyses were conducted including major amphipod groups to understand phylogenetic placements of New Zealand amphipods. Based on the ML and Bayesian trees, Paracallipe, Paraleptamphopus, and the two unknown species belong to the eusiroids/iphimedioids clade; Parorchestia and a talitrid species clearly belong to talitroids; Paracorophium and Monocorophium were placed within corophiids; Themisto belongs to physosomatans; Josephosella was closely related to other hadzoids. The present study suggests that the Southern and Northern Hemisphere freshwater amphipods are likely to have originated from different marine ancestors. Molecular data from other regions in the Southern Hemisphere will be highly valuable for understanding the phylogeographic histories of amphipods that have shaped the current diversity and distribution.