New Macrostylidae (Isopoda) from the Northwest Pacific Basin described by means of integrative taxonomy with reference to geographical barriers in the abyss

摘要

During the KuramBio expedition in 2012, previously unknown Macrostylidae (Crustacea, Isopoda) were collected from the Northwest Pacific Basin near the Kuril-Kamchatka Trench. Three of these species are described herein, Macrostylis amaliae sp. nov., M. daniae sp. nov. and M. sabinae sp. nov., using a combination of morphological and molecular-genetic approaches. The use of confocal laser scanning microscopy was evaluated and found to be a valuable, non-destructive method to visualize precious type material, as opposed to scanning electron microscopy, which renders material useless for other purposes. In the KuramBio samples two species of Macrostylidae (M. sabinae sp. nov., M. amaliae sp. nov.) dominated. Moreover, their females are morphologically indistinguishable and have thus been delineated by means of DNA data. The adult males, however, are distinguishable by their antennula and the type of aesthetascs. This is the first time that a new type of aesthetasc has been assigned to this family. For these two species evidence for sexual size dimorphism, in which the females are significantly larger than the males, was found. Macrostylis sabinae sp. nov. was widely distributed, so a biogeographical approach was followed and the dispersibility of benthic infaunal isopods across deep-sea trenches in the abyssal deep sea is discussed.