A new species of <i>Echinoderes</i> (Kinorhyncha: Cyclorhagida: Echinoderidae) from the recently rediscovered detrital habitat of macerating Neptune grass ( <i>Posidonia oceanica</i> ) at Ischia Island (western Mediterranean Sea)

The Neptune grass (Posidonia oceanica) forms large, shallow, underwater meadows in the Mediterranean Sea that provide important ecosystem services. Although P. oceanica beds and onshore banquettes have been intensely studied, other habitats derived from this phanerogam have remained uncharted. This is the case of the offshore macerating P. oceanica detrital habitat, which has been recently rediscovered during a survey off Ischia Island (western Mediterranean Sea). The habitat originates from remains of leaves and rhizomes that end up on the seafloor mixed with the sediment due to oceanic currents. During a previous study that characterized the meiofaunal community living in the macerating P. oceanica detrital sediment, a large number of Kinorhyncha were found. An exhaustive analysis of the specimens revealed a new species of Echinoderes, the most diverse genus in the phylum. Echinoderes semprucciae sp. nov. is unique among its congeners by the combination of the following features: middorsal spines on segments 4, 6 and 8, lateroventral spines on segments 8–9, male laterodorsal tubes on segment 10, lateroventral tubes on segment 5, lateral accessory tubes on segment 9 and female ventromedial papillae on segment 6. The present study represents the first record of Kinorhyncha inhabiting a macerating P. oceanica detrital habitat and aims to significantly contribute to the taxonomy of the group in the Mediterranean Sea.http://zoobank.org/urn:lsid:zoobank.org:pub:571FFFC0-D0CB-443B-B6F2-A6EA3C2EF143