Shallow-water northern hemisphere Jaera (Crustacea, Isopoda, Janiridae) found on whale bones in the Southern Ocean deep sea: ecology and description of Jaera tyleri sp. nov

The skeleton of a natural whale fall discovered in the Southern Ocean at 1,445 m was densely covered by one small, janirid isopod. Jaera tyleri sp. nov. is the first of its genus found in the southern hemisphere and in the deep sea and is described herein. Morphological and molecular investigations revealed the systematic position of this species new to science. Phylogenetic analysis of the 18S locus confirms that this species falls in a strongly supported monophyletic clade of Jaera species. The whale bone habitat of J. tyleri sp. nov. is quite different from those of other species of the genus Jaera. The analysis of bathymetric and distribution patterns of the Janiridae in general and Jaera specifically confirm the unusualness of the habitat for this isopod species. The abundance of J. tyleri sp. nov. on the whale bones and its absence from other nearby habitats suggests it to be a whale-fall specialist. The analysis of the size-frequency distributions of J. tyleri sp. nov. suggests multimodal population structure with continuous breeding activity throughout the year. The fecundity of the species is low but in line with reduced fecundity observed in polar and small-sized isopods.