Integrative taxonomy supports the establishment of a new deep-sea family of Tanaidacea (Peracarida)

The tanaidacean family Colletteidae is large and exhibits highly diverse morphologies. A significant structural feature, the cephalothorax-cheliped attachment, is one of the sources of this variation but is still poorly understood or resolved in phylogenetic terms. The presence (and wide intrafamily disparities) of a lateral carapacial sclerite associated with this articulation is the main contributor to the diversity and this is investigated by us and shown to have valuable information for paratanaoidean phylogenies. We used integrative taxonomy to evaluate the status of several described colletteid genera, Caudalonga, Macrinella and Pseudoarthrura, based on analysis of COI and 18S genes, comparison with molecular data from ten other paratanaoidean families and detailed morphological study including confocal imaging of whole specimens, with the ‘sclerite’ a prime target for analysis. The results supported the establishment of a new family, Caudalongidae fam. nov., extracted from the overburdened Colletteidae, the narrow-bodied taxa defined principally by the small cheliped sclerite partly covered by a wide membrane and a short one-articled uropodal exopod. Apart from redescriptions/redefinitions of the genera Caudalonga, Macrinella, and Pseudoarthrura, two new genera Facultatotanais gen. nov. and Universitatotanais gen. nov. are erected and six new species are described, Caudalonga kurilensis sp. nov., F. bios sp. nov., U. freie sp. nov., U. gandavensis sp. nov., U. harvardi sp. nov., and U. jagiellonensis sp. nov. The Clarion Clipperton-Fracture Zone appears to support a high diversity of the family.