Spinitanaopsis Larsen, 2005: 258 –259 (new synonymy). Crurispina Larsen, 2003: 781.
Kudinova-Pasternak (1990) erected the genus Cristatotanais for her species C. longicheles Kudinova-Pasternak, 1990, from 1038 m depth in the mid South Atlantic. Larsen (2003; 2005), in describing Spinitanaopsis insolituchelia (Larsen, 2003), from a cold-seep in the Gulf of Mexico at 570 m depth, made no reference to this paper, nor did he compare his genus with Cristatotanais. However, we cannot find any significant difference in characters between them sufficient to distinguish them at a generic level. Larsen’s species thus becomes Cristatotanais insolituchelia (Larsen, 2003) comb. nov.
Neither Kudinova-Pasternak (1990) nor Larsen (2003; 2005) assigned their genera to a family, but Larsen & Wilson (2002) included Cristatotanais in their new family Colletteidae, wherein the attachment of the cheliped was more consistent with the Colletteidae rather than their concept of the Anarthruridae. Conversely, Błażewicz-Paszkowycz and Poore (2008) resolved Cristatotanais (and, separately, Crurispina) into the Anarthruridae. The genus has typical anarthrurid mouthparts, with a reduced mandible (although taking the reduction to an extreme), reduced endites on the maxilliped, thin setae on the maxilla, and a naked labrum. The genus also has a simple (not spinelike) setae on pereopods 1 to 3 in contrast to the more robust spines on pereopods 4 to 6, and a reduced uropod exopod.
Finally, with a four-articled antennule, a reduced (absent) mandibular molar, narrow maxilliped endites and fused uropod exopod, Cristatotanais accords with the familial diagnosis for the Anarthruridae given by Larsen (2005; see also Bird 2004) rather than his diagnosis of the Colletteidae.