The discovery of a new amphinomid species from wood falls deployed near cold seeps (1694 m) at the Nile Deep-sea Fan (Mediterranean Sea) highlights the need to revise Amphinomidae to better characterize amphinomid diversity. The phylogenetic affinities of the new amphinomid and 12 other species from nine Amphinomida genera were inferred using data from two nuclear (18S rDNA and 28S rDNA) and two mitochondrial (COI and 16S rDNA) genes. The phylogenetic analyses indicated a close relationship of the new species with other amphinomids associated with temporary pelagic substrata, including
Amphinome sensu stricto (emended herein) and
Hipponoa. The new species belongs to a distinct lineage and we, here, erect a new genus to accommodate it.
Cryptonome gen. n. is the second amphinomid genus established for species from chemosynthetic environments.
Cryptonome conclava sp. n. is distinguished morphologically from all previously described rectilinear Amphinomidae by lacking notochaetal hooks, having a reduced caruncle, modified neurochaetae and branchiae on nearly all segments. Taxonomic issues regarding amphinomid species presently assigned to
Amphinome and the erroneous placement of related xylophylic taxa in
Eurythoe are also outlined. We emend and restrict the five known oceanic flotsam species with stalked heart-shaped caruncles to
Amphinome sensu stricto. An additional 15 species previously assigned to
Amphinome may belong to other genera (e. g.
Linopherus) and are here tentatively considered incertae sedis. Finally,
Eurythoe turcica and
Eurythoe parvecarunculata are transferred to
Cryptonome gen. n. as new combinations. A revised key to a subset of rectilinear amphinomid genera (relevant to this study) is presented.
