Parasemnoderes intermedius gen. n., sp. n.—the First Abyssal Representative of the Family Semnoderidae (Kinorhyncha: Cyclorhagida)

Abstract

A new genus and new species of semnoderid kinorhynchs, Parasemnoderes intermedius gen. nov., sp. nov. collected from the abyssal plane at the south border of the Kuril-Kamchatka Trench at the depth 5348 m is described and illustrated using light and electron microscopy. This new representative of the family Semnoderidae is characterized by the structure of the first trunk segment consisting of externally closed cuticular ring with indistinct intracuticular tergosternal junctions. Cuticular ring of the first trunk segment is with deep and narrow middorsal incision and much broader midventral incision filled by midventral placid. Lateroventral spines aciculate, on trunk segments 3–9. Lateroventral accessory spines are minute, only on trunk segment 5. Laterodorsal spines on trunk segment 10. Parasemnoderes intermedius gen. nov, sp. nov. constitutes the third genus the Semnoderidae described so far (Semnoderes and Sphenoderes) and the first species of this family described from the abyssal depth. The total species number of the family Semnoderidae has been increased up to 6. A key to the species of the family Semnoderidae is proposed.