Xancithrix gen.n. (Copepoda: Calanoida), a new benthopelagic genus of Clausocalanoidea from deep Atlantic waters

摘要

A new benthopelagic genus and species Xancithrix ohmani (Clausocalanoidea) with sensory setae on maxilla and maxilliped is described from females and males from the abyss of the South Atlantic. A new genus is proposed as it is amongst the most primitive bradfordian genera retaining the ancestral bradfordian setal pattern of mouth parts: the maxilliped praecoxal endites of the syncoxa have a setal sequence of 1, 2, 3; the maxilla praecoxal endite and endopod with 5 and 9 setae respectively, and the maxillule praecoxal arthrite, coxal endite, proximal and distal basal endites, endopod, exopod and coxal epipodite has a setal sequence of 14, 5, 4, 5, 11, 10, and 9, respectively. This new genus is attributed to the Diaixidae and is distinct from all other diaixids in not having a rostrum, the maxilliped coxal endite with a small distal attenuation, and the P1 endopod lateral lobe bears a pore.