Description of two new species of Zosime (Copepoda: Harpacticoida: Zosimeidae), including remarks on its phylogeny and distribution on the Great Meteor Seamount plateau (North- east Atlantic Ocean)

摘要

Quantitative sampling during the POS397 GroMet expedition in 2010 allowed analysis of the community structure of Zosimeidae on the Great Meteor Seamount (GMS) plateau. Twelve species of Zosime Boeck, 1873 were identified; 11 were recorded in the middle, nine in the northern, and 10 in the southern region. Similarity and diversity analyses showed no differences in community structure between these regions. The community seemed unaffected by geographical features; similarities between regions could reflect the uniform sediment structure and the complex water current system. Zosime can be characterised as monophyletic, due to the apomorphic one-segmented endopod of the mandible, armed with at most four setae. Two new species are described. Zosime carsteni sp. nov. (incrassata group) is defined by blunt spinules on the outer spines of exopods 1-3 of pereiopods 2-4 and the spinose nature of the innermost distal element of endopod 3 of pereiopods 1-4. Zosime eliasi sp. nov. (typica group) is defined by a flexible outer seta on the maxillipedal endopod. As both species bear an eight-segmented antennule (most plesiomorphic condition known so far), the recently erected anneae group is included into the typica group. An updated key of Zosime at the species level is given.