Plesioscolecithrix (Copepoda, Calanoida, Scolecitrichidae): a new genus, and a new species from the high Antarctic Weddell Sea (Southern Ocean)
Both sexes of Plesioscolecithrix juhlae gen. et sp. nov. are described from the Weddell Sea shelf, Antarctic, in near-bottom water layers from 167 to 254 m. The new genus has segmentation and setation of the swimming legs P1-P4 typical of the Clausocalanoidea. With the group of clausocalanoidean fam...
| Summary: | Both sexes of Plesioscolecithrix juhlae gen. et sp. nov. are described from the Weddell Sea shelf, Antarctic, in near-bottom water layers from 167 to 254 m. The new genus has segmentation and setation of the swimming legs P1-P4 typical of the Clausocalanoidea. With the group of clausocalanoidean families Diaixidae Sars, 1902, Parkiidae Ferrari & Markhaseva, 1996, Phaennidae Sars, 1902, Tharybidae Sars, 1902 and Scolecitrichidae Giesbrecht, 1892 it shares the possession of sensory setae both on the maxilla exopod and on the syncoxa of the maxilliped. The genus is hypothesized to be one of the most primitive among the family Scolecitrichidae and deviations from the usual scolecitrichid morphology are discussed. Its family placement is tentative because of many significant morphological deviations from the scolecitrichid type. The main generic characters distinguishing the new genus from other scolecitrichids are as follows: the number (four) and morphology of thin brush-like sensory setae with very small brushes at the exopod of the maxilla; the simple structure of the male fifth legs (with almost symmetrical coxo- and basipods in both legs); well-developed oral parts in males; the absence of the female fifth legs. |
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