Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America Author Blake, James A. text Zootaxa 2017 4218 1 1 145 journal article 37318 10.5281/zenodo.245827 69cf893c-7b35-48e8-ad78-d9775626f287 1175-5326 245827 9345C596-8656-4B5C-AD8C-2FACF4E9240C Genus Califia Hartman, 1957 Emended Type-species: Califia calida Hartman, 1957 , by original designation. Diagnosis. Prostomium pointed on anterior margin. Peristomium consisting of a single achaetous ring. Transition from thorax to abdomen abrupt due to distinct change in neuropodia. Branchiae from setiger 8–10; each branchia simple, lanceolate, may be lacking in most of abdominal region. Setigers 1–3 with dense fascicles of thickened uncini in neuropodia and 0 to few capillaries; 0 to few similar spines or uncini present in subsequent thoracic setigers, but capillaries numerous; neuropodial uncini with shafts either smooth or with ribs; tip of shaft with distinct sheath, often frayed, appearing bristled in light microscopy. Neuropodia with or without postsetal lobe; subpodial lobes absent. Abdominal segments lacking interramal and ventral cirri. Abdominal setae including capillaries, furcate setae, and flail setae; no uncini. Nature of pygidium unknown. Remarks. Califia is characterized by having heavy spines or uncini in anterior thoracic neuropodia, with setigers 1–3 appearing visibly different from other thoracic segments. Pettibone (1957) noted that modified setae were sometimes present among the capillaries of the unmodified setiger 4 of C. schmitti ( Pettibone, 1957 ) . This same feature has been observed on setigers 4–5 of the holotype of C. chilensis Hartman, 1967 ; C. bilamellata n. sp. has some neuropodial uncini on all thoracic setigers (see below). Califia is closely related to the genus Uncorbinia described by Hartmann-Schröder (1979) from Western Australia . Uncorbinia also has thickened neuropodial spines limited to the anterior segments of the thorax. In Califia , these anterior modified segments are biramous, with the notopodia bearing large fascicles of capillaries. In Uncorbinia , segments 1–4 are uniramous with notopodia entirely lacking. Furthermore, the uncini of Califia appear hooded on their tips due to a distinct sheath that upon wear appears bristled due to frayed fibrils, whereas the heavy spines of setigers 1–4 of Uncorbinia are either simple uncini or subuluncini. Uncorbinia has a few serrated uncini among the capillaries on the biramous setiger 5. Four Califia species are presently known from slope depths, one new species described here is from continental shelf depths.