Bathychloeiasibogae Horst, 1910.

(modified from Böggemann (2009)). Body small, fusiform. Prostomium divided into an anterior and posterior lobe, with a median antenna on posterior lobe; paired lateral antennae and palps on anterior lobe. Eyes present or absent. Caruncle with well-developed folds and crenulations. Branchiae bipinnate from chaetiger 5 or 6, where enlarged. Dorsal, lateral and ventral cirri cirriform. Chaetae bifurcate. Pygidial cirri paired, cirriform to digitiform.

As the name Bathychloeia suggests, this genus was established for deep-water representatives similar to forms in predominantly shallow water genus Chloeia Lamarck, 1818. Chloeia was established by Lamarck (1818) to accommodate Chloeiaflava described from the Indian Ocean by Pallas in 1766 and currently contains 20 species occurring in the Indian, Pacific, and Atlantic oceans (Hartman 1959; Barroso and Paiva 2011). This genus is morphologically characterised by fusiform body shape and bipinnate branchiae. However, such characteristics are also shared with the rare, uniquely deep-sea genera Bathychloeia Horst, 1910 and Chloenopsis Fauchald, 1977. Bathychloeia has been distinguished from Chloeia by Horst (1910, 1912) mainly due to the presence of enlarged branchiae on chaetiger 5 (the first branchial chaetiger). This genus currently contains two deep-sea species, type species B.sibogae Horst, 1910 described from Malay Archipelago, depth of 1100 m and B.balloniformis Böggemann, 2009 described from the abyssal Atlantic. Similarly, Chloenopsis Fauchald, 1977 has been established to accommodate species originally described by McIntosh (885) as Chloeneaatlantica from the Canary Islands, depth ca. 2800 m. The validity of these genera and their separation from Chloeia has never been phylogenetically tested, but has been previously questioned (Böggemann 2009).