Bradabyssa Hartman, 1967

Salazar-Vallejo, Sergio I., 2017, Revision of Brada Stimpson, 1853, and Bradabyssa Hartman, 1967 (Annelida, Flabelligeridae), Zootaxa 4343 (1), pp. 1-98 : 20-21

Bradabyssa Hartman, 1967 emended

Bradabyssa Hartman, 1967: 122 .— Fauchald 1977: 116.

Brada.— Day 1967: 656 (partim).— Fauchald 1977: 116 (partim).

Type species. Bradabyssa papillata Hartman, 1967 , by original designation.

Diagnosis emended. Body fusiform, sometimes cylindrical with swollen ends. Cephalic cage chaetae often abundant, delicate. Body papillae abundant, at least dorsally, papillae tiny to very large, sometimes forming large transverse ridges. Notochaetae multiarticulate, at least distally, few, delicate. Neurochaetae aristate, rarely expanded subdistally. Branchiae usually abundant, thin cirriform filaments, sessile on branchial plate, separated into two lateral groups.

Remarks. Most species in Bradabyssa have multiarticulate notochaetae. However, two abyssal species, newly described below, have completely articulate notochaetae restricted to chaetiger 1; in chaetiger 2 notochaetae have their two distal thirds articulate, and by median chaetigers, the articulate region decreases to about the distal third of chaetae.

There appears to be a dichotomy present in protective features such as the tunic and papillae. Two different trends have been observed: some species possess many fine papillae to which fine sediment particles adhere, but others have fewer and larger papillae to which larger sediment particles attach. Even greater protection is afforded in some species by a thicker tunic to which sediment particles adhere directly, and not onto the papillae at all.

The species in Bradabyssa may be separated into four major morphological patterns by using the relative development of the tunic and papillae. These groups and their included species are as follows:

Group “ crustosa " contains those species whose members have a homogeneous cover with sediment particles embedded in the tunic, such that individual papillae are not detected, unless this cortex is removed. The species included are B. indica n. sp., B. mexicana n. sp., B. minuta ( Amoureux, 1986) , and B. sachalina (Annenkova- Chlopina, 1922) n. comb.

Group “ nuda ” includes all species whose bodies are provided with tiny, often abundant papillae, which may be eroded giving the body a naked appearance. The species included are B. alaskensis n. sp., B. antarctica ( Hartman, 1978) n. comb., B. bransfieldia ( Hartman, 1965) n. comb., B. nuda ( Annenkova-Chlopina, 1922) n. comb., B. rugosa ( Hansen, 1880) n. comb., and B. strelzovi (Jirkov & Filippova in Jirkov, 2001) n. comb.

Group “ verrucosa ” contains those species whose bodies have large tubercles or verrucae, which might have distal, fragile papillae; these tubercles are often relatively larger in posterior chaetigers. Verrucae can be of similar size, or being of at least two distinct sizes; the larger papillae may be basally enlarged generating rounded tubercles. The species included are B.abyssalis ( Fauchald, 1972) n. comb., B. annenkovae ( Buzhinskaja, 2001) n. comb., B. elinae n. sp., B. irenaia ( Chamberlin, 1919) n. comb., B. levensteinae n. sp., B. mammillata (Grube, 1877) n. comb., B. ochotensis ( Annenkova-Chlopina, 1922) n. comb., B. papillata Hartman, 1967 , B. tenebricosa (Berkeley, 1968) n. comb., n. status, and B. verrucosa ( Chamberlin, 1919) n. comb.

Group “ villosa ” includes those species whose bodies are provided with thin, long papillae, of similar size along the body, or becoming slightly larger laterally. The species included are B. capensis ( Day, 1961) n. comb., n. status, B. harrisae n. sp., B. hartmanae n. sp., B. ilyvestis ( Hartman, 1960) n. comb., B. intoshi ( Caullery, 1944) n. comb., B. jirkovi n. sp., B. kirkegaardi n. sp., B. monnioti n. sp., B. parthenopeia (Lo Bianco, 1893) n. comb., B. pilosa ( Moore, 1906) n. comb., B. pluribranchiata ( Moore, 1923) n. comb., B. setosa ( Verrill, 1873) n. comb., B. mezianei n. sp., B. tzetlini (Jirkov & Filippova in Jirkov, 2001) n. comb., B. villosa ( Rathke, 1843) n. comb., and B. whiteavesi ( McIntosh, 1885) n. comb.

Five species are included in Bradabyssa with some hesitation: B. hartmanae , B. ilyvestis , B. kirkegaardi , B. monnioti , and B. mezianei ; they were all found in deep-water sediments and their notochaetae have either distal articles with alternating lengths - several short ones followed by a longer one - or long articles with many short rings per article ( B. hartmanae ). These patterns are not found in other species in the genus or in the family. Three of these species have been considered as distinct on the basis of single specimens or of posterior fragments ( B. ilyvestis ); anterior end details are provided for B. hartmanae and B. mezianei which both have only 8 branchial filaments. These filaments, however, are not arranged in a continuous posterior row, as is the case in Brada or Pherusa, but are clearly separated into two lateral groups, which is regarded as an extreme reduction in the usual pattern for the genus. In both of the latter cases the specimens were in poor condition. They are included herein in Bradabyssa pending better material to clarify their affinities.