Fauveliopsidae Hartman, 1971

Salazar-Vallejo, Sergio I., Zhadan, Anna E. & Rizzo, Alexandra E., 2019, Revision of Fauveliopsidae Hartman, 1971 (Annelida, Sedentaria), Zootaxa 4637 (1), pp. 1-67 : 7

Fauveliopsidae Hartman, 1971

Fauveliopsidae Hartman, 1971: 1411 .

Fauveliopsidae :.— Fauchald 1977: 117; Petersen 2000: 493; Zhadan & Salazar-Vallejo 2019: 313.

Type genus: Fauveliopsis McIntosh, 1922 .

Diagnosis. Body cylindrical, swollen medially or posteriorly. Anterior and often median segments well-defined, intersegmental grooves deep. Integument smooth, finely papillose or rugose, rarely papillose and rugose. Prostomium without palps, antennae or eyes. Peristomium fused to prostomium. Nuchal organs flat, ciliated surfaces. Parapodia biramous, poorly developed, more prominent towards body ends. Chaetae all simple, capillaries and aciculars, variously falcate, in both rami. Pygidium terminal, anus protrusible. Genital papillae, if present, single or paired between some anterior chaetigers. Living inside gastropod or scaphopod shells, foraminiferan tests, or in flexible tubes with or without foreign particles.

Composition. There are currently two genera in the family: Fauveliopsis McIntosh, 1922 , with 16 species, and Laubieriopsis Petersen, 2000 with four species. These genera differ in body shape and integument, being expanded medially and posteriorly in Fauveliopsis , and cylindrical in Laubieriopsis . The integument is opaque and variously rugose or papillate in the former, or transparent and smooth in the latter. The chaetae are typically directed forward in the whole body of Fauveliopsis species, while in Laubieriopsis species only the first few chaetigers have anteriorly directed chaetae. The number of chaetigers and their relative length also differ between the members of these genera; thus, in Fauveliopsis their number and relative length varies throughout the body, while Laubieriopsis species have a relatively fixed number of chaetigers when adults, and their length is much less variable throughout body.

However, a different body pattern can be distinguished. Here, the body is very long, with many chaetigers, a smooth integument, and both body ends are swollen with the posterior region more markedly so. For this body pattern, we are herein proposing a new genus group name, Riseriopsis n. gen.

We do not include Mucibregma in Fauveliopsidae because we regard it as different. With some hesitation Kudenov (1985) regarded Mucibregma Fauchald & Hancock, 1981 as a fauveliopsid. It was originally included in Scalibregmatidae Malmgren, 1867 after the study of a damaged anterior fragment with a massive glandular area on peristomium. Because of its body structures, Fauchald & Hancock (1981:20) regarded it as belonging to a separate group in the classification proposed by Kudenov & Blake (1978). Kudenov (1985:339) regarded it as resembling fauveliopsids by having aciculars and capillaries and by lacking furcate chaetae; however, Kudenov noted that Mucibregma differs from fauveliopsids by having a well-defined prostomium, and by lacking interramal papillae, and concluded that it would “need to be assigned to a separate family.”