Subfamily Microrbiniinae Blake, 2000

Type genus. Microrbinia Hartman, 1965 . Designated by Blake 2000.

Diagnosis. (Emended). Body small, separation of body into thoracic and abdominal regions weakly defined or lacking; parapodia lateral throughout, not shifted dorsally in abdominal segments. Branchiae present or absent. Prostomium broad, bluntly rounded or more elongate and conical or acute; nuchal organs present. Peristomium with 2–3 achaetous rings, separated from prostomium, sometimes only vaguely defined dorsally, laterally, or ventrally. Noto- and neuropodial postsetal lamellae with short postsetal lobes or absent. Bases of podia separated throughout; setal tori reduced. Setae consisting of capillaries always present, blunt-tipped spines or uncini and swan hooks present or absent; furcate setae typically absent. Pygidium with anal cirri present or absent.

Inclusive genera. Microrbinia, Orbiniella, Proscoloplos, and Pettibonella .

Remarks. Only species of Microrbinia and Orbiniella were identified in this study. Three species of Orbiniella are new to science. Species of Microrbiniinae are in part defined on negative characters.