Hyalopomatus Marenzeller, 1878: 393.— Zibrowius 1969: 13.— Kupriyanova 1993 b: 146.— Ben-Eliahu & Fiege 1996: 13.— Kupriyanova & Jirkov 1997: 211.— Knight-Jones et al. 1997: 146.—ten Hove & Kupriyanova 2009: 50 –52.— Sanfilippo 2009: 151.—Kupriyanova et al. 2010: 58–59.— 2011: 56.
Cystopomatus Gravier, 1911: 149.
Hyalopomatopsis de Saint-Joseph, 1894: 261 [in part].
Type species: Hyalopomatus claparedii Marenzeller, 1878
Diagnosis (after Kupriyanova et al. 2010, emend.): Tube white, opaque, sometimes with external hyaline layer; (semi) circular or quadrangular with rounded edges in cross-section. Hyalopomatus variorugosus Ben- Eliahu & Fiege, 1996, characterised by tubes with minute flap-like structures, and H. biformis (Hartman, 1960), which tubes have a longitudinal keel, are exceptions on this general pattern. Tabulae may be present. Operculum globular, soft, without distinct endplate or consisting of proximal ampulla with slightly chitinized distal cap; conspicuous constriction between operculum and peduncle; sometimes operculum absent. Peduncle sometimes thin (same thickness as radioles), cylindrical, smooth, wings absent; inserted outside radiolar crown proper in front of 1 st dorsal radiole on either side or between base of 1 st and 2 nd radioles. Pseudoperculum absent. Up to 15 pairs of radioles, in pectinate arrangement. Inter-radiolar membrane absent. Radiolar eyes rarely present. Stylodes absent. Mouth palps present. Six thoracic chaetigerous segments, 5 of which uncinigerous. Collar trilobed, tonguelets between ventral and lateral collar parts absent. Thoracic membranes short, ending at 1 st or 2 nd chaetiger. Collar chaetae simple limbate capillaries and fin-and-blade, with or without gap between fin and blade. Apomatus chaetae absent. Thoracic uncini rasp-shaped with about 20 small teeth in profile view, up to nine teeth in a transverse row above flat or slightly gouged anterior peg, made of two or more rounded lobes with shallow incision(s) in between. Triangular depression absent. Abdominal chaetae ending in long narrow tip made of pointed teeth that at least partly arranged in two rows on anterior and mid-abdominal segments, long capillaries on posterior chaetigers. Abdominal uncini rasp-shaped, similar to thoracic ones, but their anterior peg with 3–6 flat rounded lobes. Achaetous anterior abdominal zone may be present. Posterior glandular pad absent.
Remarks. The genus Hyalopomatus currently contains 13 nominal species mainly from bathyal and abyssal depths (ten Hove & Kupriyanova 2009; Kupriyanova et al. 2011).