Hyalopomatus Marenzeller, 1878

Kupriyanova, Elena K., Nishi, Eijiroh, Kawato, Masaru & Fujiwara, Yoshihiro, 2010, New records of Serpulidae (Annelida, Polychaeta) from hydrothermal vents of North Fiji, Pacific Ocean, Zootaxa 2389 (1), pp. 57-68 : 58-59

Genus Hyalopomatus Marenzeller, 1878

Type-species: Hyalopomatus claparedii Marenzeller, 1878

Generic diagnosis (modified from ten Hove & Kupriyanova 2009: 50). Tube white, opaque, sometimes with external hyaline layer, but granular overlay absent; (semi) circular in cross-section. Exceptionally for this genus, Hyalopomatus variorugosus Ben-Eliahu & Fiege 1996 is characterized by tubes with minute flap like structures, and Hyalopomatus biformis has a longitudinal ridge ( Bastida-Zavala 2008). Tabulae may be present. Operculum globular, soft, without distinct endplate or consisting of proximal ampulla with slightly chitinized distal cap; well separated from peduncle by constriction; sometimes operculum absent. Peduncle very thin, cylindrical, smooth, without wings; inserted outside branchial crown proper in front of first dorsal radiole on one side or between base of first and second radiole. Pseudoperculum absent. Arrangement of radioles short pectinate, up to 15 pairs of radioles. Inter-radiolar membrane absent. Branchial eyes rarely present. Stylodes absent. Mouth palps present. 6 thoracic chaetigerous segments. Collar trilobed, tonguelets absent. Thoracic membranes short, ending at first or second thoracic chaetiger. Collar chaetae fin-and-blade, with or without gap between fin and blade and thus with uniform distal denticulate wing, and limbate blade. Apomatus chaetae absent. Thoracic uncini rasp-shaped with numerous small teeth, approximately 20 in profile, up to 9 teeth in a row above peg; anterior peg made of two or more rounded lobes with a shallow incision(s) in between, flat or slightly gouged in the middle. Triangular depression absent. Abdominal chaetae almost capillary ending in a long narrow tip made of pointed teeth that may be partly arranged in two rows; 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 capillary chaetae present. Posterior glandular pad absent.

Remarks. The composition and previous records of the genus were briefly summarized by ten Hove & Kupriyanova (2009). They list 12 morphologically similar species known mainly from bathyal and abyssal depths. Most recently Sanfilippo (2009) described another species, H. madreporae based on empty tubes only and commented on some congeners.

The SEM micrographs of abdominal chaetae in H. mironovi suggest two rows of pointed teeth at least at the base of the chaetal tip. This is a serious difference from the diagnosis given by ten Hove & Kupriyanova (2009) who state that abdominal chaetae in Hyalopomatus are “almost capillary with only tip flat narrow geniculate with pointed teeth”. Therefore, the generic diagnosis of ten Hove & Kupriyanova (2009) has been emended here.