Laminatubus ten Hove & Zibrowius, 1986

Rouse, Greg W. & Kupriyanova, Elena K., 2021, Laminatubus (Serpulidae, Annelida) from eastern Pacific hydrothermal vents and methane seeps, with description of two new species, Zootaxa 4915 (1), pp. 1-27 : 8-9

Laminatubus ten Hove & Zibrowius, 1986 (emended)

Type-species: Laminatubus alvini ten Hove & Zibrowius, 1986

Diagnosis. Tube white, with keel, granular overlay absent, hyaline outer layers may be present. Operculum globular, semitransparent or divided into proximal ampulla and distinct endplate made of thickened yellowish cuticle. Peduncle cylindrical, gradually merging into opercular ampulla, constriction absent; inserted to left side, proximal from first and second normal radiole. Pseudoperculum absent. Radioles not connected by inter-radiolar membrane, arranged into slightly ascending spiral of up to two whorls. Stylodes and radiolar eyes absent. Mouth palps absent. Six or seven thoracic chaetigerous segments. Collar with medio-ventral and two latero-dorsal lobes, continuous with thoracic membranes, forming apron. Tonguelets absent. Collar chaetae simple limbate or Spirobranchus - type and limbate. Apomatus chaetae absent.All uncini saw-shaped with 5–7 teeth, anterior fang simple pointed. Thoracic tori converging posteriorly, forming triangular depression. Abdominal chaetae long, with hollow trumpet-shaped tip. Posterior abdominal chaetae become longer, but posterior capillary chaetae absent. Achaetous anterior abdominal zone absent. Posterior glandular pad absent.

Remarks. Until now Laminatubus was monotypic and the diagnosis has been emended here to account for the presence of variable number (six or seven) thoracic chaetigerous segments as well as variability in the presence of Spirobranchus - type collar chaetae. This is to allow for features found in the two new species described here. Laminatubus was erected by ten Hove & Zibrowius (1986), who did not do any phylogenetic analysis and decided that, based on a unique combination of characters, L. alvini did not fit in with any existing genera at the time. A comparative table in ten Hove & Zibrowius (1986) included Laminatutus and 11 genera where L. alvini potentially belonged. Of these, Laminatubus alvini was most similar to Neovermilia as the two taxa share a chaetation pattern (including true trumpet-shaped abdominal chaetae, saw-shaped uncini with few teeth and pointed fangs, and lack of ‘ Apomatus chaetae’), a similar globular operculum, and a long thoracic membrane forming an apron. However, Neovermilia is problematic and unlikely to be monophyletic as was suggested by ten Hove & Kupriyanova (2009). It was established by Day (1961) for N. capensis , a single specimen without a tube dredged from 18 m off Cape Province, South Africa. According to Day (1961: page 551), the new taxon has “characters intermediate between Serpula and Vermiliopsis ”, the operculum “is borne on a slender triangular peduncle without wings, is radially symmetrical, soft and funnel-shaped”. Thus, while the table of ten Hove & Zibrowius (1986) listed the presence of peduncular ledges (= winglets) in Neovermilia as a character separating it from Laminatubus , based on Day (1967: fig. 38.6a), this feature is absent in N. sphaeropomata . While presence of seven thoracic chaetigers and lack of Spirobranchus - type special collar chaetae indicates the two new Laminatubus species belong with Neovermilia , these characters are somewhat labile. A broader phylogenetic analysis with denser taxon sampling is required to resolve the relationships and status of Laminatubus and Neovermilia and we presently regard Laminatubus as a valid taxon. It remains unclear whether species reported as Neovermilia n. sp. as identified by H. Zibrowius from Middle American Trench off Manzanillo in Mexico and cold seeps in Nankai prism of Peru Trench, Peruvian active margin and Terevaka intra-transform ridge off Easter Island, Chile (in Sibuet & Olu 1998) belong to Laminatubus .