Genus Serpula Linnaeus, 1767

Type-species. Serpula vermicularis Linnaeus, 1767, designated by Heppell 1963.

Diagnosis. (from ten Hove & Kupriyanova 2009). Tube white, pink, orange, or yellowish, opaque; (semi)circular to trapezoidal in cross-section, rarely polygonal; longitudinal keels, peristomes, a hyaline outer layer or granular overlay may be present. Operculum soft to cartilaginous, funnel shaped with crenulated edge (fused radii). Peduncle smooth, cylindrical, without wings; inserted just below and between first and second dorsal radiole on one side. In large specimens the insertion outside the normal radioles, seemingly the first radiole. Radioles arranged in semi-circles, up to 50 per lobe in larger species. Pseudoperculum and inter-radiolar membrane present. Branchial eyes may be present. Mouth palps present. Stylodes absent. Seven (rarely 9) thoracic segments. Collar trilobed. Tonguelets absent, though wart-like protuberances may be present at base of cleft between ventral and latero-dorsal collar lobes. Thoracic membranes long, forming ventral apron across anterior abdominal segments. Collar chaetae bayonet-shaped and limbate. Apomatus chaetae absent. Uncini saw-shaped, with approximately 5 teeth, anterior fang simple pointed. Thoracic triangular depression present. Abdominal chaetae flat trumpet-shaped with denticulate edge; uncini similar to thoracic ones, smaller, anteriorly saw-shaped but becoming rasp-shaped towards the pygidium, with up to 12 teeth in profile, up to 8 teeth in a row. Achaetous anterior abdominal zone absent. Posterior capillary chaetae present. Posterior glandular pad absent.

Remarks. A recent study by Kupriyanova et al. (2008) demonstrates that the traditional genus Serpula is most probably paraphyletic.