Genus Pyrgopolon de Montfort, 1808

Type species: Pyrgopolon mosae de Montfort, 1808 Synonyms: See Jäger (1993, p. 95) Sclerostyla Mørch, 1863

Hepteris Regenhardt, 1961

Material examined: BM (NH) 1971:230, Pyrgopolon ctenactis (Mørch), 1863 from Station 212, Santa Barbara, Bonaire, - collected and determined as Sclerostyla ctenactis Mørch, 1863, and donated to the NHM by ten Hove.

Description. Tube: Ten Hove (1973: 7–8) describes it as variable with regard to colour and longitudinal ridges. It is white to pinkish in colour, with usually three but may be four or more longitudinal ridges, all variations occurring in the same locality or even on the same tube.

Worm: As seen in the above material from Bonaire, operculum calcareous, inserted independently of branchial radioles of both sides (Fig. 3); funnel-shaped, smooth on the outside, scalloped along the rim, and with a toothed ridge corresponding to each scallop extending along the inside of the funnel (see also ten Hove, 1973, figs 25–29, 30–33, plates 3–4). Peduncle: solid, calcareous, continuous with the calcareous operculum; wingless. Interradiolar membranes present; thoracic membranes extend to end of thorax (Fig. 3); apron present (not shown in figure 3).

Chaetae: Collar chaetae may be absent; when present, special collar chaetae may possess a distally papillate shaft, and a papillate boss (see ten Hove, 1973: 2, figs. 2–4). Apomatus -chaetae: absent. Uncini: sawshaped, most anterior uncinal process simple. Abdominal neurochaetae: geniculate.

Remarks: The description of genus Pyrgopolon was originally based on the tube and operculum of its fossil type species Pyrgopolon mosae de Montfort, 1808 (see Jäger 1993, p. 95). However, as shown below, it is now possible to include characters of the worm itself, based on the type species of the extant genus Sclerostyla which has been synonymized with Pyrgopolon, namely, Sclerostyla ctenactis Mørch, 1863 (= Serpula (Sclerostyla) ctenactis Mørch, 1863). A similar situation was encountered recently with regard another fossil serpulid genus, namely, Spiraserpula Regenhardt, 1961, which was described on the basis of the tube of its fossil type species, S. spiraserpula Regenhardt, 1961. However, on the basis of 19 extant species of Spiraserpula described by Pillai & ten Hove (1994), it was possible to include also characters relating to the worm itself in its generic definition.

For a key to extant species of Pyrgopolon (as Sclerostyla) see ten Hove (1973: 5).

Distribution: including other extant species of Pyrgopolon. For descriptions and distribution of Pyrgopolon ctenactis (Mørch, 1863), P. d i f f e re n s (Augener, 1922) and P. semiannulata from the Caribbean (under the genus Sclerostyla) and their distribution, see ten Hove (1973) and Bastida-Zavala (2008: 42).