Pyrgopolon de Montfort, 1808

Ten Hove, Harry A. & Kupriyanova, Elena K., 2009, Taxonomy of Serpulidae (Annelida, Polychaeta): The state of affairs, Zootaxa 2036, pp. 1-126 : 86-88

37. Pyrgopolon de Montfort, 1808

( Fig. 42)

Type-species: Pyrgopolon mosae de Montfort, 1808 (a fossil taxon)

Number of (Recent) species: 3

Tube white or pinkish/red, opaque, generally with longitudinal ridges and/or transverse rims; tabulae may be present. Cross-section semi-circular to trapezoidal, erect part polygonal. A hyaline, granular overlay may be present. Operculum funnel-shaped, with numerous radial ridges on inner side; operculum and peduncle entirely calcified; with an extremely long calcareous talon embedded into the tissue of the peduncle that is inserted medially. Pseudoperculum absent. Radioles arranged in semi-circles, up to 38 per lobe, united by inter-radiolar membrane for 1/4–1/2 of their length, surrounding pair of well-developed mouth palps. Branchial eyes have not been observed but the brim of the skin around the operculum is scalloped, due to a circle of compound eyespots ( Fig. 6B). Stylodes absent. 7 thoracic chaetigerous segments, though collar chaetae generally missing. Collar with large, bilobed ventral part; tonguelets between lateral and ventral collar lobes present. Thoracic membranes very wide anteriorly, narrowing at 3 rd or 4 th segment, and united ventrally on first abdominal segment forming an apron. Collar chaetae (if present) Spirobranchus - type and limbate. Apomatus chaetae absent. Thoracic uncini saw-shaped, with 8–9 teeth, anterior peg bluntly truncated, indented anteriorly ( Fig. 42C). Thoracic tori almost touching ventrally in posterior thoracic segments of larger specimens, leaving a clear triangular depression. Abdominal chaetae almost capillary, with short hollow trumpet-shaped tips, smoothly bent and with double row of pointed teeth extending in long lateral spine ( Fig. 42D). Abdominal uncini rasp-shaped with 8–11 teeth in profile, 2–3 teeth in a row ( Fig. 42A, B). Achaetous anterior abdominal zone absent. Short capillary chaetae present posteriorly. Posterior glandular pad, if present, hardly visible.

Remarks. Sclerostyla Mörch, 1863 has been synonymized with Pyrgopolon , according to Jäger (1993, 2004) including the genera Hamulus and Turbinia , known only from the fossil record. This opinion is shared by Belokrys (1994). Fossils have been mentioned from the Maastrichtian (Cretaceous) from e.g., the Southern Netherlands, Northern Belgium, and the Crimean Mountains. The Recent distribution of the genus is the tropical seas of the Americas and is little known because the animals are difficult to find as their tubes are usually embedded into substrate. The distinguishing feature (autapomorphy) of the genus is the funnel-shaped calcareous operculum continuing into a calcareous peduncle (talon). Opercular talons, but shorter, are also known in Pomatoleios and Neomicrorbis . The bright red “glandular fields” around the brim of the operculum mentioned by ten Hove (1973 figs 32–33) in the meantime have been found to be compound eyespots (HAtH, SEM observations); ten Hove’s (1973) revision still remains the most comprehensive source of information about this genus.

1. Pyrgopolon ctenactis ( Mörch, 1863) , St. Thomas, Caribbean and tropical Pacific America

2. Pyrgopolon differens ( Augener, 1922) , Barbados, Shelf of Surinam

3. Pyrgopolon semiannulatum (ten Hove, 1973) , Barbados.