Zootaxa, Taxonomy of Serpulidae (Annelida ... - Magnolia Press

31. Pomatoleios Pixell, 1913
(Fig. 36)
Type-species: Pomatoleios crosslandi Pixell, 1913, junior synonym of Placostegus cariniferus var. kraussii Baird, 1865
Number of species: 1
Tube white or bluish, opaque, triangular in cross-section, with medial keel projecting into flap over the
entrance. Granular overlay absent. Operculum inverse conical with flat calcareous plate; sometimes with talon
projecting into opercular ampulla (best seen if operculum is cleared in glycerine). Peduncle thick, triangular in
cross-section, with distal wings, without constriction, inserted almost medially, slightly left, covering base of
up to five radioles. Pseudoperculum absent. Radioles arranged in semi-circles, up to 19 per lobe, connected by
very high inter-radiolar membrane. Branchial eyes present (single ocelli visible in fresh material only).
Stylodes absent. Mouth palps present. 6 thoracic chaetigerous segments (in juveniles 7). Collar with entire
edge, tonguelets between ventral and lateral collar lobes present; thoracic membranes forming ventral apron.
Collar chaetae absent (limbate ones present in juveniles only). Apomatus chaetae absent. Uncini saw-shaped
with fairly numerous (10–11) teeth, anterior peg wide and blunt, gouged (Fig. 36B). Triangular depression
present. Abdominal chaetae true trumpet-shaped, abruptly bent, distally with two rows of denticles separated
by a groove (Fig. 36A). Achaetous anterior abdominal zone absent. Posterior capillary chaetae and posterior
glandular pad absent.
FIGURE 36. SEM micrographs of chaetae in Pomatoleios kraussii. Madagascar, Tuléar, littoral, det. and don. H.
Zibrowius, legit J. Picard, ZMA V.Pol. 3068. A—anterior abdominal chaetae with hollow tips, B—thoracic uncini of 1 st
row.
Remarks. Opercular talons as reported by Pillai (1965 fig. 22H) and ten Hove (1973 fig. 43) are not
consistenly mentioned (nor looked for) in the literature. Whether or not the presence of such a talon is a
character distinguishing between populations or even taxa should be investigated.
Pomatoleios kraussii is widely distributed in the Indo-Pacific forming intertidal aggregations. The only
difference between Pomatoceros and Pomatoleios is the more or less consistent lack of collar chaetae in the
latter. However, collar chaetae may be present in juvenile specimens (Zibrowius 1968a, Crisp 1977, ten Hove
& Nishi 1996), and occasionally absent in Pomatoceros (e.g., 9 specimens from the Irish Sea, ZMA V.Pol.
3201) as well as in Spirobranchus (e.g., as Olga elegantissima Jones, 1962), thus this monotypic genus likely
TAXONOMY OF SERPULIDS: STATE OF AFFAIRS
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