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

normal radiole and maximally covering base of first three radioles. Pseudoperculum absent. Radioles arranged
in semi-circles, up to 24 per lobe; inter-radiolar membrane, branchial eyes, and stylodes absent. Mouth palps
present. 6 thoracic chaetigerous segments. Collar tri- to penta-lobed, collar edge may be almost laciniate;
tonguelets between ventral and lateral collar lobes present. Thoracic membranes long, forming ventral apron
across anterior abdominal segment. Collar chaetae absent; collar region with girdle of reddish ocelli.
Apomatus chaetae absent. All uncini sub-rectangular, rasp-shaped with > 20 teeth in profile, and up to 8 small
teeth in a row; anterior peg wide, flat, bluntly truncate, almost rectangular (Fig. 34A). Thoracic triangular
depression absent. Abdominal chaetae truly trumpet, with distal hollow triangular blade, abruptly bent (Fig.
34C). Achaetous anterior abdominal zone present. Long posterior capillary chaetae may be present. Posterior
glandular pad absent.
Remarks. Placostegus is one of three serpulid genera (see also Neomicrorbis and Vitreotubus) with an
entirely vitreous tube; completely transparent, glass-like in live animals, it may become milky-white semitransparent
after preservation in formalin. The tube in P. incomptus shows a remarkable dual appearance,
proximally with closely set transverse ribs, distally smoothly triangular. Fauvel (1927 fig. 128i) and Imajima
(1978 fig. 9c) mention a chitinous talon projecting from the endplate into the opercular bulb.
Placostegus has one evident diagnostic autapomorphy—the belt of bright red ocelli in the region where in
other genera collar-chaetae are found (e.g., Langerhans 1884 fig. 38b, Ehlers 1887 fig. 3, Hartman 1969 fig. 2;
our Fig. 1F).
1. Placostegus assimilis McIntosh, 1885, off Bermudas; bathyal
2. Placostegus californicus Hartman, 1969, Southern California
3. Placostegus crystallinus (Scacchi, 1836) sensu Zibrowius, 1968a, Eastern North Atlantic, Mediterranean;
?Red Sea, Indian Ocean, these reports might belong to a different species (Ben-Eliahu, pers. comm.)
4. ? Placostegus grayi Baird, 1865, no location given; generic status uncertain
5. Placostegus incomptus Ehlers, 1887, off Cuba; bathyal
6. Placostegus langerhansi Marenzeller, 1893, Madeira, Canary Islands
7. Placostegus tridentatus (Fabricius, 1780), Atlantic, Mediterranean, Indo-West Pacific.
30. Pomatoceros Philippi, 1844
(Fig. 35)
Type-species: Serpula triquetra Linnaeus, 1758
Number of species: 5
Tube generally white, opaque, though blue, purplish and pink parts may occur; usually with longitudinal
keel(s), may be with more or less regular series of pits, triangular or sub-triangular in cross-section; granular
overlay absent. Operculum with inverse conical to rather shallow ampulla, with calcified endplate, sometimes
bearing spines. Peduncle thick, triangular in cross-section, with distal lateral wings; a constriction between
peduncle and ampulla may be present; peduncle inserted almost medio-dorsally, covering the base of up to
three dorsal radioles. Pseudoperculum absent. Radioles arranged in semi-circles and up to 20 per lobe.
Branchial eyes and stylodes absent. Mouth palps present. 7 thoracic chaetigerous segments. Collar trilobed;
tonguelets between ventral and lateral collar lobes present. Thoracic membranes long, forming ventral apron
across anterior abdominal segment. Collar chaetae small, limbate. Apomatus chaetae absent. All uncini sawshaped
with 10–11 teeth, anterior peg blunt gouged (Fig. 35A, B). Thoracic triangular depression present.
Abdominal chaetae true trumpet-shaped, abruptly bent, distally with two rows of denticles separated by
hollow groove (Fig. 35C, D). Achaetous anterior abdominal zone absent. Long posterior capillary chaetae
absent. Posterior glandular pad absent.
Remarks. See remarks for Spirobranchus.
TAXONOMY OF SERPULIDS: STATE OF AFFAIRS
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