Watersipora subtorquata (d’Orbigny, 1852), d'Orbigny, 1852

Ryland, John S., Blauwe, Hans De, Lord, Richard & Mackie, Joshua A., 2009, Recent discoveries of alien Watersipora (Bryozoa) in Western Europe, with redescriptions of species, Zootaxa 2093, pp. 43-59 : 55-56

Watersipora subtorquata (d’Orbigny, 1852)

( Figs 3 , 4 A, C, E, F)

Escharina torquata [Milne] Edwards: d’Orbigny 1842, pl. 4, fig. 3; 1847: 11.

Schizoporella atrofusca Busk : Hincks 1868: 269, pl. 10, figs 4–5.

Schizoporella aterrima Ortmann, 1890: 49 , pl. 3, fig. 36.

Lepralia ? cucullata: Waters 1909: 150 , pl. 15, figs 1, 5 [pars].

Watersipora cucullata: Hastings 1930: 729 [pars], pl. 15, figs 102–104 only.

Watersipora cucullata: Marcus 1937: 118 , pl. 24, fig. 63A, B.

Watersipora cucullata: Mawatari 1952: 14 , fig. 1 A–E (not 1F).

Watersipora cucullata var. watersi Mawatari, 1952: 16 , fig. 1G

[?] Dakaria subovoidea: Harmer 1957: 1022 , pl. 69, figs 11–13.

Watersipora subtorquata: Ryland 1974: 345 , fig. 3C.

“ Watersipora subovoidea ” fide Harmer: Soule & Soule 1976: 302, pl. 3, fig. 4; pl. 4, fig. 4.

Watersipora subtorquata: Soule & Soule 1976: 302 , pl. 2, fig. 3; pl. 3, fig. 3; Gordon 1989: 40, pl. 20, B–H); Seo 1999: 222, fig. 1; Taylor & Gordon 2002: 4, reproducing d’Orbigny’s original figures (fig. 1A, B) and giving an SEM of the holotype ( Fig. 1 C); Florence et al. 2007: 39, fig. 14I J.

Material examined. All specimens are in the Natural History Museum, London. Low Isles, Queensland, Australia (Great Barrier Reef), July 1972, JSR (2 slides: 1 intact, NHM 2007.12.14.9; 1 cleaned, NHM 2007.12.14.10) ( Ryland 1974); Bay of Arcachon, on shell (NHM 2007.12.14.11), HDeB, August 2003 (1 slide, decalcified, NHM 2007.12.14.12); St-Jacut-de-la-Mer, Brittany, France, HDeB, April 2005 (on oyster shell, NHM 2007.12.14.13; SEMs; 2 slides: 1 cleaned, NHM 2007.12.12.14; 1 decalcified, NHM 2007.12.14.15); St Peter Port harbour, Guernsey, Channel Islands, May 2007, RL (SEM; 3 slides: 1 intact, NHM 2007.12.14.16; 1 cleaned, NHM 2007.1.14.17; 1 decalcified, NHM 2007.12.14.18).

Description. Colonies encrusting, subcircular or with broad, spreading lobes, often overgrowing older layers; or erect with bilaminar lobes; sometimes with a broad and extensive orange-red cortical zone, paling and becoming greyish away from the edges; or dark sepia, black or deep purple with a narrow, orange growing margin (colours fade with drying). Zooids subrectangular or slightly hexagonal, sometimes narrower proximally (usually when associated with row division); large, distinct, about twice as long as wide, 750–1100 (mean ~950) × 300–600 (mean ~430) μm (globally), variable within and between colonies. Frontal skeletal wall rather flat, perforated by numerous large round pseudopores, 20–30 μm diameter; covered by a rather transparent layer with a shiny cuticle. Orifice large, oval, somewhat wider than long; 130–260 (mean ~230) μm; occupying>10% of the total zooid area; with a proximal sinus demarcated by condyles, ~55 × 115 μm; surrounding rim variably developed, sometimes in the form of paired mucrones beside the sinus, often crestlike distally; a pair of areolae proximolateral to the orifice, one each side, about the size of a pseudopore but containing a multiporous septulum. Condyles in the form of narrow shoulders distal to and slightly deeper than the angle of the orifice rim that separates anter from sinus. Operculum strongly pigmented, with a dark broad, biconcave band proximally, gradually spreading around paired clear areas. Polypides with orange lophophores 740–850 μm long, ~24 tentacles ( Gordon 1989).

Variation and remarks. The operculum, with the dark biconcave central band that spreads distally around a pair of subcircular lateral ‘windows’, is diagnostic but the details cannot be seen clearly without special preparation. In the orange colonies from Guernsey the dark band is narrow, about the width of the sinus at the waist ( Fig. 4 F); in the black colonies from St-Jacut and the Bay of Arcachon the dark band is noticeably broader, greater than the width of the sinus, and its lateral margins are more sharply defined ( Fig. 4 E).

Hincks (1886) named a variety labiosa from the Arabian Sea, with the orificial rim raised as mucrones on either side of the sinus, which appears referable to this species and the counterpart of W. subovoidea var. labiosa Calvet (see above). Ortmann’s (1890) Schizoporella aterrima , clearly belonging to Watersipora , is unrecognizable to species. It was included by Mawatari (1952) in the synonymy of W. cucullata but his account is clearly based on W. subtorquata (distinguished as var. watersi , see above) as well as W. subovoidea (as W. cucullata ). The illustrated Japanese specimens are W. subtorquata and it is unclear whether any of his local material was W. cucullata .

Figures

FIGURE 1. Watersipora subtorquata. A, B. Orange colonies from St Peter Port, Guernsey (no scale); C, D. Black colonies from St-Jacut-de-la-Mer, Brittany. Scale-bar marked in cm.

FIGURE 3. Scanning electron micrographs of Watersipora subtorquata from (A – C) St Peter Port, Guernsey and (D – F) St-Jacut-de-la-Mer, France. A, D are general views of zooids; B, E, show orifices; C, F, the left condyle at high magnification.

FIGURE 4. Light photomicrographs of orifices and opercula of Watersipora. Scale bar = 100 Μm. A – D, orifices; E – H, opercula. A. W. subtorquata, St-Jacut-de-la-Mer, France; B. W. subtorquata, St Peter Port, Guernsey; C. W. subovoidea, Arrawarra, New South Wales, Australia; D. W. subovoidea, Genoa, Italy; E. W. subtorquata, St-Jacut-de-la-Mer, France; F. W. subtorquata, St Peter Port, Guernsey; G. W. subovoidea, Naples, Italy; H. W. subovoidea, Genoa, Italy. In A – D, note the differences in condyles (the left one in each picture arrowed); in E – H, compare the sides of the central dark band, concave in W. subtorquata, parallel in W. subovoidea.