Parellisina albida ( Hincks, 1880 )

Dick, Matthew H., Tilbrook, Kevin J. & Mawatari, Shunsuke F., 2006, Diversity and taxonomy of rocky-intertidal Bryozoa on the Island of Hawaii, USA, Journal of Natural History 40 (38 - 40), pp. 2197-2257 : 2206-2207

Parellisina albida ( Hincks, 1880)

( Figure 3D )

Membranipora albida Hincks 1880, p 81 , Plate 10, Figure 5 .

Parellisina albida: Hayward and Ryland 1995, p 538 .

Parellisina curvirostris: Ryland and Hayward 1992, p 229 , Figure 2d ;? Soule et al. 1988,

p 147.

Measurements ZL, 0.50–0.70 (0.590¡0.076). ZW, 0.33–0.43 (0.366¡0.032). OpL, 0.35–0.46

(0.397¡0.033). OpW, 0.21–0.28 (0.245¡0.018). OvL, 0.20–0.26 (0.232¡0.027). OvW, 0.20–0.28 (0.245¡0.028) (ovicell n 57).

Description

Colony unilaminar, encrusting, coarse, tan in colour. Zooids moderately large, separated by a deep groove. Gymnocyst negligible laterally, sometimes a little wider proximally, with one or a pair of minute uniporous openings evident frontally in angles of proximal gymnocyst, surrounded by a wide, finely granulated zone (these marginated unipores perhaps represent incipient kenozooids). Cryptocyst narrow, sloping, more or less constant in width proximally and laterally, with coarse granulation. Opesia occupying almost whole of frontal area, oval or somewhat irregular. Subtriangular or quadrate spaces between zooids occupied by large interzooidal avicularia, each associated with a distal kenozooid; rostrum raised, laterally curved and slightly twisted, one rostral edge higher than the other; mandible broad at base, extended into sharp latero-basal lobes that taper rapidly to a narrow, long-triangular, almost setose mandible with a hooked tip; opesia of kenozooid irregular in shape, subtriangular, oval, or irregular, and variable in size even within a colony, generally equal to or larger than avicularian opesia. Spines lacking. Ovicell raised, globose, narrower than zooid, imperforate, the surface roughened with low, rounded tubercles, the proximal margin concave.

Remarks

Both this species and P. falcata ( MacGillivray, 1869) , reported from Australia, have a laterally curved avicularian mandible with sharp lateral extensions at the base; P. falcata differs in having zooids with a wide proximal cryptocyst ( Osburn 1949). Although P. curvirostris ( Hincks, 1862) , originally described from Britain, has been considered circumglobal in warmtemperate and subtropical waters, many Pacific records of this species need to be re-examined. Our material differs from British P. curvirostris in having a granulated cryptocyst on the kenozooid, marginated pores on the proximal zooidal gymnocyst, and much larger zooids. Tilbrook (2006) recently recorded two species of Parellisina from the Solomon Islands, P. suluensis ( Osburn 1949) and a new species, P. mboliensis .

Distribution

Originally described from an unspecified locality in the Indo-Malayan area ( Hincks 1880), P. albida has subsequently been reported from the Great Barrier Reef, Australia ( Ryland and Hayward 1992; Hayward and Ryland 1995). Our material might be conspecific with nominal P. curvirostris previously reported from Hawaii ( Soule et al. 1988).

Figures

Figure 2. Photographs of rock-pile habitats examined at study sites on the Island of Hawaii; all taken within an hour of low tide (20.03 to +0.15 m referenced to mean lower low water). (A) Kealakekua Bay; study site is shallow inlet beginning at centre and extending to just below left centre; plastic kayak at upper right indicates scale. (B) Whittington Beach Park; sheltered lagoon inside benchrock barrier, part of which can be seen in distance at far upper right; scale indicated by water bottle at lower left. (C) Kapa’a Beach Park; an exposed site with roundedboulder beaches (centre) and solid benchrock (in distance, upper right); sampling site was a tidepool in the benchrock just beyond the upper right of the photograph. (D) Kiholo Bay; entrance to large lagoon separated from the sea by a long barrier spit, on which palm and other trees are growing; end of spit is seen just above right centre, with lagoon evident beyond that in the distance; the shallow area with boulders protruding from water, left to right just below centre, was examined for bryozoans; photograph taken about an hour before low tide.

Figure 3. (A–C) Alderina flaventa n. sp., holotype (NHM 2006.7.21.1): (A) group of autozooids and ovicellate zooids; (B) ovicellate zooid; (C) colony margin showing uniporous septula. (D) Parellisina albida (Hincks): autozooids, ovicellate zooid, and interzooidal avicularia. All specimens bleached. Scale bars: 500 Mm (A, C, D); 400 Mm (B).

Figure 5. (A, B) Antropora minor (Hincks): (A) autozooids, bleached; (B) autozooids, bleached; zooid at right is a brooding zooid, with a raised, smooth distal margin that may represent a vestigial ovicell. (C) Beania discodermiae (Ortmann): autozooids, unbleached. (D) Micropora rimulata Canu and Bassler: autozooids and ovicellate zooids, bleached. Scale bars: 200 Mm (A, B); 500 Mm (C, D).