Rhynchozoon splendens Hayward, 1988

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 : 2243-2245

Rhynchozoon splendens Hayward, 1988

( Figure 15A–C )

Rhynchozoon splendens Hayward 1988, p 335 , Plate 13f, g.

Rhynchozoon splendens: Ryland and Hayward 1992, p 294 , Figures 31f, 32a, b; Tilbrook et al. 2001, p 100, Figure 22A, B.

? Rhynchozoon rostratum: Winston and Heimberg 1986, p 38 , Figures 95–98.

Measurements

ZL, 0.48–0.70 (0.569¡0.061). ZW, 0.28–0.48 (0.386¡0.065). OrL, 0.09–0.10 (0.098¡0.004). OrW, 0.10–0.11 (0.108¡0.006). OvL, 0.175. OvW, 0.225 (ovicell n 51).

Description

One colony found; encrusting, multilaminar, light tan in colour, covered by shiny ectocyst; growing on a serpulid tube; 9 mm × 15 mm in extent. Zooids distinct only at margin; oval, hexagonal, or irregular in outline; oral spines lacking. Frontal wall ( Figure 15A, C ) moderately convex in young zooids, rugose, with interareolar buttresses between large areolae. Zooidal boundaries indistinct with age; frontal wall rugose; areolar openings enlarged. Primary orifice ( Figure 15B ) slightly broader than long, with low, broad, Ushaped sinus demarcated by condylar shelves; condyles rounded, conspicuous; orificial rim with around 19 denticles; becoming deeply immersed in peristome. Secondary orifice ( Figure 15C ) with up to six processes, usually conical or nodular but sometimes long and acute. Oral avicularium ( Figure 15A ) large, on a raised chamber, situated immediately proximolateral to orifice; rostrum often angled 60 ° or more from frontal plane of zooid, hooked at tip; mandible long-triangular, directed laterally or distolaterally; with age, oral avicularium immersed in peristome. Many zooids have a frontal avicularium ( Figure 15C ) pointing in any direction, the mandible equilateral or nearly so. Many of the frontal avicularia have a diamond-shaped rostrum, meaning that the proximal end of the rostrum is acute, as is the mandibular end. Ovicell ( Figure 15A, C ) completely immersed, opening low in peristome; endooecium showing as granulated, circular tabula in peristome.

Distribution

Broadly distributed throughout the Indo-West Pacific ( Tilbrook et al. 2001). This is the first record for the Hawaiian Islands.

Class STENOLAEMATA Borg, 1926

Order CYCLOSTOMATIDA Busk, 1852

Suborder CERIOPORINA Hagenow, 1851

Family DENSIPORIDAE Borg, 1944

Genus Disporella Gray, 1848

Disporella pristis ( MacGillivray, 1884)

( Figure 15D–F )

Discoporella pristis MacGillivray 1884, p 126 , Figure 3, 3a, b .

Disporella pristis: Gordon and Taylor 2001, p 260 , Figures 22–30.

Measurements

Diameter of peristome at colony margin 0.05–0.07 (0.060¡0.006); diameter of kenozooidal opening near colony margin 0.04–0.07 (0.056¡0.009).

Description

Based on a single circular colony 3.5 mm in diameter. Colony ( Figure 15D ) mound-shaped, adnate, the lamellar margin slightly raised; whitish in colour. Peristomes distinct, not connate, but organized in approximately radial columns with the zooids offset from one column to the next, so that they are quincuncially arranged. Entire surface of colony finely granulated ( Figure 15E, F ), including the marginal lamella, which shows no radial striae. Peristomes with elevated extension on macular side that is semicircular in transverse section and in marginal zooids is often prolonged at end into as many as six long, sharp processes ( Figure 15F ). Interior walls of kenozooids with sparse, small, sharp denticles. Centre of colony occupied by a brood chamber ( Figure 15D ) that is about one-third of colony diameter in extent, consisting of two elongate, irregular lobes; surface of chamber irregularly porous, in the process of becoming thickened with reticulate calcification. One oeciostome present ( Figure 15E ), located at abmacular edge of brood chamber, the opening oval, raised on a low peristome; internal surface of oeciostome covered with minute spines.

Remarks

Our specimen agrees well with the description by Gordon and Taylor (2001) of small, neanic colonies of this species. According to these authors, colonies can become quite large, up to 6 cm in extent, and with more than a hundred maculae.

Distribution

Broadly distributed in the Indo-West Pacific from Japan through Indonesia, New Zealand, the Great Barrier Reef, southern Australia, eastern and southern Africa (referenced in synonymies by Gordon and Taylor 2001). This is the first record for the Hawaiian Islands.

Figures

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 15. (A–C) Rhynchozoon splendens Hayward: (A) ovicellate zooids, showing asymmetrically orientated oral avicularia; (B) enlargement of primary orifice; (C) autozooids and ovicellate zooids; diamond-shaped rostra of frontal avicularia are also evident. (D–F) Disporella pristis MacGillivray: (D) partial view of entire colony, showing irregular brood chamber in centre, with oeciostome; (E) enlargement of part of brood chamber and oeciostome (top centre); (F) colony margin, showing characteristically granulated marginal lamina and peristomes ending in long processes. All specimens bleached. Scale bars: 500 Mm (A, C); 50 Mm (B); 1 mm (D); 400 Mm (E, F).