Hippopodina iririkiensis Tilbrook, 1999

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 : 2229-2230

Hippopodina iririkiensis Tilbrook, 1999

( Figure 11A )

Hippopodina iririkiensis Tilbrook 1999, p 454 , Figure 2a, c, e .

Hippopodina iririkiensis: Tilbrook et al. 2001, p 90 , Figure 18B; Tilbrook 2006, p 245.

Measurements ZL, 0.85–1.03 (0.940¡0.062). ZW, 0.68–0.88 (0.735¡0.063). OrL, 0.19–0.21

(0.207¡0.007). OrW, 0.20–0.24 (0.216¡0.0112). OvL, 0.53–0.65 (0.573¡0.051). OvW, 0.50–0.60 (0.553¡0.042).

Description

Colony unilaminar, encrusting, glistening, white with a tinge of lavender; zooids large; frontal wall moderately inflated, granulated, completely covered with minute pores. Orifice has been described as ‘‘keyhole-shaped’’ or ‘‘bell-shaped’’, with a shallow poster separated from a longer anter by obtuse-triangular condyles; proximal orificial margin concave; oral spines lacking. Avicularia situated distolateral to orifice, usually single, sometimes paired; ovicell about as broad as long, partly embedded in frontal wall of distal zooid, raised, globose, with the same texture and perforation as the frontal wall.

Remarks

Several of the triad ancestrular complexes characteristic of H. iririkiensis were observed among the Hawaiian specimens. This species is distinguished from a similar congener, H. feegeensis , in having a concave rather than a straight proximal orificial margin. Hippopodina iririkiensis was the most widely distributed species found in the study; it occurred at all three sites where bryozoans were found, was the only bryozoan species found at Whittington Beach, and was the spatially and numerically dominant species at Kealakekua Bay.

Distribution

Tropical Indo-West Pacific: Vanuatu, North Queensland, Fiji, Philippines, Mauritius, Red Sea; Mediterranean (for references, see synonymies). This is the first record for the Hawaiian Islands.

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 11. (A) Hippopodina iririkiensis Tilbrook: autozooids and ovicellate zooids. (B, C) Cosciniopsis lonchaea (Busk): (B) autozooids and ovicellate zooids; (C) enlargement showing shapes of primary and secondary orifices. (D, E) Calyptotheca kapaaensis n. sp., holotype (NHM 2006.7.21.15): (D) autozooids; (E) enlargement of primary orifice and suboral avicularium. (F) Cheiloporina haddoni Harmer: autozooids and one ovicellate zooid (upper left). All specimens bleached. Scale bars: 1 mm (A, B, F); 200 Mm (C); 500 Mm (D); 100 Mm (E).