CRIBRILINIDAE Hincks, 1879

Grischenko, Andrei V., Dick, Matthew H. & Mawatari, Shunsuke F., 2007, Diversity and taxonomy of intertidal Bryozoa (Cheilostomata) at Akkeshi Bay, Hokkaido, Japan, Journal of Natural History 41 (17 - 20), pp. 1047-1161 : 1093-1095

Family CRIBRILINIDAE Hincks, 1879

Genus Cribrilina Gray, 1848 Cribrilina annulata ( Fabricius, 1780)

( Figure 17 ) Cellepora annulata Fabricius 1780, p 436 . Cribrilina annulata: Robertson 1900, p 326 ; 1908, p 280; O’Donoghue and O’Donoghue 1923, p 172; 1926, p 96; Osburn 1950, p 177, Plate 28, Figure 7 ; Androsova 1958,

p 124, Figure 39 ; Kluge 1962, p 390, Figure 247; 1975, p 470, Figure 247; Mawatari and Mawatari 1981b, p 49; Kubota and Mawatari 1985b, p 195, Figure 1 ; Dick and Ross 1988, p 51, Plate 4C; Kubanin 1997, p 123; Grischenko 1997, p 171; 2004, p 40; Hayward and Ryland 1998, p 314, Figure 110; Dick et al. 2005, p 3718, Figure 7A, B .

Material examined

ANC, colony on rock (NHM 2006.2.27.31); DIN, colony on rock (NHM 2006.2.27.50), colony on rock (NHM 2006.2.27.51); BAC, ancestrular colony on bivalve shell (NHM 2006.2.27.52). Additional material: 436 specimens .

Description

Colony encrusting, coherent, forming irregularly circular sheets up to 2.7 cm across; lightyellow, red, or pink when alive; unilaminar, but often with scattered frontally budded dwarf zooids. Autozooids ( Figure 17A, B ) rounded-hexagonal to oval, 0.51–0.65 mm long (0.56¡ 0.04 mm), 0.30–0.43 mm wide (0.36¡ 0.03 mm), separated by a deep groove. Frontal wall moderately convex, consisting of five to seven pairs of flattened, fused costae, with 6–10 intercostal pores in a transverse series between costae. Distalmost pair of costae wider and heavier than the rest, forming thickened proximal border of secondary orifice, often rising medially to a pointed suboral umbo, sometimes incompletely fused. Secondary orifice oval, 0.09–0.13 mm long (0.10¡ 0.01 mm), 0.15–0.20 mm wide (0.17¡ 0.01 mm), flanked by a pair of hollow, erect spines distolaterally, with a shorter, tapering hollow spine in midline, or sometimes two, occasionally fused. Ovicellate zooids absent in primary layer. Frontally budded dwarf ovicellate zooids ( Figure 17A, C ), 0.22–0.33 mm long (0.29¡ 0.02 mm), 0.19– 0.25 mm wide (0.22¡ 0.02 mm), occupy central region of colony, orientated in any direction; frontal wall reduced, consisting of three or four fused costae, including the pair of heavier subapertural costae comprising proximal lip of longitudinally compressed orifice and an additional one or two others, with a few intercostal pores between them. Ovicell of dwarf zooids derived from two pairs of spines, one pair broadened and thickened to form proximal border of ovicell, the other fused to form cap-like distal wall of ovicell; ovicells of dwarf zooids perforated on top with one to four pores that sometimes merge with one another; pseudopores at tips of thick proximal ovicellar costae appear as additional small perforations. Avicularia lacking. Zooids with two distal and two distolateral basal pore chambers. Ancestrula ( Figure 17D ) identical in form to autozooid, 0.35 mm long, 0.23 mm wide, with five orificial spines. Ancestrula buds triplet of zooids distally.

Remarks

In the material examined, ovicells were found only on dwarf zooids, usually concentrated densely in the centre of the colony. Dick et al. (2005) noted that differences in the fusion of distal orificial spines, form of the ovicell, and ancestrular budding patterns exist in populations across the range of this putatively circumpolar species and that nominal C. annulata may comprise a complex of cryptic species. However, resolution of this issue will require monographic treatment and is beyond the scope of the present study.

Distribution

This is considered a circumpolar Arctic-Boreal species ( Kluge 1962, 1975; Gontar and Denisenko 1989). In the eastern Pacific, it has previously been reported from Kodiak, Cordova, Yakutat, and Ketchikan in Alaska ( Robertson 1900; Osburn 1950; Dick and Ross 1988; Dick et al. 2005), and from British Columbia ( O’Donoghue and O’Donoghue 1923, 1926). On the Asian side, it has been reported from the Commander Islands, southeastern Kamchatka, the Kuril Islands, Sakhalin Island, and Primorye on Peter the Great Gulf ( Kluge 1961; Gontar 1980; Grischenko 1997, 2004; Kubanin 1997). In Japan it is known from Akkeshi, Muroran, and Shirikishinai on the Pacific coast of Hokkaido (Mawatari and Matawari 1981b), and from Oshoro Bay on the Sea of Japan side ( Kubota and Mawatari 1985b).

Figures

Figure 1. Map of Akkeshi Bay showing the 10 sampling stations (filled squares); 5, 10, and 20 m depth contours are indicated. Inset shows the location of Akkeshi Bay on Hokkaido Island, northern Japan.

Figure 7. Callopora craticula (Alder, 1856). NHM 2006.2.27.29. (A) General view of colony fragment, unbleached; (B) immature zooids near colony margin, unbleached; (C) mature zooids showing ovicells and associated avicularia, unbleached; (D) group of immature zooids and vicarious avicularium on right, unbleached. Scale bars: 0.5 mm (A); 0.2 mm (B–D).

Figure 17. Cribrilina annulata (Fabricius, 1780). (A) NHM 2006.2.27.50; (B, C) NHM 2006.2.27.51; (D) NHM 2006.2.27.52. (A) Zooids with developing secondary layer of dwarf zooids, from region nearly colony margin; (B) immature zooids; (C) autozooids densely covered with numerous ovicellate dwarf zooids; (D) ancestrula with periancestrular zooids. Scale bars: 0.5 mm.

Figure 39. Hippoporella kurilensis (Gontar, 1979). NHM 2006.2.27.103. (A) Colony margin with developing zooids; (B) immature zooids; (C) zooids near colony margin, one with hypertrophied suboral avicularium; (D) zooids with developing ovicells; (E) mature zooids with immersed ovicells; (F) ancestrular region covered with large adventitious avicularia. Scale bars: 0.4 mm (A–C); 0.5 mm (D–F).