Callopora sarae, Grischenko & Dick & Mawatari, 2007

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 : 1072-1074

Callopora sarae new species

( Figure 8 )

Diagnosis

Opesia 60–85% of zooidal length; 17–25 spines with enlarged, cylindrical bases around mural rim, including three pairs of thick, vertical distal spines (the most proximal pair by far heavier than the rest), 12–17 thin proximal spines arched over opesia, and often one or two additional thin spines present on outer distolateral gymnocyst; avicularia small, on lateral or proximal gymnocyst, usually single, rarely paired, associated with distal half of ovicell in mature zooids; ovicell with a wide transverse tabula; transverse ridge often enlarged into a median knob; proximal ovicell margin raised as a wide lip; zooids interconnect by multiporous septula.

Etymology

The species is named in honour of Sarah Taranto, who collected the holotype specimen.

Material examined

Holotype: MAC, colony on rock (NHM 2006.2.27.4). Paratypes: MAC, colony on rock (NHM 2006.2.27.3); MAC, colony on rock (NHM 2006.2.27.5). Additional material: four specimens.

Description

Colony encrusting, unilaminar, multiserial, irregular in shape, up to 2.1 cm in maximum dimension, whitish to light yellow in colour when alive. Zooids ( Figure 8A–F ) elongate-oval, hexagonal, or pyriform, 0.38–0.60 mm long (0.50¡ 0.06 mm), 0.20–0.33 mm wide (0.28¡ 0.04 mm), demarcated by deep, narrow grooves when young, more closely appressed when mature. Mural rim raised, sharp, smooth. Cryptocyst reduced, narrow, with parallel horizontal folds, non-granulated, sloping abruptly below marginal rim. Distal and lateral gymnocyst smooth, sloping and narrow; proximal gymnocyst variably developed, occasionally tapering, up to 25% of zooid length, entirely covered by ovicell in mature zooids. Opesia ( Figure 8C, D ) oval to pyriform, widest in middle or proximally, 0.27–0.38 mm long (0.33¡ 0.03 mm), 0.16–0.24 mm wide (0.20¡ 0.02 mm), occupying 60–85% of zooidal length. Around mural rim 17–25 spines ( Figure 8A, B ) with enlarged, cylindrical bases; the three distal pairs thick, hollow, long, vertical, leaning slightly over opesia but curving outwards, their bases heavily calcified and rising above plane of mural rim; proximal 12–17 spines thinner, acuminate, arched over opesia, becoming progressively shorter towards proximal end of zooid; in addition, one or two thin, short tubular spines often present on outer distolateral gymnocyst. Small frontal avicularium ( Figure 8C, E, F ) with raised chamber occupies outer slope of lateral gymnocyst on one side, usually near middle, sometimes more proximally or on proximal gymnocyst; mandible triangular, with acute, hooked tip, pointing in any direction; rarely avicularia paired, laterally arranged on opposite sides of opesia, or on lateral and proximal gymnocyst; some zooids lack avicularia altogether; ovicellate zooids have a similarly small avicularium on distal half of ovicell, pointing distally or distolaterally. Ovicells ( Figure 8F ) hyperstomial, prominent, spherical, imperforate, about as long as broad, 0.18– 0.23 mm long (0.20¡ 0.02 mm), 0.16–0.28 mm wide (0.21¡ 0.03 mm); outer surface smooth; proximal margin of ectooecium enlarged as a thick transverse ridge, often with a blunt, wide median knob; proximal margin of endooecium a wide, raised lip; between entooecial and ectooecial margins is a transverse, dumbbell-shaped tabula covered by ectocyst; ovicell heavily calcified, entirely covering proximal gymnocyst of zooid beneath and reaching lateral walls of neighbouring zooids, extending between spine bases. Four oval to circular multiporous septula in each lateral wall and two septula in transverse wall. Ancestrula not observed.

Remarks

Callopora sarae is similar to C. corniculifera ( Hincks, 1882) , a Boreal species reported from both sides of the Pacific (see Soule et al. 1995, p 66, Plate 16A, B), in having small lateral avicularia. However, C. corniculifera has larger zooids (0.65–0.70 mm long by 0.45– 0.50 mm wide); roughly half the number of spines (10–12); and a smaller avicularium situated along the lateral margin only, in line with the proximal orificial margin.

Callopora decidua Dick and Ross, 1988 , described from Kodiak, Alaska, also has a high spine number, 14–21, including three pairs of heavy distal spines, as well as small, single or paired lateral avicularia; however, in this species, proximal avicularia are rare unless preceded by an ovicell, and when they occur, the rostrum is long and curved.

Callopora longispinosa Androsova, 1958 , distributed in the northwestern Pacific, is similar to C. sarae in having two or three pairs of long, stout distal spines, occasionally 1.5–2 times or more the length of the zooid ( Grischenko 1997); however, this species differs from C. sarae in having fewer proximal spines (four to six); avicularia rare and located on the proximal gymnocyst only; and the spherical ovicells weakly calcified and not associated with avicularia.

Distribution

Akkeshi Bay is the only known locality.

Figures

Figure 8. Callopora sarae n. sp. (A, E) NHM 2006.2.27.5; (B) NHM 2006.2.27.3; (C, D, F) NHM 2006.2.27.4. (A) Zooids at colony edge, unbleached; (B) immature zooids with spines, lateral and proximal avicularia, unbleached; (C) immature zooids, showing bases of spines and lateral avicularia, bleached; (D) two immature zooids showing bases of additional spines on outer distolateral gymnocyst, bleached; (E) mature zooids with ovicells and associated avicularia, unbleached; (F) mature zooids with heavily calcified ovicells, bleached. Scale bars: 0.5 mm (A–C, E, F); 0.4 mm (D).