Cauloramphus magnus Dick and Ross, 1988

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 : 1077-1079

Cauloramphus magnus Dick and Ross, 1988

( Figure 10 )

Cauloramphus magnus Dick and Ross 1988, p 36 , Plates 2F, 10C, 13B.

Cauloramphus magnus: Grischenko 1997, p 163 ; 2004, p 40; Dick et al. 2005, p 3700, Figure 2E–H .

Cauloramphus cymbaeformis: Dick and Ross 1986, p 89 .

Cauloramphus spinifer: Kubota and Mawatari 1985a, p 80 , Figure 5 .

Material examined

ANC, ancestrular colony on rock (NHM 2006.2.27.32), colony on rock (NHM 2006.2.27.54), two extensive colonies on rock (NHM 2006.2.27.33–34); DIN, two colony fragments (NHM 2006.2.27.35). Additional material: 97 specimens; also several colonies on stones from Oshoro Bay , Hokkaido, Sea of Japan .

Description

Colony up to 2.8 cm across, light yellow to tan when alive. Zooids ( Figure 10A–F ) 0.57– 0.80 mm long (0.67¡ 0.07 mm), 0.32–0.48 mm wide (0.39¡ 0.04 mm), separated by a distinct, shallow groove. Cryptocyst ( Figure 10E ) narrow, sloping, coarsely granulate. Gymnocyst mostly reduced, smooth; occasionally tapering back between preceding zooids. Opesia 0.37–0.53 mm long (0.44¡ 0.04 mm), 0.20–0.30 mm wide (0.26¡ 0.03 mm), with crenulate margin, occupying 70–90% of zooidal length. Around mural rim, 11–18 spines; five or six distal spines hollow, straight, thicker and blunter than the rest; proximal 6–12 spines considerably thinner, sharp, curved, arched over opesia, well separated, occasionally meeting in midline; in some zooids, most proximal spine erect, hollow, thicker and longer than others, similar in length to distal spines. Avicularia ( Figure 10D ) generally rare, usually single when present, originating from gymnocyst between proximal and distal spines ( Figure 10C, D ); slightly longer than distal spines, with relatively long, thin pedicel gradually expanding into heavy, slightly curved chamber with terminally facing rostrum; mandible triangular, directed laterally. Embryos brooded endozooidally; fertile zooids with a small kenozooidal ooecium ( Figure 10E ) occupying distal portion of mural rim. Six pore chambers in each lateral wall and three in distal wall. Ancestrula ( Figure 10F ) tatiform, elongate-oval, 0.42 mm long, with about 16 spines along opesial margin. Ancestrula buds triplet of small zooids distally and distolaterally, each with 8–12 spines; ancestrula surrounded by six zooids.

Remarks

Specimens from Hokkaido agree well with the original description ( Dick and Ross 1988) of C. magnus from Kodiak Island, Gulf of Alaska. Both zooidal and opesial sizes are similar, but the spine number is greater at Akkeshi (11–18 compared to 11–14); a population from Ketchikan, Alaska ( Dick et al. 2005) also had more spines (12–18) than material from the type locality.

Distribution

This is a Boreal Pacific species, reported in the eastern Pacific from Kodiak Island in the western Gulf of Alaska ( Dick and Ross 1988) and Ketchikan in southern southeast Alaska ( Dick et al. 2005). In the western Pacific, it has been reported from the Commander Islands ( Grischenko 1997, 2004), though this material needs reexamination by SEM. We also collected this species at Oshoro Bay (Hokkaido), which is the southernmost known locality for C. magnus .

Figures

Figure 2. Dendrogram (below) showing similarity of sampling localities based on species presence/absence, and a map (above) showing the geographical distribution of three groups of sampling localities (circled) that are less than 70% similar in species composition between groups.

Figure 5. Electra asiatica n. sp. (A, G) NHM 2006.2.27.19; (B) NHM 2006.2.27.20; (C, D) NHM 2006.2.27.21; (E, F) NHM 2006.2.27.24. Colony from Ptichiy Island, Sea of Okhotsk (H). (A, B) Colonies radiating in coherent, fan-shaped lobes from the point of origin, unbleached; (C) colony margin with developing zooids, unbleached; (D) astogenetically mature zooids, unbleached; (E) astogenetically mature zooids, bleached; (F) astogenetically mature zooids with a small interzooidal kenozooid (lower right quadrant), bleached; (G) ancestrula and periancestrular zooids; enlargement of ancestrular area seen in panel (A), unbleached; (H) astogenetically mature zooids, bleached. Scale bars: 2 mm (A, B); 0.5 mm (C–H).

Figure 10. Cauloramphus magnus Dick and Ross, 1988. (A, C, D) NHM 2006.2.27.33–34; (B) NHM 2006.2.27.54; (E) NHM 2006.2.27.35; (F) NHM 2006.2.27.32. (A) Colony margin with developing zooids, unbleached; (B) same, bleached; (C) autozooids, unbleached; (D) close up of autozooids showing details of avicularia and spines, unbleached; (E) autozooids, bleached; (F) ancestrula and periancestrular zooids, bleached. Scale bars: 0.5 mm (A–C, E, F); 0.4 mm (D).