Cauloramphus magnus Dick and Ross, 1988

Dick, Matthew H., Grischenko, Andrei V. & Mawatari, Shunsuke F., 2005, Intertidal Bryozoa (Cheilostomata) of Ketchikan, Alaska, Journal of Natural History 39 (43), pp. 3687-3784 : 3700-3701

Cauloramphus magnus Dick and Ross, 1988

( Figure 2E–H)

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

Cauloramphus cymbaeformis: Dick and Ross 1986, p 89 .

Description

Colony. Unilaminar, encrusting, light brown, forming circular to irregular patches on hard substrates; largest observed 2 cm across.

Zooids. Oval, barrel-shaped, or rounded-hexagonal, sometimes proximally extended, delineated by a shallow groove, 0.60–0.75 mm long (average 50.653 mm, n 515, 3) by 0.38–0.48 mm wide (average 50.430 mm, n 515, 3). Entire basal wall calcified. Gymnocyst smooth; narrow or obscured if zooids crowded; sometimes evident proximally. Cryptocyst narrow, sloping; widest proximally, covered with coarse conical tubercles ( Figure 2G, H) that extend to area of orifice and sometimes on to distal marginal rim. Opesia variable in shape, 0.38–0.54 mm long (average 50.448 mm, n 515, 3) by 0.23–0.30 mm wide (average 50.251 mm, n 515, 3).

Spines ( Figure 2E, F). Twelve to 18, including four to six (modal number54, n 522, 4) stout, straight, erect orificial spines and 8–12 thin, acuminate, straight or curved opesial spines, well separated, angled over the opesia but often not meeting in midline.

Avicularia ( Figure 2F). Uncommon; arising from outer mural rim on one side of some zooids, between orificial and opesial spines; as long as longest opesial spines; short peduncle expanding to a broad chamber; rostrum at distal end, angled at 45 ° to long axis.

Ovicell. Embryos brooded inside the distal third to half of maternal zooid; ooecium exists as a small kenozooid budded by the maternal zooid and occupying the distal margin of the mural rim ( Figure 2G), evident as a raised, crescentic lip in brooding zooids.

Ancestrula . Not observed.

Remarks

Common at all three collecting sites at Ketchikan, this was by far the dominant species of Cauloramphus at Settlers Cove, an area of low circulation, high sedimentation, and freshwater seepage. A tendency to occur in these conditions was also noted at Kodiak ( Dick and Ross 1988). Specimens at Ketchikan agree well with the original description ( Dick and Ross 1988) of C. magnus from Kodiak. Zooid size is similar, but opesial measurements are a little smaller and spine number greater at Ketchikan. The diagnostic characters of this species are the narrow, raised mural rim; the narrow cryptocyst covered with coarse, conical tubercles that impart a serrate aspect to the opesial outline; the thin, straight or slightly curved, acuminate proximal spines generally separated from one another by two or more times their width; and avicularia with a short peduncle giving rise to a broad chamber. The species has an unruly appearance, with the opesial spines somewhat irregular in length, degree of curvature, and orientation; the tips meet at the midline in some zooids but not in others. Colonies are typically fouled with particulate debris.

Distribution

Gulf of Alaska; known from Kodiak ( Dick and Ross 1988) and Ketchikan.