UC specimens and range limits for Ceramium pacificum

• Blue markers: specimen records
• Yellow marker: type locality, if present
• Red markers: endpoints of range from literature

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Illustration from DeCew's Guide to the Seaweeds of British Columbia, Washington, Oregon, and Northern California

Ceramium Roth 1797

Thalli usually erect, sometimes partially or wholly prostrate, saxicolous or epiphytic; axes cylindrical, freely branched. Branches of all orders corticated in transverse bands at nodes, in continuous layer throughout, or continuously in main axis and intermittently in younger branches. Branching alternate, predominantly unilateral, or irregular, frequently appearing dichotomous. Branch apices usually forcipate, sometimes straight. Axial filament of large cells, each cutting off transverse band of corticating cells at upper end (node), with or without downward or upward growth of smaller, usually angular cells from corticating band. Chloroplasts many, discoid to fusiform to elongate, denser in smaller cells. Cells uninucleate. Tetrasporangia embedded in cortical bands or projecting from them, with or without surrounding sterile cells. Procarps with 1 or 2 4-celled carpogonial branches arising from fertile pericentral cell, this forming auxiliary cell after fertilization; connecting cell present or lacking. Gonimoblasts borne at nodes, usually terminating further growth there but initiating several sterile branchlets from below, these serving as an involucre; gonimoblast rounded, with 1-3 gonimolobes, surrounded by gelatinous envelope. All cells of gonimoblast becoming carposporangia.

Ceramium pacificum (Coll.) Kyl.

Ceramium rubrum var. pacificum Collins 1913: 125. C. pacificum (Coll.) Kylin 1925: 61; Smith 1944: 326.

Thalli deep carmine, 5-18 cm tall; branches 200-300 µm diam. with long intervals between dichotomies, heavily proliferous with short radial branchlets; apices nodding or forcipate, occasionally with 1 or 2 short spines; cortications of small, angular cells, these closely packed above, becoming somewhat elongate below; tetrasporangia 35-40 µm diam., immersed in cortex of lateral branches, irregularly distributed; spermatangia in continuous patches in upper portions of branches, but not in youngest parts; gonimoblasts terminal on branches, surrounded by 5-7 stout, pointed sterile branches.

Locally abundant, epiphytic or saxicolous, midtidal to subtidal (10 m), Vancouver I., Br. Columbia, to Baja Calif. and Gulf of Calif. Type locality: Monterey, Calif.

Excerpt from Abbott, I. A., & Hollenberg, G. J. (1976). Marine algae of California. Stanford University Press, Stanford, California. xii [xiii] + 827 pp., 701 figs.