UC specimens and range limits for Antithamnionella pacifica

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

View map from the Consortium of Pacific Northwest Herbaria

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

Antithamnionella Lyle 1922 (Contributed by Elise M. Wollaston)

Thalli rose red, erect or of erect branches arising from prostrate bases; axes monosiphonous, uncorticated, bearing whorls of 1-4 branchlets on each axial cell, these initiated in irregular or unilateral sequence from curved branch apices. Branchlets rebranched or unbranched, with basal cells similar in size to adjacent cells. Cells uninucleate. Gland cells cut off laterally, usually from central or inner cells of branchlets. Tetrasporangia ovoid or subspherical, cruciately or tetrahedrally divided, sessile or pedicellate on inner cells of branchlets. Spermatangia on branched spermatangia branches borne adaxially on branchlets. Carpogonial branches 4-celled, borne singly at branch apices on basal cells of immature branchlets, these not elongating more than 1 or 2 cells beyond supporting cell; after fertilization, branch apex ceasing to elongate and deflecting to one side as gonimoblast matures. Most cells of gonimoblast becoming carposporangia, these formed successively in lobed or somewhat elongate groups.

Antithamnionella pacifica (Harv.) Woll.

Callithamnion floccosum var. pacificum Harvey 1862: 176. Antithamnionella pacifica (Harv.) Wollaston 1971: 87. Antithamnion floccosum var. pacificum (Harv.) Setchell & Gardner 1903: 341. Antithamnion pacificum (Harv.) Kylin 1925: 47; Smith 1944: 310.

Thallus erect, the lower axes often intertwined, with cell length to 20(30) times diam.; branchlets unbranched (except for short fertile branches), usually 2 opposite (sometimes 1) on central or upper part of each axial cell; lateral branches arising in place of branchlets; gland cells lacking or very rare; tetrasporangia ovoid, cruciately (often appearing tetrahedrally) divided, terminal or lateral on short branches on adaxial side of inner cells of branchlets; carpogonial branches arising singly at branch apices on basal cells of young branchlets; carposporangia in somewhat elongate groups.

Antithamnionella pacifica var. pacifica

Thallus to 10 cm tall; vegetative and reproductive features much as for var. uncinata, but characterized by straight apices of branchlets and the axial cells much longer (20-30 times) than diam.

Common, subtidal and epiphytic on upper portions of stipes of Nereocystis or other large algae, Alaska to Baja Calif. Type locality: Vancouver I., Br. Columbia.

Antithamnionella pacifica var. uncinata (Gardn.) Woll.

Antithamnion uncinatum Gardner 1927a: 408; Smith 1944: 311. Antithamnionella pacifica var. uncinata (Gardn.) Wollaston 1971: 88.

Vegetative and reproductive features much as for var. pacifica, but characterized by outwardly curved circinnate apices of branchlets, especially in lower parts of thallus, and often with relatively shorter (less than 8 times diam.) axial cells (especially in less actively growing plants and in mature parts of thallus).

Common on Nereocystis or other large algae, Alaska to Baja Calif. Type locality: Dillon Beach (Marin Co.,), 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.