UC specimens and range limits for Chaetomorpha aerea

• 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

Notes: Northern record: Cape Perpetua, Oregon, OSC-A-000185; in California, just north of Moonstone Beach, Humboldt Co. Southern records in California: San Clemente Island; Bird Rock, La Jolla, San Diego Co., WTU-A-000264; San Diego, San Diego Co. (collected in 1895).

Status: This genus needs to be re-examined for species on the west coast because most studies have addressed European or east coast species with the same names. A chief diagnostic character is cell dimension, which is unreliable. Several other species of Chaetomorpha have been recorded for California, but need confirmation.

Habitat: Upper (in pools) or mid-intertidal rock, cobble or concrete, often associated with sand

Life History: Not investigated in Pacific coast populations. In Europe, alternation of isomorphic phases, a sporophyte that produces quadriflagellate zoospores alternating with unisexual gametophytes that produce biflagellate isogametes; parthenogenetic development of gametophytes by unfused gametes (Kornmann 1972a; Köhler 1956).

Search Sequences in GenBank

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

Chaetomorpha Kützing 1845

Thalli uniseriate unbranched filaments, solitary or in tufts, attached or free-floating, entangled, epiphytic. Holdfast discoid or with nonseptate rhizoidal filaments growing from proximal end of elongate basal cell. Cells multinucleate, most cells fairly uniform in size in a given thallus; size and shape of basal cell diagnostic in taxonomy but probably not reliable. Chloroplast parietal, reticulate (discoid with age), with numerous pyrenoids. Asexual reproduction by fragmentation, or by quadriflagellate zoospores produced in large numbers from undifferentiated vegetative cells. Sexual reproduction by biflagellate gametes. Life stages isomorphic.

Chaetomorpha linum (Müll.) Kütz.

Conferva linum Müller 1775: 771. Chaetomorpha linum (Müll.) Kützing 1845: 204. Chaetomorpha aerea (Dillwyn) Kütz. 1849: 379; Smith 1944: 56. Conferva aerea Dillw. 1809: pl. 80.

Thalli grass-green to yellowish-green, 4-8(30) cm tall, the filaments straight, basally attached, gregarious; delicate rhizoids from proximal end of basal cell sometimes forming disk; basal cell tapering downward, 4-6 times longer than ordinary vegetative cell; vegetative cells short-cylindrical, 125-400 µm diam., 0.5-2 times as long, somewhat constricted; fertile cells barrel-shaped to subglobose, 400-600 µm diam.

Abundant, on shaded banks or flat rocks, lining sandy tidepools or floating, high to midtidal, Bolinas (Marin Co.) to San Diego, Calif. Type material from England and Wales.

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

Notes: Abbott & Hollenberg (1976) treat Chaetomorpha aerea and C. linum as the attached and free-floating stage, respectively, of one species, C. linum. Blair (1983: 180), who recognized C. aerea and C. linum as distinct species, cited a collection of C. linum from Coos Co., Oregon, and one from "California: Santa Clara Co., San Martin Is." The latter record, however, is erroneous, being based on confusion between Isla San Martin, Baja California (the provenance of the specimen) and the town of San Martin in California.

In southern California, there is a subtidal, curly, entangled Chaetomorpha that can form large fluffy masses and that may be the same as Blair's Isla San Martin specimen. In this treatment, we refer to this unattached species as C. linum, without knowing its relationship to the Atlantic species with this name.