UC specimens and range limits for Scytosiphon lomentaria

• 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: Broadly distributed in the Atlantic and Pacific, possibly via introductions. Because this is a complex of cryptic species, identifications are difficult and likely to be in error.

Status: This name represents a complex of cryptic species. In rbcL, ITS and rbcL-sp-S analyses (Cho et al. 2007), S. lomentaria formed a clade consisting of Pacific and European subclades. The nucleotide differences in rbcL were large enough to indicate two cryptic species. In the ITS analyses the Pacific clade was further divided into two well-supported subclades, both of which included samples from Korea, Japan, Oregon, Washington and New Zealand. Anthropogenic introductions are likely because identical sequences were shared between localities. In southern California, the gametophyte of Scytosiphon canaliculatus is probably confused with this species.

Habitat: Low intertidal pools - shallow subtidal; often opportunistic in disturbed habitats

Life History: Variable and plastic, affected by daylength, temperature, and geography, involving tubular erect isogamous gametophytes bearing plurilocular sporangia and crustose Ralfsia-like sporophytes bearing unilocular thalli, but the two phases alternating facultatively with or without gamete fusion (Kogame et al. 2005). See DeCew's Guide for more references.

Search Sequences in GenBank

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

Scytosiphon C. Agardh 1820

Thallus usually tufted, with several to numerous erect fronds arising from discoid base. Erect parts simple, solid or mostly tubular, cylindrical or flattened, commonly with frequent constrictions when tubular. Inner cells of thallus elongate, thick-walled; cortical layer with cells progressively smaller toward surface. Phaeophycean hairs commonly present. Unangia borne on crustose stage resembling Ralfsia. Plurangia forming on extensive surface areas.

Scytosiphon lomentaria (Lyngb.) J. Ag.

Chorda lomentaria Lyngbye 1819: 74. Scytosiphon lomentaria (Lyngb.) J. Agardh 1848: 126; Setchell & Gardner 1925: 531; Smith 1944: 129; Wynne 1969a.: 31.

Thallus erect, parts 20-30(70) cm tall, mostly 4-6 mm diam., tubular, usually constricted; hairs arising singly on superficial cells; plurangia 4-8 µm diam., 40-65 µm long; colorless, unicellular structures resembling paraphyses (ascocysts?) present among plurangia; unangia occurring on crustose stage of plant.

Abundant in localized areas on sheltered rocks in lower intertidal, or in shallow upper-intertidal pools. Bering Sea to Baja Calif. Widely distributed. Type locality: Denmark.

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: This combination is traditionally but incorrectly attributed to J. Agardh 1848.