UC specimens and range limits for Petalonia fascia

• 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: Widely distributed from Alaska through Baja California, Mexico; Europe.

Status: This broadly distributed species is a complex of cryptic species (Lee et al. 2014) that has not yet been teased apart.

Habitat: Upper to mid intertidal on rocks, shells and the surf grass, Phyllospadix.

Life History: Heteromorphic and diphasic life history with a large erect gametophyte and a small discoid sporophyte; plurizoids (probably asexual plurizoids and unfused gametes) directly produce prostrate systems bearing erect thalli, or they form prostrate discoid thalli bearing unilocular sporangia (Wynne 1969; Nakamura & Tatewaki 1975; Fletcher 1987; Kogame & Kawai 1993).

Search Sequences in GenBank

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

Petalonia Derbès & Solier 1850

Thalli annual, 1 or more erect blades arising from small, discoid base. Blades linear to broadly lanceolate, with small tufts of multicellular hairs; surface cells small, subcubical; medulla with several layers of much larger colorless cells, the plurangia uniseriate, ultimately covering both surfaces of blades and maturing progressively from apex to base of blades. Unangia borne at base of free, pigmented paraphyses on very small, thin, Ralfsia-like, crustose stage developing from plurangial motile cells (swarmers).

Petalonia fascia (Müll.) Kuntze

Fucus fascia Müller 1775-82 (1778): 7. Petalonia fascia (Müll.) Kuntze 1898: 419; Wynne 1969a: 17. Ilea fascia (Müll.) Fries 1835: 321 (in part); Setchell & Gardner 1925: 535; Smith 1944: 126. P. debilis sensu Hollenberg & Abbott 1966: 23 (incl. synonymy).

Blades to 35 cm tall, 30 cm broad, of variable width in a given tuft, linear-lanceolate, with tapering apex and cuneate base, greenish-brown to dark brown; plurangia 6-8 cells long, uniseriate.

Frequent on upper to midtidal rocks, or epiphytic on Phyllospadix, N. Japan and Alaska to Isla Magdalena, Baja Calif. Widely distributed; also in Europe and Chile. Type locality: Norway.

It seems best to consider the various forms listed by Setchell and Gardner (1925: 536) as representing a single variable species.

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