UC specimens and range limits for Acrosiphonia coalita

• 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 records: Buldir Island, Alaska, U. Alaska Museum A10636; Southern records in UC: Government Point, Santa Barbara Co.; Santa Rosa Island; San Pedro, Los Angeles Co. (1899 only; habitat has changed extensively since).

Status: This species is the most common and the easiest to identify in the genus, but specimens are likely to represent a complex of species. Species delimitation in Acrosiphonia is difficult due to environmental plasticity in morphological (e.g., size, branching) and anatomical (e.g., cell length/width ratios, presence and absence of hook cells) characters (Sussmann et al. 1999). Saunders and Kucera (2010) tested several markers on specimens of A. coalita from British Columbia, Canada and A. arcta from the east coast of Canada and discovered cryptic taxa in this genus. Lindstrom & Hanic (2005) sequenced nuclear ITS and 18S rRNA from a specimen from Baker Beach, San Francisco Co., and demonstrated its relationship to Chlorothrix and Urospora. Acrosiphonia saxatilis and A. mertensii have also been reported for California, but their identities have not been confirmed by DNA sequence.

Habitat: Mid-low intertidal, sometimes associated with sand

Life History: An alternation of free-living unisexual filamentous gametophytes with a unicellular sporophyte endophytic in the petrocelis-stage (Petrocelis franciscana Setchell & Gardner) of Mastocarpus by means of biflagellate isogametes and quadriflagellate zoospores (Hanic 1965; Fan 1959; Hollenberg 1958b). Endophytic green cells ("Chlorochytrium inclusum" and "Codiolum petrocelidis") in Mastocarpus and Mazzaella splendens from southwestern British Columbia, Canada have been identified as the diploid phase of species of Acrosiphonia. ITS sequences from a "Codiolum" isolate matched those from A. coalita specimens from Monterey Bay, California, Friday Harbor, Washington and Bamfield, British Columbia, Canada (Sussmann et al. 1999). Asexual reproduction in spring via vegetative growth from the basal remnants of haploid plants from the previous year may account for this species' success in disturbed environments and for the maintenance of seasonal (summer) gametophytes (Sussman & DeWreede 2007).

Search Sequences in GenBank

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

Spongomorpha Kützing 1843

Thallus of profusely branched, uniseriate filaments, the major axes entangled in ropelike strands, spongy in texture. Branches ropelike primarily because of hooklike lateral branchlets entangling adjacent branchlets, and because of lateral fusion of lower axes by descending rhizoids. Terminal branchlets usually rebranched, rarely unilateral in position. Terminal cells elongate, cell division usually intercalary. Cells multinucleate. Chloroplast single, parietal, reticulate, with numerous pyrenoids. Asexual reproduction by fragmentation, or by biflagellate zoospores from undifferentiated vegetative cells functioning as sporangia. Sexual reproduction isogamous, the gametes formed from undifferentiated vegetative cells; as far as is known these large gametangial plants alternating with unicellular "Codiolum" stage or "Chlorochytrium" stage, from which zoospores give rise to gametangial phase. Cytological details of unicellular stage unknown.

Spongomorpha coalita (Rupr.) Coll.

Conferva coalita Ruprecht 1851: 404. Spongomorpha coalita (Rupr.) Collins 1909a: 361; Smith 1944: 65; Scagel 1966: 97.

Thallus tufted, bright grass-green to dark green, frequently with yellowish tips, 25-45 cm tall, having appearance of branched, much-frayed green rope; groups of branches 1.5-3 cm wide, more or less flabellate, joined laterally and matted basally; filaments dichotomously branched below, becoming irregularly alternate or unilateral above; cells shorter to nearly as wide as long, (100)250-5300 µm from middle to lower axes; short, compound branchlets with recurved apices forming hooks abundant in lower part of thallus, these sometimes becoming rhizoidal and on entangling with other rhizoids producing attachment structure.

Seasonally abundant, saxicolous or occasionally epiphytic, low intertidal, Alaska to San Luis Obispo Co., Calif.; a summer annual in C. Calif. Type locality: N. Calif.

"Codiolum petrocelidis," now known to be a stage in the life history of S. coalita, is described on p. 99.

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 species was transferred to the genus Acrosiphonia (Scagel et al. 1986) because it is multinucleate, while species in Spongomorpha are uninucleate.