UC specimens and range limits for Acrosorium ciliolatum

• 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: A distinctly southern species, most common from Santa Catalina Island south through Baja California, Mexico, but occasional north to Santa Barbara County, including the Channel Islands (except San Miguel). Absent in the Gulf of California. Disjunct; northern limit in Monterey Bay, where it is subtidal; also reported from the drift in San Luis Obisbo County and collected in the low intertidal and subtidal at Diablo Canyon. Both of these areas, north of Point Conception, are warm-water pockets.

Status: This species needs re-evaluation in California. Reported as [Acrosorium uncinatum] (Turner) Kylin in [MAC], a species with British type locality, it is now called [Acrosorium ciliolatum] (Harvey) Kylin, based on the type [Nitophyllum ciliolatum] Harvey 1855 from Western Australia (Womersley 2003). [Acrosorium venulosum] (Zanardini) Kylin is a synonym. Molecular studies are needed to confirm this identification.

Habitat: Seagrass beds, kelp forests, tube worm populations

Life History: Triphasic, though gametophytes are extremely rare and tetrasporophytes uncommon; vegetative reproduction by fragmentation.

Search Sequences in GenBank

Acrosorium Zanardini 1869

Thalli epiphytic or saxicolous, mostly small, entangled, flattened, with irregularly branched, ribbonlike blades 1 cell thick except in lower portions; with marginal initials. Macroscopic veins lacking, microscopic veins present. Tetrasporangia in 1 large sorus at each branch apex. Spermatangia in oval sori. Cystocarps distributed over thallus, with terminal carposporangia.

Acrosorium uncinatum (Turn.) Kyl.

Fucus laceratus var. uncinatus Turner 1808: 153. Acrosorium uncinatum (Turn.) Kylin 1924: 78; Dawson 1962: 94.

Thalli epiphytic or saxicolous, to 8 cm tall, deep rose red; erect portions of narrow blades 2-20 mm wide, the blades irregularly toothed, occasionally ending in hooks often functioning as tendrils; saxicolous thalli more robustly developed but shorter than epiphytic ones; rarely fertile in California, only the tetrasporangia seen.

Rare in north, subtidal (10-30 m) on worm tubes or rocks at Monterey Peninsula, and low intertidal to subtidal (to 30 m), commonly epiphytic on a variety of algae, especially Pterocladia, from San Luis Obispo Co., Calif., to Bahia San Lucas and Is. San Benito, Mexico, including Channel Is., Calif., and I. Guadalupe, Baja Calif. Type locality: England.

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