UC specimens and range limits for Pelagophycus porra

• 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: Yellow Banks, Santa Cruz Island (34.010299, -119.544717) to Punta Abreojos, Baja California, Mexico (26.700000, -113.583000) (Pedroche et al. 2008). Specimens north of Point Conception represent drifted individuals.

Status: This species is easy to identify.

Habitat: Growing on rock in windward populations; leeward populations grow in sand habitats, attached to worm tubes, pebbles and shells.

Life History: Alternation of heteromorphic phases (large diploid sporophyte and microscopic haploid dioecious gametophytes). Sporophytes annual or perennial, to 3+ years old. Juveniles with large oval blade, very thin.

Associated Taxa: Laminaria farlowii, Agarum fimbriatum, Chaetopterus variopedatus

Search Sequences in GenBank

Pelagophycus Areschoug 1881

Sporangial thalli with holdfast of widely spreading, frequently branched, slender haptera, the ultimate branchlets fine (often 1 mm diameter). Haptera produced in irregular whorls at junction of lower stipe and holdfast. Stipe solid and cylindrical throughout much of length, the upper portion inflated into stiff, elongate apophysis, this sharply constricted near distal end and terminating in ellipsoid to spherical pneumatocyst. Blades borne singly at ends of a system of sympodial branches ("antlers"), these arising from short, thick stalk at top of pneumatocyst. Mature blades to 1 m broad, markedly bullate, with short superficial spines. Sori in irregular patches on blades.

Pelagophycus porra (Lem.) Setch.

Laminaria porra Leman 1822: 189. Pelagophycus porra (Lem.) Setchell 1908b: 134; Setchell & Gardner 1925: 630. Nereocystis gigantea Areschoug 1876: 71. P. giganteus (Aresch.) Aresch. 1881: 49. P. intermedius Parker & Bleck 1965: 61.

Large, distinctive thalli with "antlers" formed from branches, these suggesting the common name "elk kelp", the plants further distinguished from Nereocystis by the large, corrugated blades adorned by spines. Sporangial thalli with haptera confined to short length of lowermost stipe, usually spreading 10-40 cm, often attached to rock and spreading into sand and shells; stipe variable in length, 7-27 m long, terminated by tubular apophysis and spherical to ellipsoid pneumatocyst, this 10-20 cm diam.; flattened branches arising from top of pneumatocyst and branching dichotomously after 1-4 cm in single plane, forming 2 sympodial members, each branch bearing single blade; blades on mature sporophytes 6-20 m long, to 1 m broad, slightly undulate, coarsely bullate, the convex surfaces of bullations on both sides of blades usually bearing spines, these curving distally and 1-3 mm long; margins of blades with short, spiny protuberances; sori in scattered, irregular patches on blades. Populations scattered, subtidal on rock in gravel, Pt. Conception, Calif., to Is. San Benito, Baja Calif.; sporophytes in 30-90 m depth usually of uniform size. Drifted specimens recorded from Tomales Bay (Marin Co.), Pacific Grove, and near Pismo Beach, Calif., and from Pta. San José, Baja Calif. Type locality: near Santa Catalina I., Calif.

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: Pelagophycus was collected by LeGentil on his voyage to the Indies; Leman records the site as "dans la mer du Sud", referring to the Pacific Ocean. LeGentil, in his report on expeditions in the Indian Ocean to observe the transit of Venus, provided a figure based on a drawing by Father Don Estevan Roxas y Melo. Leman described Laminaria porra based on this drawing of drift material. Areschoug used plants from Santa Catalina Island, collected by Eisen, as the basis for his description of Nereocystis gigantea, which he later transferred to Pelagophycus. This description fits the morph that occurs on the leeward sides of San Clemente and Santa Catalina islands and is illustrated in Abbott & Hollenberg, p. 252. The leeward morph has a shorter stipe, fewer blades and is annual. The windward morph occurs on the windward coasts of San Clemente Island, Santa Cruz Island, mainland southern California and Baja California, Mexico. The windward morph is much larger, with more blades, bigger pneumatocyst and longer stipe, and is a short-lived perennial (Miller & Dorr 1994). These morphs are genetically based (Miller et al. 2000), and may be considered incipient species -- in the process of isolation.