Codium dawsonii P.C. Silva, F.F. Pedroche, M.E. Chacana et K.A. Miller

Codium dawsonii P.C. Silva, F.F. Pedroche, M.E. Chacana et K.A. Miller ( Figures 3 View Figure 3 and 4 View Figure 4 )

Thallus erect, profusely branched to 10 orders, delicate ( Figure 3 View Figure 3 ). Branching usually dichotomous or subdichotomous, but often irregular, giving monopodial aspect to thallus. Branches cylindrical to compressed, especially at the dichotomies and apices, 4 (–5) mm diameter at base, 1.5– 2 mm diameter distally, to 13 (–20) cm high. Thallus attached to substrate (rocks or shells) by discoid holdfast. Color olive green to grass green. Thallus dissecting out into individual utricles. Utricles claviform or campanulate, slightly constricted below the apex, (69–) 100–170 (–200) µm diameter, (370–) 400–500 (–580) µm long in upper portion of thallus, (40–) 60–90 (–110) µm diameter basally. Apices of utricles truncate or rounded, apical wall slightly thickened (to 13 µm thick). Hairs or hair scars borne in zone 45–100 µm below apex of utricle. Medullary filaments 20–30 µm diameter ( Figure 4 View Figure 4 ). Gametangia lanceolate or fusiform, (58–) 62–75 (–85) µm diameter, (140–) 160–190 (–210) µm long, borne singly on short pedicel in zone 200–300 µm below apex of utricle.

Holotype: Mosquito Cove, San Clemente Island, California, on shallow boulders and reefs with dense algal cover, 6–9 m depth, K. A. Miller SC V-012-88, 22.v.1988 ( UC 1718035 ) ( Figure 3 View Figure 3 ).

Specimens examined (north to south)

Channel Islands, California

Santa Cruz Island: UC1612968, UC1574488, UC1574797, UC1574793, UC1996200. Anacapa Island: UC1996201. Santa Barbara Island: UC1574796, UC1718036, UC1996198, UC1996199, UC1996197. Santa Catalina Island: UC1574794, UC1819304, UC1985389, UC1883562, UC1819309, UC1985388, UC1985390; UC1985392, UC1985391, UC1883561, UC1996193. San Clemente Island: UC1574789, UC1717994, UC1996196, UC1996195.

Baja California, Mexico (insular)

Islas Los Coronados: UC1965988, UC1574387. Isla Guadalupe: UC1818855, UC1818854, UC1818857, UC1718031.

Baja California, Mexico (mainland)

Ten miles west of Punta Malarrimo, Bahía Viscaino: UC1918822.

Previous records: as Codium dawsonii Silva ined. in Goff et al. (1992: 1280); Schmieder (1996: 235); as C. dawsonii Silva, Pedroche et Chacana ined. in Pedroche et al. (2002: 49, figs. 59, 60), Pedroche et al. (2005: 71).

Following a preliminary study of C. dawsonii from Isla UC1735228, UC1935031, UC1935033, UC1823617. San Clem- Guadalupe, Silva (1951) published a monograph of the ente Island: UC1953502. Codium of California, but failed to recognize the presence San Diego County: UC1953501, UC1953498, UC1953497. of C. dawsonii in the Channel Islands. Instead, he assigned a collection from Santa Cruz Island and one from Santa Catalina Island to Codium cuneatum Setchell et Gardner Baja California (insular) (1924) a species originally described from the Gulf of Cali- Islas Los Coronados: UC1831528, UC1604008, UC1831529, fornia that was merged with Codium simulans Setchell et UC 1604010. Islas Guadalupe: UC1716828, UC1718017. Gardner (1924) by Pedroche (1998). Silva included in C. Rocas Alijos: UC1946214, UC1946215. cuneatum a disparate array of specimens from southern California and northern Baja California. In the 1980s, Kathy Ann Miller began making sublitto- Baja California (mainland)

ral surveys of the Channel Islands and discovered that C. Tres Hermanas, Bahía de Todos Santos: growing on rocks dawsonii grows abundantly and luxuriantly in the south- in intertidal zone, R. Aguilar-Rosas s.n., 30.x.1982, CMMEX ern Channel Islands at depths of 9– 12 m. In an attempt 1000, 2005. Campito, 19 km east of Punta San Eugenio, to determine whether the Gulf species, C. simulans (= C. Bahía Vizcaino: UC1831470. Bahía Asunción: UC1604007. cuneatum ), occurs in California, Miller provided material This species is one of several adherent forms distinfrom the type specimens of all species described by Setch- guished from one another by anatomical characters that ell and Gardner (1924) from the Gulf of California to Jeffrey may seem trivial to the nonspecialist. The differences are, R. Hughey. On the basis of comparison of nucleotide in fact, sufficiently large to suggest that these species consequences obtained from these specimens, he concluded stitute a distinct phylogenetic group. On the Pacific coast (pers. comm.) that C. dawsonii is distinct from all species of North America, the only adherent species other than of Codium described from the Gulf of California by Setch- Codium hubbsii is Codium setchellii Gardner (1919: 489 , ell and Gardner (1924). pl. 42: figs. 10, 11; type locality Pacific Grove, California), Codium dawsonii can be distinguished from Codium which is readily distinguished by the lack of hairs or hair fragile subsp. californium C. Maggs et J. Kelly by its scars and by the smooth, unornamented apical walls of lighter color, shorter internodes, and numerous orders of the utricles. In contrast, utricles of C. hubbsii frequently branching. The compressed dichotomies and apices are bear hairs and have apical walls that are usually at least diagnostic. slightly alveolate.

On the mainland of California, C. setchellii usually grows on the sides of boulders partly buried in sand, in the lowest intertidal zone. The thallus forms a tightly

Codium hubbsii E.Y. Dawson

adherent carpet that spreads out in all directions. The advent of SCUBA, however, has led to the discovery of a

Codium hubbsii E.Y. Dawson 1950: 151 , fig. 14. Silva, 1951:

subtidal adherent Codium View in CoL that is anatomically indistin-

85, pl. 1, text-figs. 3, 6–9. Dawson et al. 1960a: 26. Dawson

guishable from the intertidal form. According to Dawson

et al. 1960b: 5–12. Silva et al. 1996: 235. Pedroche et al.

et al. (1960a,b), C. hubbsii and C. setchellii are common

2002: 20, figs. 7–14. Pedroche et al. 2005: 74.

inhabitants of kelp beds in Baja California at depths of

9–23 m, where they have the same habit and habitat and are macroscopically indistinguishable.

Holotype

Whereas C. setchellii survives cold water as far north as Sitka, Alaska, and thrives in upwelling areas in Baja

Islas San Benito, Baja California: Hubbs46-205, 18.viii.1946

California as far south as Punta Baja ( Dawson 1953: 109),

( AHFH 36930 in UC).

C. hubbsii requires a higher optimal temperature. It occurs as far north as the southern Channel Islands of California, proceeding southward through the Mexican coastal

Specimens examined (from north to south) islands and thence along the coast of Baja California Sur as far as Punta Abreojos. At Isla Guadalupe, C. hubbsii

Channel Islands, California grows both intertidally and subtidally (to depths of 25 m). Santa Cruz Island: UC 1819291. Santa Barbara Island: The attribution of C. setchellii to Isla Guadalupe, Isla UC 1823623. Santa Catalina Island: UC 1819289, UC 1823612, Asunción, and other localities south of Punta Baja by Pedroche (1998) and Pedroche et al. (2002, 2005) is based on a misidentification of C. hubbsii .