Rhizoclonium riparium

Rhizoclonium riparium (Roth) Harvey var. riparium

Conferva riparia Roth, 1806:216; Koster, 1955:336, fig. 1.

Rhizoclonium riparium (Roth) Harvey, 1849:238, pl. CCXXXVIII; Setchell and Gardner, 1920b:182; Smith, 1944:63, pl. 7: fig. 4; Taylor, 1945:55; Doty, 1947:27; Hollenberg, 1948:155; Dawson, 1961b:376; Scagel, 1966:74, fig. 18A–F; Nienhuis, 1975:84–88, figs. 35–60; Abbott and Hollenberg, 1976:92, fig. 46; Zedler, 1980:124; Nienhuis and de Bree, 1981:434; R. Aguilar-Rosas, 1982:84; Zedler, 1982:41; Schnetter and Bula Meyer, 1982:18, pl. 1: figs. Q–S, pl. 2: figs. A, B; Blair, 1983:203; Huerta-Múzquiz and Mendoza-González, 1985:42; Mendoza-González and Mateo-Cid, 1986:419; Mateo-Cid and Mendoza-González, 1991:27; Stewart, 1991:32; Mateo-Cid and Mendoza-González, 1992:25; León-Tejera et al., 1993:199; Servière-Zaragoza et al., 1993:482; Mateo-Cid and Mendoza-González, 1994b:44; Mendoza-González et al., 1994:112; Pedroche et al., 1995:112; González-González et al., 1996:289; Mendoza-González and Mateo-Cid, 1996:76, 88, pl. 27: fig. 122; Sánchez-Lizaso and Riosmena-Rodríguez, 1997:56; Núñez-López et al., 1998:39; L. Aguilar-Rosas et al., 2000:133; Paul-Chávez and Riosmena-Rodríguez, 2000:146; Cruz-Ayala et al., 2001:190; Abbott and Huisman, 2004:83, fig. 25D; Wysor, 2004:218; Pedroche et al., 2005:50; Hernández-Herrera et al., 2005:146; Dreckmann et al., 2006:154.

Algae unbranched, uniseriate filaments of cylindrical cells, mostly 1–2 times longer than wide (sometimes up to 6 times); (10–)15–30(–45) µm in diameter by 15–90(–270) µm long; without or with a few short rhizoidal proliferations of 2–5 (or more) cells; often unattached. Chloroplast reticulate, with 6 or more pyrenoids.

Vegetative reproduction by fragmentation. Reproduction not reported in Gulf specimens. Reproduction has been reported in Europe. Asexual reproduction is by biflagellate and quadriflagellate zoospores, and sexual reproduction by isogamous gametes (Nienhuis, 1975).

HABITAT. Entangled with other algae or aquatic plants, in tide pools, or on sand flats and mudflats of salt marshes, lagoons, and estuaries; or free-floating and unattached (also reported as epiphytic on Gelidium johnstonii and Spyridia filamentosa; L. Aguilar-Rosas et al., 2000); high to low intertidal.

DISTRIBUTION. Gulf of California: Puertecitos to Punta Arena (north of Cabo Pulmo). Pacific coast: Alaska to Chiapas; Panama; Colombia; Galápagos Islands; Chile; Hawaiian Islands; China; Japan.

TYPE LOCALITY. Norderney, East Frisian Islands, Germany.