UC specimens and range limits for Dictyoneurum reticulatum

• 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: Ranging from northern Vancouver Island, British Columbia, Canada (see Pacific Northwest Herbaria map) to La Jolla, San Diego Co.

Status: Recent molecular and developmental studies have shown that there are indeed two species in the genus (H. Kawai, pers. comm.). There is a continuum of forms so that it is sometimes difficult to distinguish the two species in the field.

Habitat: In more or less sheltered environments, from low intertidal to deep subtidal; deeper in the southern end of its range

Life History: Alternation of heteromorphic phases (large diploid sporophyte and microscopic haploid dioecious gametophytes)

Search Sequences in GenBank

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

Dictyoneuropsis Smith 1942

Sporangial thalli perennial, at first with unbranched prostrate stipe, the anterior end bending upward and terminating in single blade. Decumbent portion of stipe flattened and with branched haptera along lateral margins. Blades sublinear, with midrib; surface of blade, except for midrib, with coarse reticulum of narrow ridges. Blade and erect portion of stipe splitting longitudinally with age to form forked stipe, each branch terminating in a blade, the process repeated until stipe becomes 3 or more times dichotomous. Longitudinal division of blade through midrib followed by regeneration of new half blade along exposed edge of midrib. Sporangia in irregularly shaped sori between reticulations of blade. Sori at times covering midrib.

Dictyoneuropsis reticulata (Saund.) Smith

Costaria reticulum Saunders 1895: 58. Dictyoneuropsis reticulata (Saund.) Smith 1942: 651; 1944: 140.

Thalli to 95 cm tall, yellowish-brown; prostrate portion of stipe to 3 times dichotomous, the dichotomies 4-6 mm broad, 1 mm thick; haptera along lateral margins of dichotomies, finely divided, fibrous, 3-5 times dichotomous, 25-30 mm long; mature blades linear, slightly narrower at upper end, broadly rounded at base; reticulation of blade restricted to portions lateral to midrib, but entire blade at times bullate; maximum breadth of blade 15-25 cm.

Infrequent in sheltered areas, saxicolous, low intertidal (to 20 m), Vancouver I., Br. Columbia, to N. Channel Is., Calif.; common in vicinity of type locality, Monterey Bay near Pacific Grove, 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: On the basis of sequences of the nuclear marker ITS, Lane et al (2006) merged Dictyoneuropsis reticulata with Dictyoneurum californicum, as did Setchell and Gardner (as Costaria reticulata, 1925). However, Silva (in Pedroche et al. 2008) disagreed, and transferred Dictyoneuropsis reticulata to Dictyoneurum. Blades tend to be narrow in more exposed environments.