Blades up to 20 cm in height; oval to oblong to highly variable in outline; olive-purplish to deep red (Image A). Reproductive plants display a distinct division of the blade into male and female sectors (Image B). In surface view of vegetative regions of the blade the cells are angular, 12-32 µm in dimensions, and show the distinct stellate chloroplast with a central pyrenoid (Image C). In section vegetative blades are 55-65 μm wide and consist of two rows of typically round to slightly oval cells with the chloroplast appressed against the outer cell wall (Image D). Surface view of the ‘zipper’ reveals the clear demarcation between the female and male cells of the blade sectors (Image E). This species is clearly sexual as some sections reveal spermatangia attached to the female region of the blade with fertilization tubes extending to the carpogonia (female reproductive structures, essentially eggs; Image F). Transverse section of a mature region of the male blade, 65-70 μm wide, reveals two distinct layers of spermatangial packets (Image G).
We have multiple records for this species extending from mid intertidal pools to subtidal (6 m), and from northern Labrador to ME, although it is reported to extend south of Cape Cod (Mathieson & Dawes 2017). It is typically an epiphyte on a variety of algal species, notably Corallina officinalis Linnaeus, Dumontia contorta (Gmelin) Ruprecht, and Mastocarpus stellatus (Stackhouse) Guiry, although it is common on fucoids and kelp and can can also grow on rock and other hard substrata. Reportedly an aseasonal annual, our predominantly Atlantic Canada collections span March through September. This species is easily distinguished from its congener Wildemania amplissima (Kjellman) Foslie, which has the male and female packets intermixed rather than sectored. An additional species, Wildemania tenuissima (Strömfelt) De Toni, is recognized in the NW Atlantic by Mathieson & Dawes (2017), but to date we have not recovered genetically distinct records assignable to this species in this flora.
Image A. Specimen growing on Corallina officinalis Linnaeus in the low intertidal at Lepreau Exposed site #2 (Tim’s Point), Bay of Fundy, NB (GWS047001).
Image B. Specimen spread out to reveal the sectoring of the blade into male (top, pale) and female (bottom, red) sectors (subtidal (6 m) on algae, Paddys Head, NS; GWS011871).
Image C. Surface view of vegetative region of blade (GWS047001).
Image D. Transverse section of vegetative region of blade (GWS047001).
Image E. Surface view at the line (zipper) between male and female sectors (GWS047001).
Image F. Section of an early postfertilization region of the blade with the spermatangia on the blade surface and fertilization tubes (arrows) extending through the cell walls to the carpogonia (low intertidal on Corallina officinalis Linnaeus, Wallace Cove Lighthouse, NB; GWS045957).
Image G. Transverse section of male region of blade revealing two layers of mature spermatangial packets (GWS047001).