This species forms thin filmy blades, 2-7 cm tall, dark to purplish or olive red, typically gregarious on species of kelp (Image A). Mid thallus the cells are irregular in outline, angular, separated by relatively thick walls, and only 5-16.5 µm in dimensions (Image B). Toward the margins vegetative cells become more regularly rectangular or cuboidal in outline (Image C). Mid thallus vegetative cells in section are cuboidal to rectangular with the thalli only 24-29 µm thick (Image D), while the margins have a rounded outer cell (Image D). Despite the material used for microscopy being fixed in formaldehyde, chloroplast details were still evident – a single stellate structure with a central pyrenoid (Image C). Along the margin at the top of the blade reproductive packets form (Image E), with spermatangial packets evident in transverse section of our fixed specimen (Image F).
We have collections from throughout BC, typically growing on kelp, but also a Desmarestia sp., as well as one collection from Santa Cruz, CA, recorded as growing on rock in a sandy area. They range from the low intertidal to subtidal (13 m) and are particularly common on Laminaria setchellii Silva in the BC flora, but also Egregia menziesii (Turner) Areschoug.
There is some uncertainty as to the status of Porphyrella as a genus (Sutherland et al. 2011) distinct from Pyropia (Yang et al. 2020). If synonymy is in order the correct name would be Pyropia gardneri (G.M.Smith & Hollenberg) S.C.Lindstrom.
Image A. Blades growing on the margins of Laminaria setchellii Silva in the shallow subtidal (2 m) at Murchison I. NE site, Plot 1 (2-5 ft), Gwaii Haanas, BC (EGWS001468).
Image B. Surface view mid thallus of a vegetative region of a blade (subtidal (2 m) on Laminaria setchellii Silva, Arnold Pt. (east side, left transects), Gwaii Hannas, BC; GWS048419, formaldehyde fixed).
Image C. Surface view near the margin of a vegetative blade, note the stellate chloroplasts with a central pyrenoid (GWS048419, formaldehyde fixed).
Image D. Vegetative section mid thallus (GWS048419, formaldehyde fixed, aniline blue stained).
Image E. Vegetative section at the margin (GWS048419, formaldehyde fixed, aniline blue stained).
Image F. Developing reproductive packets in surface view (GWS048419, formaldehyde fixed).
Image G. Mature(?) spermatangial packet (arrow) (GWS048419, formaldehyde fixed, aniline blue stained).
Seaweed of Canada 