Rhodothamniella floridula (Dillwyn) Feldmann
Also known as Rhodochorton floridulum (Dillwyn) Näegeli; Audouinella floridula (Dillwyn) Woelkerling]
Description: Forming a dense, brown- or purplish-red turf of sparingly branched erect, uniseriate hair-like filaments. Cells oblong, 3-4 times as long as broad. Several plastids, each with a pyrenoid, against cell wall. Reproducing by tetrasporangia, mostly in winter. Monosporangia absent.
Habitat: turf-forming on sand-covered rocks, mid- and lower intertidal, often under Fucus serratus; widely distributed, very common.
Similar species: Rhodochorton purpureum forms less extensive turfs. Microscopic examination for the presence of pyrenoids in the chloroplasts is required to be certain of the identity of Rhodothamniella floridulum.
Key characteristics: Turf-forming habit and association with sand-coved rocks. Absence of monosporangia.