Polyides rotunda (Hudson) Gaillon

Also known as Polyides caprinus (Hudson) Papenfuss.

Description: Cartilaginous, cylindrical, brownish red (drying black) fronds, to 200 mm high, in tufts from basal disc to 10 mm diam. Fronds 1-2 mm thick, undivided for some distance, then regularly and repeatedly dichotomously branched, axils rounded, apices rounded.
Habitat: On rocks and stones in open sandy pools and runnels, lower intertidal and shallow subtidal, widely distributed, common; often in shell sand (above at Finavarra, Co. Clare, Ireland).
Similar species: Furcellaria lumbricalis from which it may be distinguished by the absence of a rhizoidal base, wider branching angles (i.e. more fan-shaped), and that the fronds are red when held up to the light.
Distribution: Sweden and Norway, Britain and Ireland, south to Spain and Morocco; records further south require assessment. In North American from New England north to Nova Scotia.
Note: Polyides is from the Greek (Poly, variable, and -ides, like) and Greek names ending in -ides or -oides are feminine. Polyides was regarded as masculine ("rotundus") but is now regarded as feminine ("rotunda"). Genders of such nouns are correctable under Art. 60 of the Botanical Code. The genus name is less than appropriate as Polyides rotunda populations very similar throughout its range

More pictures are available at AlgaeBase.

Species list