Rhodymenia ardissonei (Kuntze) Feldmann

Alternative names: Spiky Rose Weed
Description: Thinly fleshy, dark red, flattened fronds, irregularly spreading and semi-peltate, fairly regularly dichotomously branched, to 60 mm long and 5-7 mm broad. One to several fronds arise from a central stipe borne on creeping stoloniferous growths. Tips of fronds reattaching in late summer and autumn and producing new plants in subsequent years giving rise to relatively extensive stands.
Habitat: On silty bedrock or in current-exposed habitats, often associated with foliose bryozoans (above and below), found at (5-) 20-30 m and below (at 5-10 m in Lough Hyne and at Portrush on vertical subtidal cliffs), probably widely distributed, but frequently overlooked or misidentified. Most obvious in deeper water in high-energy habitats, where it may dominate. South-western, western and northern coasts of Ireland and Britain. South to the Mediterranean.
Similar species: Rhodymenia holmesii, Rhodymenia pseudopalmata and Schottera nicaeensis.

Photographs: East of the Skerries, Portrush, Co. Antrim, Ireland; August 2013 © Francis Bunker (In the top photograph Rhodophyllis irvineorum on right middle just above two anemones).