Studies on Kuckuckia spinosa (Fucophyceae, Sorocarpaceae): life history, temperature gradient experiments, and synonymy

Kuckuckia spinosa and Kuckuckia kylinii are distinguished mainly by the presence of basally sheathed true hairs in the latter. However, culture studies have shown that the sheath is an ephemeral structure as it splits, breaks off, and the basal remnant disintegrates and disappears eventually. Therefore, Kuckuckia kylinii gradually develops into Kuckuckia spinosa , also with regard to filament diameter. Consequently, the two species are merged with priority to K. spinosa. The life history is of the direct type as the swarmers from the plurilocular sporangia develop by immediate differentiation into plants similar to the mother plant. It has been confirmed experimentally that this species belongs to the warm temperate Mediterranean-Atlantic group with a southern reproductive boundary close to 25°C and a northern reproductive boundary close to the 10°C summer isotherms. This is the first report of this species from the Canary Islands.