Citation: Maggs, C.A. & Guiry, M.D. 1982 Morphology, phenology and photoperiodism in Halymenia latifolia Kütz. (Rhodophyta) from Ireland. Botanica Marina 25: 589-599
Number of Pages: 11
Keywords: Alga, Alien, Biogeography, Flora, Galway, Maerl, Marine, Physiology, Seaweed, Sublittoral
Abstract: Halymenia latifolia Crouan frat. in Lloyd ex Kützing (Cryptonemiales, Halymeniaceae), a marine red alga originally described from the Brittany coast, has been positively identified for the first time in the British Isles, growing in the subtidal at two sites in Galway Bay, western Ireland. Plants grow only on dead maerl (unattached coralline algae) and shell fragments. Acrochaetioid filaments form the basal holdfast and these penetrate into the calcareous substrata, giving rise to upright fronds. Plants become apparent in April in Galway Bay as small upright fronds, start to reproduce in August/September, and reach their maximum size in December, at which time they start to degenerate. Details of the reproduction of field-collected material are given which correspond well previously-published descriptions of the reproductive structures of other Halymenia species. Carpospores isolated into laboratory culture produce plants with a normal morphology when grown on shells but not when grown on glass slides.