Morphology, Phenology and Photoperiodism in Halymenia latifolia Kiitz. (Rhodophyta) from Ireland
Authors: Maggs, C.A. and Guiry, M.D.
Journal: Botanica Marina
Volume: 25
Issue: 12
Pages: 589-600
eISSN: 1437-4323
ISSN: 0006-8055
DOI: 10.1515/botm.1982.25.12.589
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 substrates, 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 with 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. Tetrasporangia are formed on the resulting upright fronds in both 16:8h (LD) and 8:16h (SD) photoregimes at 15 °C but the number of tetrasporangia formed at SD is significantly greater than at LD. Nightbreaks (8:7.5:1:7.5h photoregime) at 15 °C are effective in reducing to control LD levels the numbers of tetrasporangia formed. It is concluded therefore that a true, although not absolute, photoperiodic response is involved in tetrasporogenesis in this species. Day-lengths of 20 h completely inhibited tetrasporangial initiation. Some tetrasporangia were formed at 10 °C, 8:16h but not at 10 °C, 16:8h. Tetraspores from laboratory-cultured plants give rise to plants bearing both carpogonial and auxiliary ampullae at 15 °C, 8:16h. Monosporangia are not found in any phase of the life history, which appears to be of the Polysiphonia-type. © 1982, IEEE. All rights reserved.
Source: Scopus
MORPHOLOGY, PHENOLOGY AND PHOTOPERIODISM IN HALYMENIA-LATIFOLIA KUTZ (RHODOPHYTA) FROM IRELAND
Authors: MAGGS, C.A. and GUIRY, M.D.
Journal: BOTANICA MARINA
Volume: 25
Issue: 12
Pages: 589-599
ISSN: 0006-8055
DOI: 10.1515/botm.1982.25.12.589
Source: Web of Science (Lite)