Reproduction and life history of meredithia microphylla (J. ag.) j. ag. (kallymeniaceae, rhodophyta) from ireland
Authors: Guiry, M.D. and Maggs, C.A.
Journal: Giornale Botanico Italiano
Volume: 118
Issue: 3-4
Pages: 105-125
ISSN: 0017-0070
DOI: 10.1080/11263508409426665
Abstract:Meredithia microphylla (= Kallymenia microphylla) is found on subtidal rock overhangs in the north-eastern Atlantic and in the Mediterranean. Rigid, semi-peltate, auriculate blades are formed sympodially on a branched, terete stipe. An account of the morphology of male and female reproductive organs is given for the first time from field material. Carpospores gave rise in culture to prostrate plants which formed tetrasporangia at daylengths of, or less than, 12 h at 15°C, but not at 10, 18 or 20oC, 8:1̅6̅ h, and only in 5% normal strength enriched seawater media. Tetrasporogenesis was completely inhibited by a night break regime of 8:7.5:1̅:7.5̅ h, at 15”C, showing that the response is photoperiodic. Tetrasporangia were formed terminally in a mucilaginous sorus and were regularly or irregularly zonately cleaved. Tetraspores from cultured plants initially gave rise to prostrate growths similar to those obtained from carpospores. These formed erect blades at 15°C, 16:8 h, and 15oC, 8:16̅ h, although formation was much more rapid under the short-day regime. The blades grew in culture in a similar manner to field plants, but did not form reproductive structures, despite being subjected to a wide range of temperature and daylength conditions over a period of 3 years. The genus Meredithia, which had been merged with Kallymenia by several authors, should be reinstated to include only M. microphylla. Characters such as the formation of cartilaginous, semi-peltate blades with a dense medullary structure on a terete, branched stipe, and the development of zonately-divided tetrasporangia in a sorus on a prostrate phase, serve adequately to distinguish this genus from other Kallymeniaceae. © Taylor & Francis Group, LLC.
Source: Scopus