Morphology and life history of Halopteris filicina (Sphacelariales, Phaeophyceae) from Korea

Abstract

SUMMARY The vegetative morphology and life history of Halopteris filicina (Grateloup) Kutzing, collected from Korea, were examined in laboratory culture. Field plants attaining 3–5 cm in height were epilithic, tufted, yellowish‐brown, and produced numerous erect axes with alternately distichous branches from compact basal discs. They were cultured under a 12:12 h LD photoperiod at 10°‐C, 15°C and 20°C to observe the influence of temperature on reproduction. At 10°C plants grew only vegetatively, whereas at 15°C and 20°C they produced unilocular sporangia. Unispores released from sporangia developed into monoecious, anisogamous gametophytes that formed plurilocular female and male gametangia on the same lateral branches. The zygotes, by fusion of female macrogametes and male microgametes, developed into sporophytes bearing unilocular sporangia, whereas the unfused female gametes germinated parthenogenetically. This species was confirmed to have an isomorphic life history, basically similar to the other species of Sphacelariales.

Life history of Japanese Stypocaulon durum (Sphacelariales, Phaeophyceae)

“…These results are fully in accordance with an isomorphic diplohaplontic life history, which seems to be usual in Sphacelariales (Prud'homme van Reine 1982). In H. filicina, sexual reproduction is by anisogamy, whereas in other genera isogamy and oogamy are also assumed to occur, although complete observations, like those by van den Hoek and Flinterman (1968) and by Keum et al (1995) are often still lacking. Our observations on occurrence of plurilocular sporangial structures in S. durum do not change this general picture.…”

“…The family Stypocaulaceae Oltmanns currently includes five genera (Alethocladus Sauvageau, Halopteris Kü tzing, Phloiocaulon Geyler, Ptilopogon Reinke and Stypocaulon Kü tzing, Prud'homme van Reine 1993). Among them, the life history in culture has been studied only in a few taxa (Moore 1951;Ernst-Schwarzenbach 1957;Prud'homme van Reine 1982, 1991, 1993Keum et al 1995). No sexual reproductive structures have been reported in many species and in some species even neither asexual nor sexual sporangia/ gametangia have been described so far.…”

“…in Prud'homme van Reine 1993). In Halopteris, among the four species recognized in Prud'homme van Reine (1993) (Sauvageau 1903;Ernst-Schwarzenbach 1957;Keum et al 1995). In cultures of H. filicina Ernst-Schwarzenbach (1957) observed apomictic development of plurilocular sporangia with small loculi (microgametes) as well as of plurilocular sporangia with larger loculi (macrogametes).…”

“…Often, however, the spores from plurilocular sporangia of both sizes did not release and apomictic development occurred within the plurilocular sporangia. Keum et al (1995), however, observed in situ conjugation between plurizoids of different sizes (evidently female and male gametes) released from a plant in culture. The macrogametes were observed to Life history of Stypocaulon durum settle earlier than the microgametes, while macrogametes that did not fuse with microgametes always developed parthenogenetically into haploid germlings.…”

“…The macrogametes were observed to Life history of Stypocaulon durum settle earlier than the microgametes, while macrogametes that did not fuse with microgametes always developed parthenogenetically into haploid germlings. Keum et al (1995) counted 16 chromosomes in mitotically dividing nuclei of unilocular sporangia as well as in gametophytes and in haploid germlings. These results are fully in accordance with an isomorphic diplohaplontic life history, which seems to be usual in Sphacelariales (Prud'homme van Reine 1982).…”