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Taxonomic study of the genus Spongomorpha (Acrosiphoniales, Chlorophyta) in Japan. I. Spongomorpha spiralis *
Author(s) -
Miyaji Kazuyuki
Publication year - 1996
Publication title -
phycological research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.438
H-Index - 44
eISSN - 1440-1835
pISSN - 1322-0829
DOI - 10.1111/j.1440-1835.1996.tb00035.x
Subject(s) - biology , thallus , gametophyte , botany , sporophyte , sexual reproduction , ploidy , multinucleate , type locality , genus , pyrenoid , chloroplast , pollen , biochemistry , gene
SUMMARY The morphology, life history, and the geographical distribution of Spongomorpha spiralis Sakai in Hokkaido, Japan, was studied. The thallus is characterized by its digitate tufts (bundles) of slender filaments with hooked branchlets. The diameter of the filaments is usually 20‐50 μm in the basal portion, 50‐130 (70‐110) μm in the middle portion of main axes, and 30‐150 μm in the upper portion. The diameter of the middle portion of the main axes varies from locality to locality. At Muroran, for example, the range is 70‐130 μm (average approximately 100 μm), while at other localities it is 50–100 μm (average approximately 70 μm). The diameter of filaments in the upper portion decreases toward the end of the growing season. The cells are multinucleate with four chromosomes in each nucleus of the haploid plant. The manner of cell division is identical to the process reported previously for the Spongomorpha‐Acrosiphonia complex. Sexual reproduction is isogamous with anteriorly biflagellate gametes. Plants are unisexual. The life history involves an alternation of heteromorphic generations: the gametophytic phase is a macroscopic, filamentous thallus and the sporophytic phase is a microscopic, ellipsoidal or club‐shaped cell. Optimal culture condition for growth and reproduction of both stages was 5°C and long daylength. The gametophyte developed abnormally at 15°C. The sporophyte developed normally at 15°C, but did not produce zoospores.