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LIFE HISTORY AND SYSTEMATIC POSITION OF PSEUDOCHORDA GRACILIS SP. NOV. (LAMINARIALES, PHAEOPHYCEAE) 1
Author(s) -
Kawai Hiroshi,
Nabata Shinichi
Publication year - 1990
Publication title -
journal of phycology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.85
H-Index - 127
eISSN - 1529-8817
pISSN - 0022-3646
DOI - 10.1111/j.0022-3646.1990.00721.x
Subject(s) - biology , thallus , sporophyte , holdfast , sporangium , botany , gametophyte , algae , pollen , spore
Pseudochorda gracilis sp. Nov. (Pseudochordacease, Laminariales) is described from the Japan Sea coast of Hokkaido/ the species is subtidal, epilithic and annual, appearing in spring and maturing in winter. Erect thalli grow solitary or in tufts on a small discoid holdfast. They are simple, cord‐shaped and hollow, with inner hyphal filaments, cylindrical medullary cells and paraphyses consisting of 3–6 cells. Hair tufts are observed only in young thalli. Unilocular sporangia are sessile and narrowly ovate. In culture, P. gracilis shows a heteromorphic life history with oogamy, characteristic of the order Laminariales. Gametophytes are dioecious and dimorphic. Gametophytes mature under lower temperature conditions (usually below 10°C), and sporophytes mature under low temperature and short‐day conditions (5°C, SD). The seasonal growth pattern of the species results from the photoperiod‐temperature conditions controlling saprophyte maturation.