Studies on the life history of Syringoderma phinneyi sp. nov. (Phaeophyceae)

Abstract

Click to increase image sizeClick to decrease image sizeThe life history of Syringoderma phinneyi sp. nov. has been studied in culture. The upright thallus as found in the field represents the diploid sporophyte. Meiospores from unilocular sporangia give rise to prostrate microscopic gametophytes which are dioecious and have chromosome numbers of n = 32 ± 2. Gametes are morphologically alike. Zygotes re-establish the diploid sporophytic phase. Unfertilized gametes develop into haploid sporophytes bearing unilocular sporangia. Haploid sporophytes may also develop apogamously from filament cells of gametophytes. This heteromorphic life history contrasts with the isomorphic life histories of Sphacelariales and Dictyotales, the two orders into which Syringoderma has been previously placed.Der Entwicklungsgang von Syringoderma phinneyi wurde an Klonkulturen untersucht. Die im Freiland gefundenen fächerförmigen Thalli stellen den Sporophyten dar. Aus Meiosporen gehen kriechende mikroskopische dioezische Gametophyten hervor. Isogamie führt zum diploiden Sporophyten zurück. Haploide Sporophyten entstehen aus unbrefruchteten Gameten und apogam aus Gametophytenzellen. Syringoderma wurde bisher entweder zu den Dictyotales oder den Sphacelariales gestellt. Die geschilderten Entwicklungsvorgänge passen jedoch nicht zu diesen Zuordnungen.