Morphological Variations of the Marine Diatom Genus Actinoptychus in the Coastal Waters of Korea

Abstract

A study on the fine structure of the marine diatom Actinoptychus species has been carried out for taxonomical purposes during the period from January 1983 to October 1992 in the coastal waters of Korea. The present study deals with nine Actinoptychus species, A. adriaticus var. pumila, A. affinis, A. annulatus, A. maculatus, A senarius, A. simbirskiamus, A. splendens A. sp. 1 and A. sp. 2, on the basis of the cell shapes, cell diameters, number of sectors, central hyaline zone and narrow hyaline line or zone, shape and position of the labiate process, areolar shape, and number of areolae and areolations. Among them, only the valve shape of A. annulatus was triangular, but the other six species were disc-shaped. There were variations of the number of sectors at the valve surface showing alternately raised and depressed sectors, except for A. annulatus: 6 sectors in A. senarius, A. simbirskianus, A. sp. 2, 12 sectors in A. adriaticus var. prmila, 14 sectors in A. affinis and A. maculatus, 12-22 sectors in A. splendens and 12-16 sectors in A. sp. 1. There were no differences in the cell diameters of each species compared with previous reports. all species showed a central hyaline zone on the external and internal valve. There was narrow hyaline zone near the valve margin in A. adriaticus var. pumila. A. affinis, A. maculatus, A. splendens except A. senarius. A. splendens showed a hyaline line from the central area to half of the valve margin. Most of exterior areolation was irregular except for A. affinis, but that of the interior was regular.