Abstract
Resting stage cells of six diatom species, Actinoptychus senarius, Biddulphia alternans, Lithodesmium variabile, Odontella longicruris, O. mobiliensis, and Detonula pumila were newly identified from bottom sediments of Ago Bay, central Japan. The resting stage cells of A. senarius, B. alternans and L. variabile are very similar in morphology to their vegetative cells; hence, these resting stage cells are “resting cells”. The resting stage cells of O. longicruris and O. mobiliensis closely resemble the vegetative cells in morphology, therefore, they are regarded as resting cells. However, they have some morphological differences compared with the vegetative cells, indicating a possibility of them being resting spores. The resting stage cells of D. pumila are quite different in morphology from the vegetative cells; therefore, these are “resting spores”. The morphology of the resting spore of D. pumila is circular in valve view. In girdle view, each valve shows the same shape, slightly vaulted, and has a distinct mantle. As a common feature of the resting stage cells of the six species, the plastids show a darker color than those of vegetative cells, and are positioned unevenly in the cells.
