CELL DIVISION PATTERNS AND DIURNAL CYCLE OF <em>PORPHYRA ABBOTTAE</em> (RHODOPHYTA, BANGIALES) CARPOGNIAL AND CARPOSPORE DEVELOPMENT.

Post-fertilization development of carpospores in Porphyra is a well-documented phenomenon. Development of the pre-fertilization carpogonial cells from vegetative cells, however, has not been previously described. In Porphyra abbottae Krishn., a rocky intertidal monostromatic species occurring from British Columbia to central California, large cells designated here as &quot;procarpogonial mother cells&quot; (PMCs), initiated the formation of the carpogonial cells. The PMCs formed during late night mitoses beginning at 0200 h with cytokinesis form 0300-0500 h during short day periods of 10:14 h LD in northern California (38&#176;20&#39; N, 123&#176;03&#39; W and 36&#176;37&#39; N 121&#176;55&#39; W). The PMC cut off numerous smaller cells which in turn divided equally. Approximately 12 h later, at 1500 h (day 1) the smaller cells were recognizable as carpogonial cells by the presence of trichogynes growing from the cytoplasm out through the cell wall to the thallus surface. In another 24 h (day 2), the fertilized carpogonia had divided into carpospore packets. Spores were released at 1500 h the following day (day 3), their projections creating escape channels through the cell walls. [ABSTRACT FROM AUTHOR]