BIOLOGY AND REPRODUCTIVE PROCESSES OF THE LARGER FORAMINIFERAN CYCLOCLYPEUS-CARPENTERI (PROTOZOA, NUMMULITIDAE)

Gamonts and agamonts of the extant nummulitid Cycloclypeus carpenteri were collected from a depth between 45 and 61 m, near Okinawa (Ryukyu Islands, Japan) and maintained in the laboratory in Kiel (Germany) unt il they reproduced. All of them grew in the laboratory, including dama ged specimens, which regenerated more or less regular tests. Like othe r nummulitids, they formed sheaths for attachment, complete in young a nd incomplete in adult specimens. Eighteen agamonts formed gamonts in the laboratory, the first reproducing after 5.5 months and the last af ter 9.2 months of maintenance. The process of multiple fission can be divided into 5 well defined periods. During the formation of the two-c hambered embryonic apparatuses, the symbiotic diatoms are apportioned to the daughter cells by a highly organized process that is identical in all nummulitids. The number of gamonts provided by 3 agamonts was 1 740, 1910 and 2540. The mean prolocular size in the two-chamber stage of the gamonts was 263 mu m (minimum 200 mu m, maximum 327 mu m). The mean size of 5 gamonts from the natural habitat was 8.1 mm on the day of reproduction. The mean size of 39 gamonts from laboratory culture w as 8.6 mm. Gamete formation began at an age of about 11 months and end ed at an age of about 13 months. Gamonts released their 2.5-3.0 mu m b iflagellated gametes over 0.7 to 15 hours mainly during the light peri od.