Life history and reproduction of cordylecladia erecta (Rhodymeniaceae, rhodophyta)

Spermatangial, carposporangial and tetrasporangial plants of Cordylecladia erecta are found sporadically from September to April inclusive. Cultured tetraspores from plants collected on the west coast of Ireland formed dioecious gametangial plants at 15°C, under short day conditions and under an interrupted dark period, while control plants under long day conditions, remained sterile. Carpospores from the carposporophytes of fertilized female plants in culture formed tetrasporangial plants under short day conditions at 15°C and 10°C, as well as under an interrupted dark period iat 15°C. Control plants under long day conditions at 15°C, and with interrupted dark period at 10°C remained sterile. C. erecta thus has a Polysiphonia-type life history, with reproduction under photoperiodic control. Procarps are described for the first time from cultured female plants. They are formed in small depressions surrounded by sterile hairs. The carpogonial branch is four-celled, and the carpogonium forms a strongly emergent trichogyne that protrudes amongst the sterile hairs. Carpogonial branches are formed on a supporting cell that also bears a two-celled auxiliary cell branch, which is formed before fertilization. Development of the carposporophyte takes place outwards from a fusion cell. Tetrasporangia are formed in an intercalary position on modified cortical filaments. These reproductive details confirm the current placement of the genus Cordylecladia in the family Rhodymeniaceae (Rhodymeniales), close to Rhodymenia.