As with many red algae, Fauchea laciniata has an isomorphic triphasic life cycle. It consists of two diploid and one haploid stage. The tetrasporophyte stage (2N) is elongate and irregular containing the tetrasporangia, located on the ventral side of the thallus only. Tetrasporangia asexually produce four 1N tetraspores which are cruciately divided (Vidargas, 2003). The tetraspore divides to form the 1N male and female gametophytes.
The male and female gametophytes are difficult to distinguish unless they are mature and reproductive. The antheridia of males creates a layer of gametes which are yellow in color and cause the male to be more pale and less iridescent than the female. Without this color difference males would be difficult to distinguish from females (Dawson, 1950). Female gametophytes have carpogonial branches containing eggs which become fertilized via spermatia to form reproductive structures called cystocarps. This is the third stage of the life cycle.
Cystocarps appear on both the faces and margins of the blades which is a distinguishing characteristic of F. laciniata from F. fryeana and F. galapagesis (Smith, 1969). A cystocarp is composed of the pericarp (1N) and the carposporophyte (2N). The carposporophyte is the home of the gonimnoblast and carposporangium, which produces carpospores. When carpospores are released they settle out of the water column and form the 2N tetrasporophyte to start the cycle over again.
There is some variation in this life cycle however. Male gametophytes appear to be absent in British Columbia populations, which suggests that in addition to sexual reproduction there is also some type of asexual reproduction taking place in the female gametophytes. The mechanism behind this could be apomeiotic cycling of the tetrasporophyte (Vijayaraghavan, 1997).
Dawson, E.Y.. “Notes on Pacific Coast Marine Algae.” American Journal of Botany 37.5 (1950): 339-341.
Smith, G.M. Marine Algae of the Monterey Peninsula California. 2nd ed. Stanford California: Stanford University Press, 1969.
Vidargas, N. Monterey Bay Aquarium Research Institute. 2003. 2 May 2008.
Vijayaraghavan, M.R. and B. Bhatia. Red Algae: Structure, Ultrastructure and
Reproduction. Darya Ganj, New Delhi: Aph Publishing Corporation, 1997.