Fauchea: epiphytes on Fauchea laciniata
Several species of algae grow on Fauchea epiphytically. Some, like Antithamnion defectum, grow on the stipe, what we might call the "trunk." Others, like this purple coralline, seen in the upper part of this picture (right on the tip of my middle finger), will grow on and even through the blades (well, more like the blades grew around the coralline).
Antithamnion defectum was found on several of my F. laciniata samples, growing in mats on the stipes of the algae. A. defectum is a filamentous alga in the Phylum Rhodophyta, Class Floridophyceae, Order Ceramiales, Family Ceramiaceae. It is a purely epiphytic plant found in the inter- and subtidal to 10 m.
The main branches, of which this is merely the top half, are between 2 and 4 cm tall, and grow in groupings, or mats, of branches. Coming off the main branch are first branchlets that are soon replaced with branches. Off of these branches come new branchlets, but these lack opposite branchlets and only grow upward. A few ovoid tetrasporangial cells can be seen in this image, left of center. This image is less than 0.25 cm wide.
These gland cells are the tetrasporangial clusters (<80 microns each), containing the third life phase of Antithamion. They are, however, empty of their tetraspores as this sample appeared to have released them soon after collection. This alga goes through the same tri-partite life cycle as all the reds but cystocarps were not found, nor were obvious gametophyte reproductive structures. See any of the texts mentioned in acknowledgements for depictions.
The more notorious epiphyte on Fauchea is that of the genus Faucheocolax. To read about how this species may have evolved from Fauchea fryeana .and involved itself in the evolution of F. laciniata see the evolution page.
Faucheocolax looks simply like a miniature of Fauchea with a few differences. Its thalli are minute, around 2mm in diameter, while the color is more pinkish than the deep reds we see in Fauchea. What's more, Faucheocolax lacks our favorite trait, the blue iridescence.
Fertile branches are mostly forked instead of flabellate. The cystocarps, rather than being spread across the thallus, exist only at the margins, like many of the other Fauchea species. But the vegetative structure, cystocarps, and cruciate tetrasporangia are essentially the same as Fauchea.
Unfortunately, as Faucheocolax flourishes a bit later than Fauchea, it was not found on any samples. Presumably it will be more abundant in spring. Thus, no images are available. Please see Abbot and Hollenberg's, or Smith's book for descriptions and drawings.