Trebouxia gelatinosa
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| Trebouxia gelatinosa | |
|---|---|
Scientific classification  | |
| Kingdom: | Plantae |
| Division: | Chlorophyta |
| Class: | Trebouxiophyceae |
| Order: | Trebouxiales |
| Family: | Trebouxiaceae |
| Genus: | Trebouxia |
| Species: | T. gelatinosa |
| Binomial name | |
| Trebouxia gelatinosa Ahmadjian ex Archibald, 1975 | |
Trebouxia gelatinosa is a common symbiotic species of green alga in the family Trebouxiaceae. Formally described as new to science in 1975, it is usually found in association with different species of lichen-forming fungi.
The alga was originally isolated in 1960 by lichenologist Vernon Ahmadjian from the foliose lichen species now known as Flavoparmelia caperata. Patricia Archibald formally described the species in 1975.[1] The alga was later found to be a photobiont in Anzia, another genus of foliose lichens in the large family Parmeliaceae.[2]
Description
Trebouxia gelatinosa is characterised by its vegetative cells which are typically spherical, though occasionally they may be oviform (egg-shaped). During the log phase of growth, these cells measure between 5 and 16 micrometres (μm) in diameter and are encased in walls that are 1 μm or less in thickness. As the cells enter the stationary phase of their growth cycle, they do not increase significantly in size, but instead develop a gelatinous sheath around each individual cell, measuring 1.5 to 2 μm in thickness.[1]
The chloroplast within these cells is notable for containing a single, angular, and central pyrenoid, which appears to be encircled by a continuous sheath of starch, and each cell is uninucleate, meaning it contains a single nucleus.[1] The ultrastructure of the pyrenoids of most Trebouxia species has been catalogued and found to fall into eight different type based on the arrangements and forms of thylakoid lamellae within the pyrenoid matrix. The gelatinosa- type pyrenoids are traversed by thin parallel-arranged tubules. Knowing the pyrenoid structure sometimes enables the identification of some Trebouxia species in the lichen thallus without the need to culture the alga.[3]
Trebouxia gelatinosa reproduces through both zoospores and aplanospores. Zoospores are motile reproductive cells, measuring about 4 μm in width and 6 to 8 μm in length, with their nucleus located towards the rear or the middle of the cell. A stigma (a light-sensitive spot found in some algae) has not been observed in these cells.[1]