The most common photobiont from green algae in lichen thallus is

Options

A. Trebouxia
B. Tetraspora
C. Chlamydomonas
D. Ulothrix.

Answer

To solve the question regarding the most common photobiont from green algae in lichen thallus, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Components of Lichens**:
- Lichens are composite organisms made up of two main components: a fungal partner (mycobiont) and a photosynthetic partner (photobiont), which is usually an alga.

2. **Identify the Types of Algae**:
- The photobiont can be either green algae (Chlorophyta) or blue-green algae (Cyanobacteria). In this question, we are specifically looking for green algae.

3. **Analyze the Options Provided**:
- The options given are:
- A) Triboxia
- B) Tetraspora
- C) Chlamydomonas
- D) Eulothrix

4. **Evaluate Each Option**:
- **Triboxia**: This is a unicellular green alga that is known to form associations with fungi to create lichens.
- **Tetraspora**: This is also a unicellular green alga but is not commonly associated with lichens.
- **Chlamydomonas**: Another unicellular green alga, but it does not typically form lichens.
- **Eulothrix**: This is a non-branching, non-filamentous green alga that does not form a part of lichens.

5. **Determine the Most Common Photobiont**:
- Among the options, **Triboxia** is recognized as the most common photobiont from green algae in lichen thallus. It is specifically noted for its role in forming lichens with fungi.

6. **Final Answer**:
- The most common photobiont from green algae in lichen thallus is **Triboxia**.