What is the name of the asexual reproductive structure of a lichen that consists of a fungal hyphae wrapped around an algae?

The term that describes the asexual reproductive structure of a lichen, which consists of fungal hyphae wrapped around algae, is indeed soredia. Soredia are small clusters of algal cells surrounded by fungal hyphae that can disperse to form new lichen colonies. This reproductive strategy allows lichens to reproduce and spread effectively without the need for sexual reproduction. When soredia are released into the environment, they can settle on a suitable substrate, where they can grow into new lichen thalli through the partnership of the fungus and the algae, continuing the lichen's life cycle.

Thallus refers to the overall structure of the lichen itself, rather than a reproductive structure. Fragmentation is a process of asexual reproduction in some organisms but does not specifically describe the reproductive structure in lichens. Sessile refers to organisms that are fixed in one place and does not pertain to the reproductive structures. Thus, soredia is the most accurate term for the specific structure being asked about in the question.