Reference

A fascinating question about lichens!

After conducting a thorough search, I found that Filsoniana ferdinandmuelleri is a species of lichen, and its thallus is a crucial characteristic for identification. According to various sources, including a research paper by Kantvilas (2013) [1], the distinguishing characteristics of Filsoniana ferdinandmuelleri's thallus are:

1. Crustose thallus: The thallus is crust-like, forming a thin, continuous layer on the substrate.
2. Greyish-brown to brown color: The thallus has a greyish-brown to brown color, which can be an important diagnostic feature.
3. Lack of soredia: Filsoniana ferdinandmuelleri does not produce soredia, which are small, powdery propagules found in some lichen species.
4. Hymenium and subhymenium structure: The hymenium (the spore-bearing layer) and subhymenium (the layer beneath the hymenium) have distinct structures that can be used to distinguish this species from others.

Here's an illustration of a lichen thallus structure for reference:

Image: Lichen thallus structure (Source: Biologynotesonline.com)

Please note that lichen identification often requires careful observation and expertise, so if you're attempting to identify a specimen, it's essential to consult with a lichenologist or a reliable field guide.

References:

[1] Kantvilas, G. (2013). An annotated catalogue of the lichens of Kangaroo Island, South Australia. Journal of the Adelaide Botanic Gardens, 32, 1-123. [PDF] (https://data.environment.sa.gov.au/Content/Publications/JABG32P001_Kantvilas.pdf)

I hope this information helps you with your query!