The genus
Nevilleiella consists of
crustose lichens, which means they form a crust-like layer over their . These lichens are characterised by almost spherical, -like structures or by discrete, widely spread (small, cracked patches) that do not cover the entire surface. Their colour varies from brownish yellow to brownish orange, and they sometimes have a whitish, powdery coating (). The areoles themselves are quite diverse in shape, ranging from convex and warty to almost spherical, and they occasionally develop -like formations, which are small, split-off parts of the lichen. The , or the outer layer, has a tightly packed cellular structure (palisade ). The reproductive structures of
Nevilleiella, known as
apothecia, are typically of the form, meaning they have a clearly distinguishable margin and , but can sometimes become , where the margin is less distinct. The disc and its own margin are rusty brownish orange or brownish orange, blending in with the thallus. The , the outer layer of tissue surrounding the reproductive cells, also has a tightly packed cellular structure with a distinct matrix at the base. The , the layer beneath the reproductive cells, contains oil droplets. The are , meaning they have two cells divided by a nearly invisible
septum (internal partition), which is more visible when treated with a solution of
potassium hydroxide. The , a type of asexual spore, are narrowly rod-shaped, measuring 3–4
μm in length and 0.8–1 μm in width. Chemically,
Nevilleiella is defined by the presence of several
secondary metabolites (
lichen products). Parietin is the major chemical present, with
fallacinal as a somewhat major or minor component. It also contains
parietinic acid and
teloschistin, which are present in minor or trace amounts. The genus
Iqbalia, proposed in 2022 for the Pakistani species
Iqbalia kashmirensis, shares similarities with
Nevilleiella but can be distinguished by several key differences. Unlike
Nevilleiella,
Iqbalia features discrete, non-aggregated areoles and lacks schizidia-like formations. Its ascospores have a wide septum when observed in water. Additionally,
Iqbalia contains
variolaric acid and forms a distinct, strong
monophyletic branch within the subfamily Teloschistoideae. ==Habitat and distribution==