Species in genus
Byssoloma form
crustose, effuse (spreading) lichens that lack a (outer protective layer). Their , or
photosynthetic partner, is of the type, a form of
green algae. The
apothecia (fruiting bodies), are (directly attached to the thallus without a stalk) and approximately circular in shape. They lack a (a rim formed by the lichen thallus) and possess a , which is a layer of loosely arranged hyphae that can appear hairy or web-like (-) in some species. The
hymenium, the spore-bearing tissue, reacts with
iodine to turn blue (I+ blue). The , consisting of
paraphyses (filamentous support structures), is unbranched or slightly branched and not or only slightly thickened at the tips. The , a layer beneath the hymenium, is dark red-brown and may turn purple when treated with
potassium hydroxide (K) solution in European species. The
asci, which are the sac-like structures where spores develop, typically contain eight spores. They have thick walls and a blue-staining apical dome with a darker blue tubular ring structure and an
amyloid (starch-like) gelatinous coat. The are three-
septate (having three internal partitions), colourless, and found in European species. Asexual reproductive structures, the
pycnidia, are also sessile and roughly spherical, usually covered by a layer of loosely interwoven
hyphae. The
conidiophores (spore-producing cells) are unbranched, forming flask-shaped, (rod-like), or ellipsoidal
conidia (asexual spores) that are constricted in the middle. Chemically,
argopsin, a
secondary metabolite (
lichen product), is sometimes detected in one species, but otherwise,
Byssoloma lacks lichen products. ==Species==