Species of
Pilophorus have a two-part vegetative body (
thallus). The forms a thin crust that spreads across the
substrate and breaks into fine grains or small, tile-like patches (). From this crust arise the secondary structures—short, solid uprights commonly termed . Unlike those of
Cladonia, these stalks are not hollow. The outer "skin" () is poorly developed. The main
photosynthetic partner is a
green alga in the genus
Asterochloris, but small, internal wart-like bodies called
cephalodia also occur; these house cyanobacteria (
Nostoc or
Stigonema), allowing the lichen to
fix atmospheric nitrogen. The sexual fruiting bodies (
apothecia) sit at the tips of the pseudopodetia. They are almost spherical, lack a rim derived from the thallus (no ), and are characteristically black. Beneath the the supporting tissue () is dark brown. The internal tissue between the spore sacs (the ) consists of slender threads (
paraphyses) that are only sparingly branched and sometimes fuse, with tips that are barely swollen. The spore sacs (
asci) are club-shaped, contain eight spores, and are of the
Porpidia-type. The spores themselves are colourless, usually without internal
cross-walls (aseptate), and range from
ellipsoidal to spindle-shaped; they lack a distinct outer sheath ().
Asexual reproduction occurs in small, flask-like structures (
pycnidia) that are also formed at the tops of short pseudopodetia, often ringed by a collar of granules. These produce colourless, curved (sickle-shaped), non-septate
conidia from slender, cylindrical spore-forming cells. Chemically,
Pilophorus species contain the common
secondary metabolite (
lichen product)
atranorin, and may also contain
zeorin. They grow mainly on rock in
temperate, mountainous regions. The combination of black, globose apothecia on solid pseudopodetia helps separate
Pilophorus from similar genera:
Cladonia lacks black apothecia and usually has hollow stalks, while
Stereocaulon bears flat, red-brown apothecia and produces multi-celled spores (typically 2–14-celled). Within the Cladoniaceae, the way cephalodia are formed in
Pilophorus is distinctive to this genus. ==Species==