Erik Acharius treated the group as a
sectional concept within
Cenomyce (sect.
Pycnothelia) and centred it on the species long known as
Lichen papillaria. In his Latin he characterised the
taxon as a grey, granular, ramulose crust with discrete, erect, short, almost unbranched, hollow and somewhat swollen white ramuli bearing dark, globose tubercles (i.e. the little stalks are fistulose and end in round, dark apothecia). He also noted it is terrestrial and, because of the hollow, branched ramuli, allied to
Cladonia. Acharius listed contemporary
synonyms (e.g.
Cladonia papillaria Hoffm.) under the same concept. Dufour then lifted Acharius's sectional name to generic rank as
Pycnothelia (1821). Modern
multilocus work keeps
Pycnothelia as a good genus in Cladoniaceae, with three species currently accepted, and places it in a well-supported
clade with
Carassea and
Gymnoderma that is
sister to
Cladonia. For practical diagnosis at the generic level, authors emphasise the persistent primary thallus and the slender, hollow podetia that are or only branched near the tips, with a fully or partly surface. ==Description==