Species limits in the small genus Geopyxis

 are debatable because of problems with interpreting

the few phenotypic features and poor documentation

of types. To clarify species boundaries and diversity,

we studied the morphology of 74 specimens of Geopyxis

 from the Northern Hemisphere, including five types,

and sequenced four loci for 57 representatives: the

nuc rDNA ITS1-5.8S-ITS2 (ITS), D1-D2 domains of

nuc 28S rDNA (28S), translation elongation factor

(tef1 ), and (or) part of the second largest subunit of

the RNA polymerase II (rpb 2) (5– 7 region). Eight species

are delimited. Six species are shown to be highly

supported as reciprocally monophyletic: G. aleurioides

 sp. nov., G. alpina  s. l., G. carbonaria , G. delectans , G.

korfii , and G. majalis . In addition, coalescent-based

Bayesian species delimitation shows G. alpina  s. l. constitutes

three cryptic species: G. alpina  s. str., G. deceptiva

 sp. nov., and G. rehmii . ITS-28S sequences of type

material show that G. vulcanalis  and G. foetida  are synonyms

of G. carbonaria . A lectotype is designated for

Humaria delectans  and the name is combined in Geopyxis .

Morphological characters that can be used to distinguish

Geopyxis  species are presence/absence of a

long stipe, spore size and shape, and pigmented resinous

exudates in medullary and ectal excipulum. Geopyxis

carbonaria  and G. delectans  produce apothecia

almost exclusively on burned ground. Bayesian analyses

detected highly supported conflicts among different

loci regarding generic delimitation and species

relationships. Two hypogeous genera, Stephensia  and

Hydnocystis , are confirmed to nest within Geopyxis . The

relationships between species of Geopyxis  and Tarzetta ,

Stephensia shanorii  and Paurocotylis pila , are unresolved.

Six out of eight species of Geopyxis  recognized in this

study have intercontinental disjunct distributions.