ABSTRACT: The new species Hypocenomyce oligospora and H. sierrae are described from North America; the former is widely distributed and also reported from Siberia, the latter is restricted to the mountains of southern California and Arizona. Both species are corticolous and lignicolous on conifers, often growing on charred substrates. They are closely related, differing mainly in the presence or absence of soredia. The species bridge the H. friesii- and H. scalaris-groups, and also show similarities with the H. xanthococca-group.

KEYWORDS: Lecanorales, taxonomy, North America, conifers, charred wood and bark.

NOMENCLATURAL NOVELTIES:
Hypocenomyce oligospora Timdal, p. 446
Hypocenomyce sierrae Timdal, p. 449