ABSTRACTUntil recently,Cribraria minutissimawas broadly described as having sporangia with or without a peridial cup (calyculus). The cupless form was recently given the nameCribraria confusa.Study of type specimens, specimens collected from different geographical areas, and scanning electron micrographs of sporangia support recognition of two distinct taxa.Cribraria minutissimais recognized by cupped sporangia, thickened, smooth upper rim of the cup sharply delimiting it from the peridial net, peridial net devoid of dictydine granules, reddish-orange spore mass, and spore ornamentation of obtuse spines. Surface ornamentation of the cup appears as rounded spherules (dictydine or plasmodic granules) shown with SEM, which often collapse, producing concavities.Cribraria confusadiffers fromC. minutissimain lack of peridial cup, bright yellow spore mass, smaller sporangia, and spores that bear sharply pointed spines and collapse along preformed lines. In some sporangia a basal disk may be present, or when absent, replaced by basal peridial strands. This disk could not be correlated with other characteristics.Cribraria confusais the smallest known taxon in the genusCribraria.