Addition of ammonia or any nitrogenous materials to the soil that release ammonia causing alkaline condition during decomposition stimulates the fruiting of a particular chemoecological group of fungi, called ammonia fungi (Sagara 1975). The study of ammonia fungi by artificial application of urea in forest soil has been done in diverse geographical regions such as in Japan, Taiwan, New Zealand, Western Australia, and UK. Up to date about 70 species of ammonia fungi have been recorded in those regions. However, ammonia fungi in the boreal forest of American continent have not yet been investigated. Thus, we collected the soils of A0 and the upper layer of HA horizons in plant pots from aspen forest near Edmonton, Canada. Thereafter, we applied urea (granular fertilizer; 46% nitrogen, 10 mg/g dry soil) in plant pots and incubated at 25˚C under 12 hours dark and light regime. After 40 days of incubation, several basidiomata of Coprinopsis species appeared. Among them one specimen was identified as C. rugosobispora based on macro- and microscopic features. Morphologically this species was very similar to C. phlyctidospora which was characterized by warty, ovoid basidiospores, and diverticulate veil elements. C. phlyctidospora has 4-spored basidia while C. rugosobispora had only 2-spored. In the beginning, it was thought probably it was only a 2-spored form of C. phlyctidospora. The basidiospore of C. rugosobispora (9.8-11.7×8.3-9.6㎛) was distinctly larger than that of C. phlyctidospora (8.4-10.6×6.0-7.6 ㎛). It was therefore separated from the C. phlyctidospora. Furthermore in this study we investigated its phylogenetic relationship based on the nuclear rDNA sequence in ITS regions and mating reactions among its close allies and further confirmed it as a distinct species. This is the first record of C. rugosobispora from American continent since it has been collected only from Europe (Belgium and Netherlands). Although urea effectively stimulated its occurrence but it has not yet been reported any other urea application studies so far. This indicates it is a new record in ammonia fungi as well.