AJELLOMYCES-CRESCENS SP-NOV, TAXONOMY OF EMMONSIA SPP, AND RELATEDNESS WITH BLASTOMYCES-DERMATITIDIS (TELEOMORPH AJELLOMYCES-DERMATITIDIS)

Adiaspiromycosis is known primarily as a pulmonary infection of small burrowing mammals and rarely of humans, in which the tissue spore form consists of a large, globose, thick-walled, non-proliferating structu re called an adiaspore. The causative agents have been placed in Emmon sia or Chrysosporium and treated as either two species or varieties. E mmonsia parva (= Chrysosporium parvum var. parvum) has been distinguis hed from E. crescens( = C. parvum var. crescens) by differences in max imum growth temperature, size of adiaspores, host range and geographic al distribution. Phenotypic similarities between Emmonsia spp. and Bla stomyces dermatitidis and chance observation of Ajellomyces-type ascom atal hyphae led to the hypothesis that the teleomorph of Emmonsia spp. could occur in Ajellomyces. Isolates preliminarily identified as E. p arva or E. crescens were examined by morphology and physiology and tes ted for compatibility in mating experiments, Ajellomyces crescens Sigl er sp. nov. is described for the teleomorph of Emmonsia crescens based on compatibility among 12 of 22 strains, stellate gymnothecial ascoma ta composed of obtuse diamond-shaped cells, helically coiled appendage s and small, globose, muriculate ascospores. The agents of adiaspiromy cosis are here treated as species with adiaspore size and morphology a nd temperature of induction as their major defining features. The spec ies differ also in cycloheximide tolerance and in their abilities to f orm a teleomorph. With evidence of a connection between Emmonsia cresc ens and a teleomorph in Ajellomyces, Emmonsia is favoured over Chrysos porium as the correct name for the agents of adiaspiromycosis. This fi nding also corroborates earlier suggestions of a close phylogenetic re lationship between Emmonsia spp. and the dimorphic pathogens Blastomyc es dermatitidis and Histoplasma capsulatum.