ISSN (print) 0093-4666 © 2010. Mycotaxon, Ltd. ISSN (online) 2154-8889 MYCOTAXON doi: 10.5248/113.377 Volume 113, pp. 377–384 July–September 2010 Chondrogaster pachysporus in a Eucalyptus plantation of southern Brazil Marcelo A. Sulzbacher 1 , Vagner G. Cortez 2 , Gilberto Coelho 3 , Rodrigo J. S. Jacques 1 & Zaida I. Antoniolli 1 marcelo_sulzbacher@yahoo.com.br & zantoniolli@gmail.com 1 Universidade Federal de Santa Maria, Departamento de Solos, CCR Campus Universitário, 971050-900, Santa Maria, RS, Brazil 2 Universidade Federal do Paraná R. Pioneiro 2153, 85950-000, Palotina, PR, Brazil 3 Universidade Federal de Santa Maria, Departamento de Fundamentos da Educação CE, Campus Universitário, 97105-900, Santa Maria, RS, Brazil Abstract — Chondrogaster pachysporus is reported for the first time in Brazil. It is similar to C. angustisporus, also known from southern Brazil, but differs in the size and ornamentation of the basidiospores and in the presence of monosporic basidia. Te hypogeous sequestrate specimens were collected in a Eucalyptus saligna plantation. Descriptions, photographs, and line drawings of the specimens are presented. Key words — ectomycorrhiza, false-truffle, Hysterangiales, Mesophelliaceae Introduction Chondrogaster Maire is a genus of sequestrate fungi characterized by enclosed hypogeous basidiomata that bear a loculate gleba composed of tramal plates where basidia and basidiospores are produced (Castellano et al. 1989). Te genus is closely related to Hysterangium Vittad., from which it was segregated and differs in the lack of a distinct columella and presence of a mycelial mass covering the whole basidioma (Giachini et al. 2000). Both currently known species are associated with Eucalyptus and possibly native to Australia but have spread to many areas where Eucalyptus plantations have been established for forestry purposes. Chondrogaster angustisporus Giachini et al., originally described from Australia, Uruguay, and southern Brazil (Giachini et al. 2000), is possibly the only South American record of the genus. Chondrogaster pachysporus, the type