Oberwinkler, F. (1977) Das neue System der Basidiomyceten. In Beitra ¨ge zur Biologie der niederen Pflanzen (W. Frey, H. Hurka & F. Oberwinkler, eds): 59–104. Gustav Fischer Verlag, Stuttgart. Parmasto, E. (1995) Corticioid fungi: a cladistic study of a paraphy- letic group. Canadian Journal of Botany 73 (Suppl. 1): S843–S852. Michael Weiß Spezielle Botanik und Mykologie, Universita ¨ Tu ¨bingen, Auf der Morgenstelle 1, D-72076 Tu ¨bingen, Germany. E-mail : michael.weiss@umi-tuebingen.de DOI: 10.1017/S0953756204231173 NOMENCLATURAL CLARIFICATIONS AND NEW TAXA IN THE GLOMEROMYCOTA Pacispora (syn. Gerdemannia) We recently published the new generic name Gerdemannia, along with the family Gerdemanniaceae in the order Diversisporales, in Mycological Research (Walker et al. 2004). Some weeks after we submitted our paper, Oehl & Sieverding (2004) sent one estab- lishing the genus Pacispora to a different journal. Both publications describe the same clade of fungi and are based on the same type species Glomus scintillans S. L. Rose & Trappe 1980, but use different genus names. Hard copy of the Pacispora paper was effectively published in early June 2004, while that with Gerdemannia was not distributed until 23 June 2004. The genus name Pacispora consequently has priority and must be used under Art. 11.3 of the Code. The authors of Pacispora were informed of our intentions, but chose not to disclose theirs to us until after they had their paper in press, by which time it was too late for us to make any changes in the printed version of our paper. Gerdemannia is consequently a homotypic later synonym of Pacispora. Gerdemannia is therefore an illegitimate name which must be rejected (Art. 52.1). With respect to the species included in the genus, Oehl & Sieverding (2004) maintained Pacispora scintil- lans (the type species) and P. dominikii as separate species. However, the morphological and molecular data presented by Walker et al. (2004) show that the two names are synonyms, a conclusion which is shared by the original author of the name Glomus dominikii (Walker et al. 2004). Pacisporaceae fam. nov. and Gerdemanniaceae The family name Gerdemanniaceae, which we also introduced (Walker et al. 2004) remains validly pub- lished, but unfortunately is ruled as illegitimate because Gerdemannia is an illegitimate generic name (Art. 18.3). As Oehl & Sieverding (2004) did not introduce a new family name, it is necessary to do so here: Pacisporaceae C. Walker, Blaszk., Schuessler & Schwarzott, fam. nov. A familiis ceteris in Glomeromycota distincta combinatione sporae glomoideae, sporae tunicis internis flexibilibus, scu- tello germinationis, et sequentio DNA differenti. Sporocarpia ingnota. Mycorrhizas vesciculares-arbusculares formans. Typus : Pacispora Oehl & Sieverd. 2004. Diversispora gen. nov., Diversiporaceae fam. nov., and Diversisporales ord. nov. The ordinal and family designations Diversisporales and Diversisporaceae were used in Schu¨ ßler, Schwarzott & Walker (2001) but not validly published at that time pending a more detailed treatment of the group which will be submitted for publication shortly. However, in view of our experience with Gerdemannia, we take this opportunity to validly publish these names and the new generic name Diversispora here. The Diversisporales comprises the families Gigasporaceae, Acaulosporaceae, Diversisporaceae, and Pacisporaceae. Diversisporales C. Walker & Schuessler, ord. nov. A ordo ceteris in Glomeromycota distincta sequentio DNA differenti. Fungi hypogaei vel in parte epigaei ; formant endomycorrhizas arbusculares in radicibus cum plantis vivis. Vesiculae efformatae vel absentes. Cellulae auxiliares effor- matae vel absentes. Sporae glomoideae vel gigasporoideae vel acaulosporoideae. Typus : Diversisporaceae C. Walker & Schuessler 2004. Fungi hypogeous or partly epigeous, forming arbus- cular mycorrhizas, with or without vesicles, with or without hypogeous auxiliary cells. Forming either complex spores produced within a sporiferous saccule (acaulosporoid spores), complex spores developing from a bulbous base on the sporiferous hypha (giga- sporoid spores), or glomoid spores. Differing from other orders in the Glomeromycota by the possession of specific SSU rRNA gene sequence signatures, for example GGGTTTH and TYACCGGRAGGTRT corresponding to homologous positions 234 and 1495, respectively, of the S. cerevisiae SSU rRNA sequence J01353. Diversisporaceae C. Walker & Schuessler, fam. nov. A familiis ceteris in Diversisporales distincta combinatione sporae glomoideae, scutello germinationis absens, et sequen- tio DNA differenti. Typus : Diversispora C. Walker & A. Schuessler 2004. Differs from other families in the Diversisporales in the possession of glomoid spores, germination not accompanied by formation of a germination shield, and having specific SSU rRNA gene sequence signatures, for example GGCTCATTYGRRTYTS, ACYCA- TTRYCAGGCTTAAT, and TTGGCATTTAGYCA, Mycological Research News 981