It has a widespread distribution, almost worldwide.[2] These smut fungi from Ustilaginomycotina contain about 540 described species. Species from the complex often possess characteristics that occur in more than one genus, creating uncertainty for species placement.[3]
Langdon & Fullerton (1977) established Macalpinomyces to accommodate M. eriachnes, which they considered as distinct from Sporisorium and Ustilago (other Smut (fungus) genera). As Macalpinomyces lacked columellae, produced sterile cells and the spores were uniformly ornamented and polyangular or sub-polyangular (Langdon & Fullerton 1977, Vánky 1996).[1] The original collection of M. eriachnes in Australia by the botanist Ferdinand von Mueller, was divided and sent to two mycologists, Mordecai Cooke in England and Felix von Thümen in Germany. They studied the specimens separately and then two new fungal taxa were described based on this single collection, Sorosporium eriachnes by Thümen in 1878 and Ustilago australis by Cooke in 1879.[1] Daniel McAlpine noted that the 2 types had large, smooth thick-walled cells.[5] Langdon & Fullerton (1977) agreed with McAlpine and later transferred this smut to a new genus, Macalpinomyces, nearly a century after the specimen was first described.[1]
Vánky in 1996, broadened the description of Macalpinomyces to include taxa that lacked a columella but possessed sterile cells, which are morphological features shared by both Sporisorium and Ustilago.[1]
Molecular phylogenetic analysis has shown that Macalpinomyces is polyphyletic. Species of Macalpinomyces have sterile cells, a peridium derived from host material and lack true spore balls (Vánky 2011b). Vánky (2011b) accepted 46 species of Macalpinomyces.[1]
The type species M. eriachnes was originally described from a specimen collected in northern Australia on the grass genus Eriachne in 1855. 10 new species were found in 2017, on the same grass in northern Australia.[6] Begerow et al. (2006), in their phylogenetic study of the Ustilaginomycotina, proposed that M. eriachnes might not belong to the Ustilaginaceae family as it did not occur in the clade containing Sporisorium, Ustilago and Moesziomyces.[1]