Macrophomina Petr., Annls mycol. 21(3/4): 314 (1923).
Mycelium superficial or immersed, brown to hyaline, branched, septate, often dendroid in culture. Sexual morph: Unknown. Asexual morph: Conidiomata pycnidial, stromatic, separate, globose, dark brown, immersed, unilocular, thick-walled, wall consisting of an outer layer of dark brown thick-walled textura angularis, becoming hyaline towards the inside. Ostiole central, circular, papillate. Conidiophores absent. Conidiogenous cells enteroblastic, phialidic, determinate, discrete, lageniform to doliiform, hyaline, smooth, with wide aperture and minute collarette, formed from the inner cells of the pycnidial wall. Conidia hyaline, aseptate, obtuse at each end, straight, cylindrical to fusiform, thin-walled, smooth, guttulate. Sclerotia black, smooth, hard, formed of dark brown, thick-walled cells (adapted from Phillips et al. 2013).
Type species: Macrophomina philippinensis Petr.
Notes: Macrophomina is characterised by pycnidial, stromatic, separate, globose, dark brown conidiomata, enteroblastic, phialidic, determinate conidiogenous cells, and hyaline, aseptate, cylindrical to fusiform, thin-walled, smooth conidia. Arx (1981) synonymized Macrophomina with Tiarosporella and provided the combination Tiarosporella phaseolina based on the presence of apical mucoid appendages in the conidia. This treatment was not followed by subsequent authors except Arx (1987). Macrophomina resembles Tiarosporella in having apical mucoid appendages but has percurrently proliferating conidiogenous cells, and dark-brown microsclerotia which are lacking in Tiarosporella. Holliday and Punithalingam (1988) described the conidiophores of Macrophomina as hyaline, phialidic, short obpyriform to cylindrical. Macrophomina phaseolina is also the coelomycete synasexual morph of Rhizoctonia bataticola (Phillips et al. 2013). There has been considerable debate regarding the synasexual morph, and its taxonomic placement. Crous et al. (2006) induced several strains of M. phaseolina to sporulate on sterile pine needles, reported apical mucoid appendages in the conidia and provided an emended description of the genus. Crous et al. (2006) accepted Macrophomina in Botryosphaeriaceae. Macrophomina is morphologically and phylogenetically a distinct genus in Botryosphaeriaceae. Molecular markers are available for Macrophomina species namely M. euphorbiicola (ITS, BTUB, Actin, Calmodulin, TEF-1), M. phaseolina (ITS, SSU, LSU, BTUB and TEF-1, mtSSU), M. pseudophaseolina (ITS, Actin, BTUB, Calmodulin, TEF-1) and M. vaccinia (ITS, Actin, BTUB, TEF-1).