Hypocrella Sacc.; anamorph Aschersonia Montagne, nom. cons.
Stromata superficial, fleshy, usually brightly coloured, discoid or pulvinate (cushion-shaped). Ascomata globose to pyriform. Asci cylindrical, narrow, thin-walled, with a conspicuously thickened apex penetrated by a narrow canal; not blueing in iodine. Ascospores filiform, multiseptate, fragmenting into part-spores.
Conidiomata usually multilocular, the locules tubular, flask-shaped, ovoid or globose, without clearly-defined walls, releasing conidia though irregular splits. Conidiophores branched irregularly. Conidiogenous cells mostly arising as irregular lateral branches, ± cylindrical, producing conidia successively though, a single apical conidiogenous locus. Conidia usually ellipsoidal to fusiform, hyaline, aseptate.
Considering the interest in these fungi as agents of biological control, it is surprising that there has been no comprehensive monograph of Hypocrella and Aschersonia for seventy years (Fetch, 1921). Useful work on classification of the fungi has been contributed by Mains (1960). The book by Samson et al. (1988) is a useful modern source reference for this and other entomogenous fungi.
The best-known species is the common Aschersonia aleyrodis Webber, which is not known to have a teleomorph. It exerts a natural control over scale insects in the tropics, and is used as a biological control agent of the citrus whitefly Dialeurodes citri and the common greenhouse whitefly Trialeurodes vaporariorum. A. aleyrodis is described more fully by Brady (1984) and Sutton (1980).