Acaromyces ingoldii culture on PDA. Bar = 2.5 mm. Photo: Teeratas Kijpornyongpan.

Acaromyces ingoldii Boekhout, Scorzetti, Gerson & Sztejnb. was first isolated and described from a citrus rust mite in Israel (Boekhout et al., 2003).  Biocontrol experiments showed a high mortality rate of several mite species after A. ingoldii inoculation (Boekhout et al., 2003).  Later studies showed that toxic chemicals secreted by the fungus were responsible for mite mortality (Paz et al., 2007; Gerson et al., 2008). As there is no report of Acaromyces species causing damage to plants, they may serve as promising biological agents for integrated pest management.  
The strain of A. ingoldii used for genome sequencing was isolated from a leaf phylloplane in Scotland. The fungus forms discrete white, velvety to pruinose colonies on potato dextrose agar (PDA). Microscopically, it is composed of hyaline septate hyphae with blastoconidia formed in acropetal chains. Acaromyces is a monotypic yeast-like genus that is morphologically similar to the anamorphic “smut” (subphylum Ustilaginomycotina) fungus genus Pseudozyma, and in its mite-associated habit with another anamorphic smut genus, Meira. However, while phylogenetic analyses of several nuclear rDNA loci support the placement of Acaromyces within the Exobasidiales (Exobasidiomycetes, Ustilaginomycotina), it is not a close relative of either Pseudozyma or Meira species, but rather belongs to Cryptobasidiaceae (Boekhout et al., 2003, Rush and Aime, 2013). Whether A. ingoldii possess a sexual state remains unknown (Boekhout et al. 2003).
The genome sequence of A. ingoldii will provide the first whole genome reference sequence for a member of Cryptobasidiaceae. Researchers will use these data in phylogenetic and phylogenomic reconstructions and in comparative genomics studies that seek to elucidate the molecular bases governing production of sexual and anamorphic states, invertebrate toxins, and the evolution of phytopathogenicity in Ustilaginomycotina.

References:
Boekhout T, Theelen B, Houbraken J, Robert V, Scorozetti G, Gafni A, Gerson U, Sztejnberg A. 2003. Novel anamorphic mite-associated fungi belonging to the Ustilaginomycetes: Meira geulakonigii gen. nov., sp. nov., Meira argovae sp. nov. and Acaromyces ingoldii gen. nov., sp. nov. International Journal of Systematic and Evolutionary Microbiology 53:1655–166.
Gerson U, Gafni A, Paz Z, Sztejnberg A. 2008. A tale of three acaropathogenic fungi in Israel: Hirsutella, Meira and Acaromyces. Experimental and Applied Acarology 46:183–194.
Paz Z, Gerson U, Sztejnberg A. 2007. Assaying three new fungi against citrus mites in the laboratory, and a field trial. Biocontrol 52:855–862.
Rush TA, Aime MC. 2013. The genus Meira—phylogenetic placement and description of a new species. Antonie van Leeuwenhoek 103:1097-1106.