Hysterium pulicare. Photo courtesy of Dr. E. Boehm

Hysterium pulicare. Photo courtesy of Dr. E. Boehm

Hysterium pulicare (Lightf.: Fr.) Pers. is a poorly known saprobic species. It occurs on living tree bark or dead wood of numerous species of angiosperms and gymnosperms. It produces unique ascocarps (sexual structures), called hysterothecia, which are darkly pigmented and carbonaceous. The hysterothecium is a variable boat-like structure with a pronounced lengthwise slit to release the dark, three-septate sexual spores. Due to its seemingly transitional nature, neither fully open nor closed these fungi has been interpreted as related to very different groups throughout history. Recent phylogenetic analyses have demonstrated, however, that the hysterothecium has been derived multiple times. These studies also showed considerable unexpected genetic diversity in hysteraceous fungi. Hysterium is now classified in the family Hysteriaceae of the order Hysteriales and class Dothideomycetes (Boehm et al. 2009).

Dothideomycetes is the largest class of ascomycete fungi and contain species with diverse ecologies and nutritional modes, including plant pathogens, insect pathogens, lichens, marine fungi and saprobes. Two large orders contain the majority of economically important plant pathogens and Hysteriales is the sister order to one of them, the Pleosporales. Current phylogenetic hypotheses support a saprobic nutritional mode as ancestral in the class with multiple derivations of pathogens, autotrophic symbioses and unique life styles (Schoch et al. 2009). The genome of H. pulicare, along with those from other saprobic taxa, will allow a greater understanding of the metabolic diversity of Dothideomycetes and the genomic diversifications associated with shifts between major ecologies and nutritional modes.

• Boehm, E.W.A., Mugambi, G.K., Miller, A.N., Huhndorf, S.M., Marincowitz, S., Spatafora, J.W. and C.L. Schoch.  2009. A molecular phylogenetic reappraisal of the Hysteriaceae, Mytilinidiaceae and Gloniaceae (Pleosporomycetidae, Dothideomycetes) with keys to world species. Studies in Mycology 64: 49-84.
• Schoch, C.L., Crous, P.W., Groenewald, J.Z., Boehm, E.W.A., Burgess, T.I., De Gruyter, J., De Hoog, G.S., Dixon, L.J., Grube, M., Gueidan, C., Harada, Y., Hatakeyama, S., Hirayama, K., Hosoya, T., Huhndorf, S.M., Hyde, K.D., Jones, E.B.G., Kohlmeyer, E.B.G., Kruys, Å., Lücking, R., Lumbsch, H.T., Marvanová, L., Mbatchou, J.S., McVay, A.H., Miller, A.N., Mugambi, G.K., Muggia, L., Nelsen, M.P., Nelson, P., Owensby, C A., Phillips, A.J.L., Phongpaichit, S., Pointing, S.B., Pujade-Renaud, V., Raja, H.A., Rivas Plata, E., Robbertse, B., Ruibal, C., Sakayaroj, J., Sano, T., Selbmann, L., Shearer, C.A., Shirouzu, T., Slippers, B., Suetrong, S., Tanaka, K., Volkmann-Kohlmeyer, B., Wingfield, M.J., Wood, A.R., Woudenberg, J.H.C., Yonezawa, H., Zhang, Y. and J.W. Spatafora. 2009. A class-wide phylogenetic assessment of Dothideomycetes.  Studies in Mycology  64: 1-15.