Submitted to: Mycological Progress
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/11/2004
Publication Date: 12/1/2004
Citation: Rossman, A.Y., Aime, M.C., Farr, D.F., Castlebury, L.A., Peterson, K., Leahy, R. 2004. The coelomycetous genera Chaetomella and Pilidium, a newly discovered lineage of inoperculate discomycetes. Mycological Progress. 3(4):275-290. Interpretive Summary: Species in the coelomycete genera Chaetomella and Pilidium are fungi that cause diseases of crop plants and trees. These fungi reproduce primarily without undergoing sex thus it is difficult to determine their relationship to other fungi. Accurate identification and knowledge of relationships among plant-associated fungi is essential for controlling the diseases they cause. In this paper morphological and molecular characteristics were used to determine that Chaetomella and Pilidium are closely related. In addition, it was discovered that these genera represent a previously unknown lineage that is allied with the inoperculate discomycetes. The type and commonly encountered species of Chaetomella and Pilidium are described and illustrated and a key for identification is presented. This research will be used by plant pathologists, extension agents and plant breeders to identify these fungi.
Technical Abstract: The coelomycetous genera Chaetomella and Pilidium were determined to be closely related to each other, yet are recognized as distinct genera based on both morphological observations and molecular sequence analyses. They are united by their black, thick-walled pycnidia opening by a raphae, and acropleurogenous conidiogenous cells. Pycnidia of Pilidium are smooth, while those of Chaetomella have setae of various types. A Hainesia synanamorph was observed in cultures of C. raphigera similar to H. lythri, the synanamorph of P. concavum. Chaetomella oblonga, type species of Chaetomella, C. raphigera, Pilidium acerinum, type species of Pilidium, and P. concavum were examined in detail with illustrations and descriptions provided for each species along with a key to the commonly encountered species. Analyses of the SSU and LSU of the nrDNA genes suggest that Chaetomella and Pilidium along with Sphaerographium tenuirostrum and an undescribed genus constitute a distinct lineage within the ascomycetes that is allied with the Leotiomycetes.