Nova Hedwigia 80 3—4 413—417 Stuttgart, May 2005 Chaetomium acropullum sp. nov. (Chaetomiaceae, Ascomycota), a new psychrotolerant mesophilic species from China by Xue-wei Wang1 and Ru-yong Zheng2* Key Laboratory of Systematic Mycology and Lichenology, Institute of Microbiology Chinese Academy of Sciences, Beijing 100080, China 1e-mail: [email protected] 2Corresponding author, e-mail: [email protected] With 4 figures and 1 table Wang, X.-w. & R.-y. Zheng (2005): Chaetomium acropullum sp. nov. (Chaetomiaceae, Ascomycota), a new psychrotolerant mesophilic species from China. - Nova Hedwigia 80: 413-417. Abstract: Chaetomium acropullum sp. nov., isolated from soil in China, is described and illustrated. The new species shows a striking contrast between the dark apical area and the paler lower part of the ascoma. The mycelial growth rates in relation to temperatures from 5-40°C were determined. Key words: Chaetomium acropullum sp. nov., taxonomy, growth-temperature relationships. Introduction Chaetomium Kunze is the largest genus of the Chaetomiaceae G. Winter. In a revision by von Arx et al. (1986), 91 out of 319 published species were accepted. But many of the postulated synonymies require a critical reassessment. Over 20 more names have subsequently been published. While collecting and examining Chaetomium species in China, an isolate was found to be distinct from all previously described species in a combination of morphological characters. This fungus is somewhat similar to Chaetomium thermophilum La Touche in the shapes of asci and ascospores, but it is mesophilic. Hence it is described as a new species. Materials and methods ORIGIN OF THE ISOLATE: Strain 9538-17 was isolated from garden soil in Shennongjia, a mountainous region of Hubei province. About 1 g air-dry soil was mixed with 10 ml sterile water in a test tube and shaken for 5 min. After a few seconds of sedimentation, a small amount of the suspension free of DOI: 10.1127/0029-5035/2005/0080-0413 0029-5035/05/0080-0413 $ 1.25 © 2005 J. Cramer in der Gebrüder Borntraeger Verlagsbuchhandlung, D-14129 Berlin · D-70176 Stuttgart 413.