Micromelanconis kaihuiae gen. et sp. nov., a new diaporthalean fungus from Chinese chestnut branches in southern China Author Jiang, Ning https://orcid.org/0000-0002-9656-8500 The Key Laboratory for Silviculture and Conservation of the Ministry of Education, Beijing Forestry University, Beijing 100083, China Author Yang, Qin Forestry Biotechnology Hunan Key Laboratories, Central South University of Forestry and Technology, Changsha 410004, China Author Fan, Xin-Lei https://orcid.org/0000-0002-4946-4442 The Key Laboratory for Silviculture and Conservation of the Ministry of Education, Beijing Forestry University, Beijing 100083, China Author Tian, Cheng-Ming https://orcid.org/0000-0002-3352-7664 The Key Laboratory for Silviculture and Conservation of the Ministry of Education, Beijing Forestry University, Beijing 100083, China chengmt@bjfu.edu.cn text MycoKeys 2021 2021-04-16 79 1 16 http://dx.doi.org/10.3897/mycokeys.79.65221 journal article http://dx.doi.org/10.3897/mycokeys.79.65221 1314-4049-79-1 295791AF29C3591186E5AE19EF37C25B Micromelanconis C.M. Tian & N. Jiang gen. nov. Etymology. Name derived from micro- and the genus name Melanconis . Type species. Micromelanconis kaihuiae C.M. Tian & N. Jiang. Description. Sexual morph : not observed. Asexual morph : Conidiomata acervular, conspicuous, immersed in host bark to erumpent, covered by brown to blackish exuding conidial masses at maturity. Central column beneath the disc more or less conical. Conidiophores unbranched, aseptate, cylindrical, pale brown, smooth-walled. Conidiogenous cells annellidic, occasionally with distinct annellations and collarettes. Conidia hyaline when immature, becoming pale brown, ellipsoid, multiguttulate, aseptate, with hyaline sheath. Conidiomata formed on PDA after three weeks, randomly distributed, and black. Conidiophores unbranched, septate, cylindrical, pale brown, smooth-walled. Conidiogenous cells annellidic. Conidia pale brown, long dumbbell-shaped, narrow at the middle and wide at both ends, multiguttulate, aseptate, with hyaline sheath. Notes. Micromelanconis is the third genus after Neopseudomelanconis and Pseudomelanconis in the family Pseudomelanconidaceae (Fig. 1 ). Micromelanconis is united in this family based on the Melanconis -like conidiomata, and pale brown conidia with conspicuous hyaline sheath. Micromelanconis produces two types of conidia from natural branches and manual media respectively, which differs from Neopseudomelanconis and Pseudomelanconis ( Fan et al. 2018a ; Jiang et al. 2018a ). Additionally, Neopseudomelanconis is characterized by its septate conidia ( Jiang et al. 2018a ).