Laboulbeniomycetes (Fungi, Ascomycota) of Denmark Author Santamaria, Sergi Unitat de Botànica, Departament de Biologia Animal, de Biologia Vegetal i d’Ecologia, Facultat de Biociències, Universitat Autònoma de Barcelona, 08193 Cerdanyola del Vallès (Barcelona), Spain. sergi.santamaria@uab.cat Author Pedersen, Jan Natural History Museum of Denmark (Zoological Museum), University of Copenhagen, Universitetsparken 15, 2100 København Ø, Denmark. japedersen@snm.ku.dk text European Journal of Taxonomy 2021 2021-11-26 781 1 425 http://dx.doi.org/10.5852/ejt.2021.781.1583 journal article 10.5852/ejt.2021.781.1583 2118-9773 5828924 Genus Corethromyces Thaxt. MB#1245 Proceedings of the American Academy of Arts and Sciences 27: 36 ( Thaxter 1892 ) . – Type species: C. cryptobii Thaxt. Eucorethromyces Thaxt., Proceedings of the American Academy of Arts and Sciences 35: 433 ( Thaxter 1900 ) [MB#1919] Brief description Monoecious. Receptacle three-celled. Primary appendage free, consisting of several superposed cells bearing lateral branches, some of them giving rise to intercalary but also terminal antheridia. Cells II and VI superposed, separated by a ± horizontal or oblique septum. Perithecium with four cells in each vertical row of outer wall cells. Remarks This is a large genus consisting of 92 species, of which 13 in Europe, three in Denmark . The most recently described species are C. gibbosus and C. marshallii (Rossi et al. 2020) . Hughes (2008) reported two undescribed species from Ptiliidae and Byrrhidae . Although Tavares (1985) redefined the too broad generic characteristics of the original description ( Thaxter 1892 ), it is still a genus with poorly defined limits. Corethromyces subsigmoideus Speg. ( Spegazzini 1917 ) is included here among the 92 species, although Tavares (1985) suggests that it could be a Cryptandromyces . Most species are associated with Col. Staphylinidae , but also with Carabidae , Leiodidae, Heteroptera Lygaeidae ( De Kesel & Haelewaters 2019 ) , and Diptera Sphaeroceridae (Rossi et al. 2020) . The number of perithecial wall cells may be questioned according to Weir & Hughes (2002) who mentioned five tiers instead of four at least in C. diochi Thaxt. ( Thaxter 1931 ) ; moreover, these authors suggested that the genus might be separated into two subgroups. Key to the Danish species (partially following Santamaria 2003 ) 1. Basal cell of the receptacle (I) blackish brown, extending laterally into a black outgrowth. On Rugilus (Col. Staphylinidae ).................................................................................................... C. stilici Thaxt. – Basal cell of the receptacle (I) not fully darkened, without a lateral expansion............................... 2 2. Basal cell of the appendage dark, supporting a few-celled axis bearing lateral slender phialides. Perithecial apex without a dark preapical spot. On Tachyporus Gravenhorst, 1802 (Col. Staphylinidae )..................................................................................... C. bialowiezensis T.Majewski – Basal cell of the appendage mostly entirely pale (rarely partially darkened), carrying several crowded sterile and fertile branches, the latter bearing intercalary phialides. Perithecium with a dark preapical spot. On Choleva (Col. Leiodidae ) .................................................... C. henrotii Balazuc ex Balazuc