ORIGINAL ARTICLE Helicocentralis hyalina gen. et sp. nov., an aero-aquatic helicosporous fungus (Leotiomycetes, Ascomycota) in Thailand Veera Sri-indrasutdhi 1 & Clement K. M. Tsui 2 & Charuwan Chuaseeharonnachai 1 & Kaoru Yamaguchi 3 & Satinee Suetrong 1 & Izumi Okane 4 & Akira Nakagiri 5 & Nattawut Boonyuen 1 Received: 22 April 2015 /Revised: 9 August 2015 /Accepted: 17 August 2015 # German Mycological Society and Springer-Verlag Berlin Heidelberg 2015 Abstract During a survey of aero-aquatic fungi in Thailand, an undescribed helicosporous fungus was discovered. It is characterized by the presence of branched and septate hyphae with hyaline conidiophores that are micronematous or semi- macronematous, acrogenous and holoblastic. Conidia are hy- aline and centrifugally coiled (excentric), helicoid or circinate, coiled 2–3 times clockwise or counterclockwise. After com- parison of morphological and molecular characters with other aero-aquatic, helicosporous fungi, introduction of a new genus and species is proposed, Helicocentralis hyalina gen. et sp. nov. Phylogenetic analyses based on the combined sequence data from the small and large nuclear subunit ribosomal DNA (SSU and LSU), as well as internal transcribed spacer (ITS) rDNA sequence data, the fungus groups within the Leotiomycetes class with strong statistical support. The new genus is not related to other helicosporous hyphomycete genera ( Helicoma , Helicomyces , Helicoön , and Helicosporium), which belong in the Tubeufiaceae, Dothideomycetes. Within the Leotiomycetes, our new fungus is distantly related to Helicodendron paradoxum (the type species). The new fungus is also compared morphologically to six similar helicosporous genera from Dothideomycetes and Leotiomycetes. Keywords Aero-aquatic fungi . Freshwater . Dothideomycetes . Helicocentralis hyalina . Helicosporous hyphomycetes . Leotiomycetes . Molecular phylogeny . Wood . Thailand Introduction Aero-aquatic fungi are often found on submerged leaves and woody debris in freshwater habitats, i.e. slowly moving streams, wetlands, swamps and ponds. They are widely dis- tributed in both temperate and tropical locations (van Beverwijk 1951; Gönczöl and Révay 2003; Yamaguchi et al. 2012; Chuaseeharonnachai et al. 2013) and survive in low oxygen concentrations that might be adaptive to freshwater environments (Bärlocher et al. 1978; Fisher and Webster 1979, 1981; Abdullah and Webster 1980; Field and Webster 1983). Of these, the aero-aquatic helicosporous hyphomycetes are a large group, for example, the genera Helicomyces, Helicosporium, Helicoma, Helicodendron and Helicoön (Markovskaja 2012). Their common features are helicoid co- nidia, which have the axis curved through more than 180° (Tsui and Berbee 2006; Hawksworth et al. 1995; Zhao et al. 2007). During an ongoing ecological study of aero-aquatic fungi in north and northeast Thailand on their species abundance, diversity and frequency of occurrence (Chuaseeharonnachai Section Editor: Roland Kirschner * Veera Sri-indrasutdhi Veera@biotec.or.th 1 Fungal Biodiversity Laboratory, BIOTEC, National Science and Technology Development Agency (NSTDA), 113 Thailand Science Park, Thanon Phahonyothin, Tambon Khlong Nueng, Amphoe Khlong Luang, Pathum Thani 12120, Thailand 2 Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, BC V6T 1Z4, Canada 3 Biological Resource Center (NBRC), National Institute of Technology and Evaluation (NITE), 2-5-8 Kazusakamatari, Kisarazu, Chiba 292-0818, Japan 4 Faculty of Life and Environmental Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8572, Japan 5 Fungus/Mushroom Resource and Research Center, Faculty of Agriculture, Tottori University, 4-101 Koyama-Minami, Tottori, Tottori 680-8553, Japan Mycol Progress (2015) 14:81 DOI 10.1007/s11557-015-1103-6