Pseudophaeocytostroma bambusicola gen. et sp. nov. (Diaporthaceae) from bamboo in Yunnan, P. R. China Author Monkai, Jutamart 0000-0001-6043-0625 Research Center of Microbial Diversity and Sustainable Utilization, Faculty of Science, Chiang Mai University, Chiang Mai 50200, Thailand & Department of Biology, Faculty of Science, Chiang Mai University, Chiang Mai 50200, Thailand & mjutamart @ gmail. com; https: // orcid. org / 0000 - 0001 - 6043 - 0625 mjutamart@gmail.com Author Phookamsak, Rungtiwa 0000-0002-6321-8416 Research Center of Microbial Diversity and Sustainable Utilization, Faculty of Science, Chiang Mai University, Chiang Mai 50200, Thailand & Honghe Center for Mountain Futures, Kunming Institute of Botany, Chinese Academy of Sciences, Honghe 654400, P. R. China & jomjam. rp 2 @ gmail. com; https: // orcid. org / 0000 - 0002 - 6321 - 8416 jomjam.rp2@gmail.com Author Xu, Sheng 0000-0002-8911-3751 Research Center of Microbial Diversity and Sustainable Utilization, Faculty of Science, Chiang Mai University, Chiang Mai 50200, Thailand & Department of Biology, Faculty of Science, Chiang Mai University, Chiang Mai 50200, Thailand & Honghe Center for Mountain Futures, Kunming Institute of Botany, Chinese Academy of Sciences, Honghe 654400, P. R. China & hambugerking 123 @ gmail. com; https: // orcid. org / 0000 - 0002 - 8911 - 3751 hambugerking123@gmail.com Author Xu, Jianchu 0000-0002-2485-2254 Honghe Center for Mountain Futures, Kunming Institute of Botany, Chinese Academy of Sciences, Honghe 654400, P. R. China & Centre for Mountain Futures (CMF), Kunming Institute of Botany, Kunming 650201, P. R. China & CIFOR-ICRAF China Program, World Agroforestry (ICRAF), Kunming 650201, P. R. China & jxu @ mail. kib. ac. cn; https: // orcid. org / 0000 - 0002 - 2485 - 2254 jxu@mail.kib.ac.cn Author Mortimer, Peter E. 0000-0002-8507-7407 Centre for Mountain Futures (CMF), Kunming Institute of Botany, Kunming 650201, P. R. China & peter @ mail. kib. ac. cn; https: // orcid. org / 0000 - 0002 - 8507 - 7407 peter@mail.kib.ac.cn Author Karunarathna, Samantha C. 0000-0001-7080-0781 Center for Yunnan Plateau Biological Resources Protection and Utilization, College of Biological Resource and Food Engineering, Qujing Normal University, Qujing 655011, P. R. China & samantha @ mail. kib. ac. cn; https: // orcid. org / 0000 - 0001 - 7080 - 0781 samantha@mail.kib.ac.cn Author Suwannarach, Nakarin 0000-0002-2653-1913 Research Center of Microbial Diversity and Sustainable Utilization, Faculty of Science, Chiang Mai University, Chiang Mai 50200, Thailand & Department of Biology, Faculty of Science, Chiang Mai University, Chiang Mai 50200, Thailand & suwan _ 461 @ hotmail. com; https: // orcid. org / 0000 - 0002 - 2653 - 1913 suwan_461@hotmail.com Author Lumyong, Saisamorn 0000-0002-6485-414X Research Center of Microbial Diversity and Sustainable Utilization, Faculty of Science, Chiang Mai University, Chiang Mai 50200, Thailand & Department of Biology, Faculty of Science, Chiang Mai University, Chiang Mai 50200, Thailand & Academy of Science, The Royal Society of Thailand, Bangkok 10300, Thailand & scboi 009 @ gmail. com; https: // orcid. org / 0000 - 0002 - 6485 - 414 X scboi009@gmail.com text Phytotaxa 2022 2022-11-01 571 1 39 51 journal article 177065 10.11646/phytotaxa.571.1.3 5b9115aa-3e83-4df8-a6fb-05970057f400 1179-3163 7270446 Pseudophaeocytostroma Monkai & Phookamsak , gen. nov. Index Fungorum number : IF559820; Facesoffungi number : FoF 12716 Etymology : “ Pseudophaeocytostroma ” refers to the morphological similarity to the genus Phaeocytostroma . Saprobic on dead bamboo culms. Sexual morph : Undetermined. Asexual morph : Coelomycetous. Conidiomata pycnidial, immersed in the clypeus, becoming raised, erumpent, penetrating on host surface, with small black dots of conidial masses, hemispherical to subconical or lenticularis, uni- to bi-loculate, with an ostiole at the center, occasionally produced 2 ostioles in a locule, glabrous. Ostioles minutely papillate, immersed in host epidermis, circular. Conidiomatal wall consist of several layers of pseudoparenchymatous cells, arranged in a textura angularis , with dark brown outer layers and hyaline to pale brown towards the inner layers. Paraphyses intermingled between conidiophores, broadly filiform, septate, hyaline, unbranched, obtuse at the apex, with small granules. Conidiophores tightly aggregated, subcylindrical to ampulliform, or irregular in shape, septate, hyaline to pale brown, branched only at the base. Conidiogenous cells enteroblastic, phialidic, determinate, integrated, subcylindrical, tapering towards the apex, hyaline, smooth-walled. Conidia oblong to ellipsoid, obtuse at both ends, aseptate, brown, thick and smoothwalled, guttules. Type species:— Pseudophaeocytostroma bambusicola Monkai & Phookamsak Notes:— Pseudophaeocytostroma resembles the generic description of Phaeocytostroma including immersed, uni- to multilocular conidiomata, filiform paraphyses and aseptate conidia ( Sutton 1980 ). However, their conidial shapes are different as Pseudophaeocytostroma has oblong to ellipsoid conidia, while Phaeocytostroma has ellipsoid to fusiform or pyriform conidia ( Sutton 1980 ). Pustulomyces also has aseptate conidia, but can be distinguished from Pseudophaeocytostroma by pustule-like conidiomata and fusiform or sigmoid conidia ( Dai et al. 2014 ). Pseudophaeocytostroma is different from Massariothea which produces distoseptate conidia, but they are similar in having uni- to multilocular conidiomata, ostiolate and filiform paraphyses ( Thambugala & Hyde 2018 ). Stenocarpella differs from Pseudophaeocytostroma in having unilocular, elongated conidiomata, lacking paraphyses and 0–3 septate conidia ( Sutton 1980 , Lamprecht et al. 2011 ). Phylogenetic analyses results showed that Pseudophaeocytostroma clustered with Pustulomyces with 50% ML support and both genera formed a well-resolved clade basal to Phaeocytostroma sensu stricto , Massariothea and Stenocarpella with 78% ML and 76% MP support ( FIGURE 1 ). The weak support in Pustulomyces is probably caused by the single strain. Pustulomyces also formed a separate branch basal to Pseudophaeocytostroma with no support in BI analysis, thus more sequence data from fresh collections are essential to resolve its phylogenetic placement. Therefore, we introduce Pseudophaeocytostroma as a new genus in Diaporthaceae based on a strong support in phylogenetic incongruence to other related genera (viz. Phaeocytostroma , Pustulomyces , Massariothea and Stenocarpella ), although the morphological characteristics of Pseudophaeocytostroma and Phaeocytostroma are not significantly different.