ORIGINAL ARTICLE Two new Ceratobasidium species causing white thread blight on tropical plants in Brazil Maruzanete P. de Melo 1 & Kedma S. Matos 2 & Silvino I. Moreira 3 & Fabiano F. Silva 3 & Grace H. Conceição 4 & Kátia L. Nechet 5 & Bernardo A. Halfeld-Vieira 5 & José E. A. Beserra Júnior 6 & José A. Ventura 7 & Hélcio Costa 7 & Edson L. Furtado 8 & Eduardo Alves 3 & Paulo C. Ceresini 4 Received: 7 March 2018 /Accepted: 26 June 2018 # Sociedade Brasileira de Fitopatologia 2018 Abstract White thread blight is one of the most common diseases affecting several tree species that grow in warm and humid regions. The typical symptoms of this disease include blighted leaves hanging by a white thread of fungal hyphae. Leaf samples exhibiting white thread blight symptoms were collected from neem (Azadirachta indica A. Juss) and Brazilian cherry pitanga (Eugenia uniflora L.) plants in Northeastern Brazil, and from Indian green-tea (Camellia sinensis (L.) O. Kuntze), coffee (Coffea arabica L.), and persimmon (Diospyros kaki L.) in agricultural areas neighboring the Atlantic forest in Southeastern Brazil. Fungal isolates were obtained indirectly from leaf fragments or directly by transferring mycelia and sclerotia to culture medium. Bright field and scanning electron microscopy images revealed the association of Rhizoctonia-like hyphae and basidiospores with the infected leaves. In pathogenicity tests, Rhizoctonia-like fungal isolates induced leaf necrosis on their hosts, and the pathogens were re- isolated from inoculated plants. Phylogenetic analyses based on sequences of the ITS rRNA region indicated the occurrence of Ceratobasidium lineages distinct from previously reported Ceratobasidium species. Our study leads to the description of two new species of Ceratobasidium: the fungal isolates from A. indica, C. sinensis, and E. uniflora were classified as Ceratobasidium niltonsouzanum sp. nov., and those obtained from C. arabica and D. kaki as Ceratobasidium chavesanum sp. nov. Keywords Binucleate Rhizoctonia . Phylogenetic analysis Introduction White thread blight was first described on coffee plants in Northern India. The fungal pathogen was initially described as Pellicularia koleroga Cooke (Cooke 1876). Typical signs of the disease include white mycelial cords visible on the infected branches and leaves. Diseased leaves dry up but re- main attached to the plant hanging by the fungal hyphae. Often, necrotic lesions are evident on the affected leaves. In severely colonized leaves, hymenia can be observed on the Section Editor: Simon Shamoun * Silvino I. Moreira silvinointra1@gmail.com 1 Universidade Federal do Oeste do Pará – UFOPA, Campus Juruti, Juruti, PA 68170-000, Brazil 2 Centro de Ciências Agrárias, Departamento de Fitotecnia, Universidade Federal de Roraima – UFRR, Boa Vista, RR 69310-000, Brazil 3 Departamento de Fitopatologia, Universidade Federal de Lavras – UFLA, Lavras, MG 37200-000, Brazil 4 Departamento de Fitossanidade, Engenharia Rural e Solos, Universidade Estadual Paulista “Julio Mesquita Filho”– UNESP, Ilha Solteira, SP 15385-000, Brazil 5 Empresa Brasileira de Pesquisa Agropecuária, Embrapa Meio Ambiente, Rodovia SP 340, Tanquinho Velho, Jaguariúna, SP 13820-000, Brazil 6 Centro de Ciências Agrárias, Departamento de Fitotecnia, Universidade Federal do Piauí – UFPI, Ininga, Teresina, PI 64049-550, Brazil 7 Instituto Capixaba de Pesquisa, Assistência Técnica e Extensão Rural – INCAPER, Vitória, ES 29052-010, Brazil 8 Departamento de Fitossanidade, Universidade Estadual Paulista “Julio Mesquita Filho”– UNESP, Botucatu, SP 18610-307, Brazil Tropical Plant Pathology https://doi.org/10.1007/s40858-018-0237-x