Phylogenetic and morphological studies in Xylodon (Hymenochaetales, Basidiomycota) with the addition of four new species Author Riebesehl, Janett Author Yurchenko, Eugene Author Nakasone, Karen K. Author Langer, Ewald text MycoKeys 2019 47 97 137 http://dx.doi.org/10.3897/mycokeys.47.31130 journal article http://dx.doi.org/10.3897/mycokeys.47.31130 1314-4049-47-97 Xylodon hyphodontinus (Hjortstam & Ryvarden) Riebesehl, Yurchenko & G.Gruhn comb. nov. Fig. 6 Odontiopsis hyphodontina Hjortstam & Ryvarden, Mycotaxon 12(1): 180 (1980) (Basionym). Typus of O. hyphodontina : TANZANIA, Morogoro Prov., Morogoro distr., Uluguri Mts., Morning Side Res. sta. ca. 5 km S of Morogoro, substrate unknown, leg. L. Ryvarden, 24-26 Feb 1973 (O L. Ryvarden 10949 - holotype). = Hydnum ambiguum Berk. & Broome, Journal of the Linnean Society, Botany 14(73): 60 (1873). Typus of H. ambiguum : SRI LANKA, Central Province, on dead wood (Berkeley No. 974 - holotype). = Odontiopsis ambigua (Berk. & Broome) Hjortstam, Mycotaxon 28(1): 35 (1987). = Pteridomyces sphaericosporus Boidin, Lanq. & Gilles, Mycotaxon 16(2): 490 (1983). Remarks. This new combination is based on the phylogenetic analyses of the ITS and 28S sequences as well as morphological study of specimens, including the holotype of O. hyphodontina . Originally, the collections from Martinique and French Guyana were identified as O. ambigua , but the molecular data clearly show that these collections are embedded in Xylodon (Figs 1, 2). Although H. ambiguum is the oldest name for this taxon, it cannot be transferred to Xylodon because the name is preoccupied by X. ambiguus (Peck) Kuntze (= Veluticeps ambigua (Peck) Hjortstam & Telleria). Odontiopsis ambigua , P. sphaericosporus and O. hyphodontina were recognised as conspecific by Hjortstam (1987 , 1991 ). Odontiopsis hyphodontina is the next oldest name and is chosen to represent this taxon. As O. hyphodontina is also the type of Odontiopsis Hjortstam & Ryvarden, Odontiopsis concomitantly becomes a synonym of Xylodon . The newly generated ITS and 28S sequences of X. hyphodontinus hold comparable positions in a clade that includes three distinct lineages in both phylogenetic trees (Figs 1, 2). Specimens KAS-GEL9222 from Kenya and LIP GG-GUY13-044 from French Guyana each represent distinct lineages from the third lineage of LIP GG-MAR15-127 and LIP GG-MAR12-238 from Martinique. As species in Hyphodontia s.l. can be readily distinguished with ITS or 28S sequences, these three lineages should result in the recognition of three different species. However, we were not able to identify any definite morphological differences amongst the lineages in comparison with the holotype material from Tanzania. Cultures are not available for these specimens, thus intercompatibility tests are not possible. As a result, we decided to treat all three lineages as X. hyphodontinus at this time.