A new Gymnopus species with rhizomorphs and its record as nesting material by birds (Tyrannidae) in the subtropical cloud forest from eastern Mexico Author Cesar, Enrique Author Bandala, Victor M. Author Montoya, Leticia Author Ramos, Antero text MycoKeys 2018 42 21 34 http://dx.doi.org/10.3897/mycokeys.42.28894 journal article http://dx.doi.org/10.3897/mycokeys.42.28894 1314-4049--21 Gymnopus westii (Murrill) Cesar , Bandala & Montoya comb. nov. Basionym. Marasmius westii Murrill, Proc. Florida Acad. Sci. 7:110. 1945. Syn.: Marasmius brevipes Berk. & Ravenel, in Berkeley and Curtis, Ann. Mag. Nat. Hist., Ser. 2 12: 426. 1853. = Micromphale brevipes (Berk. & Ravenel) Singer, in Dennis, Kew Bull. 8: 42. 1953. Not Agaricus brevipes Bull., Herb. Fr. 11: tab. 521. 1791 ( Gymnopus , Gray, Nat. Arr. Brit. Pl. 1: 609.1821; Melanoleuca , Pat., Essai Tax. Hymenomyc .: 158, 1900.). Reports of marasmioid fungi as nesting material for Passeriformes have been referred in several works as filaments, rhizomorphs or horse-hair fungi and recorded from the Nearctic and the Neotropical regions ( Sick 1957 ; Mc Farland and Rimmer 1996; Aubrecht et al. 2013 ). These fungal materials have been identified as Marasmius androsaceus , M. brevipes , M. crinis-equi F. Muell. ex Kalchbr., M. nigrobrunneus (Pat.) Sacc. and M. sp. Fungal material from Marasmius sp. and Crinipellis sp. was recorded in Mexico as being associated with nests of birds in a tropical forest from Tabasco in the south of Mexico ( Gomez et al. 2014 ). In the present study, one of the sequences (MH560578), included in the obtained phylogeny (Fig. 1), belongs to a rhizomorph of Gymnopus nidus-avis re-collected in a nest of Myonectes oleaginous Lichtenstein. This Gymnopus species represents a new species in the list of marasmioid taxa found interacting with birds. All the basidiomes collected in the present study were found on fallen twigs in the low canopy level but it is possible that fructifications occur also on rhizomorphs at the top of the trees, where these latter are found and used by birds. Previous reports have suggested that bird efforts of picking this inconspicuous material is rewarded with the high tensile strength, reduced water uptake and antimicrobial properties of the rhizomorphs, which consequently protect the offspring ( Aubrecht et al. 2013 ; Freymann 2007 ). Preliminary results, based on various sequences obtained from rhizomorphs gathered in different nests of bird species found in the study site, suggest the presence of an important diversity of marasmioid rhizomorph-forming species in the cloud forest studied. It is interesting to note also that we could evidence the presence of nests of wasps of Polybia rejecta Fabricius, near one of Myonectes oleagineus built with rhizomorphs of Gymnopus . It coincides with the observations made by Joyce (1993) in Costa Rica regarding the presence of nests of that wasp species near Tolmomyas sulphurescens and Cacicus spp. nests. These latter authors concluded that such association could reduce predation, remarking the importance of the fungal rhizomorphs in this complex ecological interaction.