Belg. Journ. Bot. 134 (2) : 127-130 (2001) CLADONIICOLA STAUROSPORA GEN. ET SP. NOV. , A NEW LICHENICOLOUS COELOMYCETE FROM WESTERN EUROPE Paul DIEDERICH Musee national d'histoire naturelle, 25 rue Munster, L-2160 Luxembourg, Luxembourg (paul.diederich@ci.educ.lu) Pieter VAN DEN BOOM Arafura 16, NL-5691 JA Son, The Netherlands (pvdboom@zonnet.nl) Andre APTROOT Centraalbureau voor Schimmelcultures, P. O. Box 85167, NL-3508 AD Utrecht, The Netherlands (aptroot@cbs.knaw.nl) ABSTRACT. - A new lichenicolous coelomycete is described as Cladoniicola staurospora gen. et sp. nov. It has immersed pycnidia in which hyaline, branched, transversally septate conidia are produced holoblastically from ampulliform conidiogenous cells. The new fungus is confined to squamules of the primary thallus of terricolous Cladonia species, which become decolourized. It is currently known from the Netherlands and northern France. KEy WORDS. - Lichenicolous fungi, coelomycetes, Cladoniicola, Cladonia. INTRODUCTION For several years we repeatedly collected specimens of an unknown lichenicolous coelomy- cete, developing on squamules of the primary thallus of Cladonia, in the Netherlands and in northern France. Although the branched, hyaline conidia of this fungus superficially recall species of the fungicolous (inc!. lichenicolous) coelomy- cete genus Cornutispora, the conidiogenesis and the conidia are nevertheless very distinct. As no similar genus could be found in either NAG RAJ (1993) or SUTION (1980), the description of a new genus seems to be appropriate. MATERIAL AND METHODS All studied specimens are kept in the private herbaria of the collectors, designated by '(h)' in the specimens list below, except the holotype which is deposited in LG. Microscopical examination was done by examining hand-made sections in water or lactophe- nol-cotton blue with a Zeiss Photomikroskop at a mag- nification of x 2000, with or without phase contrast. Drawings were prepared using a drawing tube. The nomenclature of the hosts follows DIEDERICH & SERUSIAUX (2000) . RESULTS Cladoniicola Diederich, van den Boom & Aptroot gen. nov. Conidiomata lichenicola, pycnidia, stromati- ca, fusca, subglobosa, non ostiolata ; paries cellu- lis ellipsoideis ; setae nullae. Conidiophora nulla. Cellulae conidiogenae hyalinae, aseptatae, ellip- soideae, ampulliformes vel irregulares, apice contractae, holoblasticae. Conidia abundanti a,