LABOULBENIALES - Agentschap voor Natuur en Bos

1. LABOULBENIALES1.1. DEFINITION OF LABOULBENIALESLaboulbeniales include over 2000 species in 141 genera (SANTAMARIA, 1998; KIRKet al., 2001; WEIR & BLACKWELL, 2005) of obligate, ectoparasitic fungi, which liveassociated with arthropods, mostly true insects. Laboulbeniales have nomycelium; their thalli are small and of determinate growth, bearing antheridiaand perithecia on a receptacle with appendages (TAVARES, 1985). Only sexualstages are known. Laboulbeniales are host-specific (THAXTER, 1896; SCHELOSKE,1969; TAVARES, 1985; MAJEWSKI, 1994; DE KESEL, 1996, 1997).The knowledge on Laboulbeniales is rather recent and has increased slowly.Large parts of their biodiversity are still unknown and many questions stillunresolved.1.2. HISTORICAL BACKGROUNDIn the 1840s, two French entomologists, Joseph Alexandre Laboulbéne andAuguste Rouget, did the earliest observations on Laboulbeniales resulting in afirst publication on the Laboulbeniales (ROUGET, 1850, ref. in TAVARES, 1985). Atfirst, the structures on Brachinus (Coleoptera, Carabidae) were thought to besupernumerary antennal segments. ROUGET (1850, ref. in TAVARES, 1985)suggested that they were living organisms. The recognition as fungi came in1852 and the genus Laboulbenia was raised within the Pyrenomycetes – anextensive group of Ascomycetes (ROBIN, 1853). Later on, specimens onwingless dipteran parasites of bats were still mistakenly described asArthrorhynchus, an acanthocephalan worm, by KOLENATI (1857).MAYR (1853) thought that the „hairlike structures‟ on Nebria (Coleoptera,Carabidae) were chitinous. Suggesting that they were outgrowths of theinsect‟s integument, he noticed differences between those structures onyounger and older beetles. On older individuals, there was always a variableswelling on the hair, whereas no such swelling was present on the hair ofyounger beetles.PEYRITSCH (1871) made extensive observations on the structure anddevelopment of the housefly Laboulbenia (L. muscae Peyr.). PEYRITSCH (1871)redescribed Arthrorhynchus as Laboulbenia nycteribiae Peyr. He laterestablished the family Laboulbeniaceae in the Ascomycetes (PEYRITSCH, 1873)and laid a solid foundation for our understanding of the biology ofLaboulbeniales (PEYRITSCH, 1875), based on observations of laboratory coloniesof houseflies and studies of Laboulbeniales in the field.A systematic study of the Laboulbeniaceae was begun by Roland Thaxter in1890, when he published his first in a series of papers describing hundreds ofnew species. In 1896, THAXTER‟S first monographic volume on theLaboulbeniaceae appeared. It was particularly a summary upon all previouswork (TAVARES, 1985). The monograph of Thaxter – five volumes, published in1896, 1908, 1924, 1926 and 1931 – constituted the basis for later studies of thegroup. Unfortunately Thaxter died only one year after the publication of theP a g e | 9