Original paper
A revision of Verticillium sect. Prostrata I. Phylogenetic studies using ITS sequences
Zare, R.; Gams, W.; Culham, A.
Nova Hedwigia Band 71 Heft 3-4 (2000), p. 465 - 480
40 references
published: Nov 24, 2000
ArtNo. ESP050007103012, Price: 29.00 €
Abstract
The anamorph genus Verticillium is extremely heterogeneous, comprising members of the Phyllachorales and Hypocreales, among the latter particularly the Clavicipitaceae. In view of vast biological differences (plant pathogens vs. parasites of fungi, insects, nematodes, and rotifers, which are often valuable in biological control), a subdivision into more natural entities is needed. A representative selection of strains available at CABI Bioscience and Centraalbureau voor Schimmelcultures was examined morphologically, and sequences ofthe ITS regions of nrDNA were analysed phylogenetically. Four clades are sharply delimited: Clade A comprises the type species of the genus, V. luteo-album, and members of Verticillium sect. Nigrescentia, which all have consistently erect conidiophores and are probably affiliated with the Phyllachorales. The large clade B contains species with white fluffy colonies lacking any resting structures; the most important members are the aggregates of V. lecanii with cylindrical and V. psalliotae with falcate conidia. Thus both entomogenous and fungicolous taxa are comprised in this clade. Cordyceps militaris belongs to this clade as do Aphanocladium aranearum and A. dimorphum; the latter taxon merges strains with exclusively short, evanescent ‘aphanophialides’ with those showing typical aculeate phialides. On the other hand, the type species of the genus Aphanocladium, A. album, is just distantly related to this clade. Teleomorphs of V. lecanii and 'Cephalosporium' lanosoniveum belong to Torrubiella, a genus that is scarcely distinct from Cordyceps. Clade C comprises a few taxa around V. balanoides, endoparasites of nematodes with balanoid to conoid and distally adhesive conidia. Clade D comprises mainly parasites of nematode eggs or cysts, which in the typical case produce dictyochlamydospores. These taxa were previously classified in the separate genus Diheterospora. A subclade contains the parasites of bdelloid rotifers classified in Rotiferophthora. The necessary nomenclatural conclusions will be drawn in a subsequent paper, when additional DNA portions have been sequenced.
Keywords
Hyphomycetes • phylogeny • morphology • classification • teleomorph connection