Gy. Liou et Ss. Tzean, PHYLOGENY OF THE GENUS ARTHROBOTYRS AND ALLIED NEMATODE-TRAPPING FUNGI BASED ON RDNA SEQUENCES, Mycologia, 89(6), 1997, pp. 876-884
Ribosomal DNA of 29 nematode-trapping fungi in the genera Arthrobotrys
, Dactylella, Duddingtonia, Geniculifera, Monamosporium, Nematoctonus,
and 5 nonpredacious, allied fungi in the genera Orbilia, Trichotheciu
m, Dactylaria, and Arthrobotrys was amplified by polymerase chain reac
tion and sequenced using universal primers. Phylogenetic analysis of 5
.8S rDNA using parsimony indicated that 28 clampless nematode-trapping
fungi were monophyletic and have evolved from a common ancestor. Clam
ped Nematoctonus robustus, having a Hohenbuehelia basidiomycetous tele
omorph, was phylogenetically distant and the predacious habit was gain
ed through convergent evolution. Nonpredacious Arthrobotrys, Dactylari
a, and Trichothecium species, despite having morphologically similar c
onidiogenous cells and conidia, actually were grouped in a genetically
distant region of the tree. Analysis of the more variable internal tr
anscribed spacer, ITS1 and ITS2, revealed that the 28 nematode-trappin
g fungi were separated into 4 clades, each with a unique trapping devi
ce. Phylogenetic analysis of rDNA of trapping fungi in this study indi
cated that trapping organs may reflect evolutionary relationship, and
appear more significant than conidiogenous cells and conidia for genus
and species delimitation. We suggest that the circumscription of the
Arthrobotrys-Dactyella-Monacrosporium complex be revised to provide a
natural classification system.