Four new species of Trichoderma in the Harzianum clade from northern China

Abstract

The <i>Harzianum</i> clade of <i>Trichoderma</i> comprises many species, which are associated with a wide variety of substrates. In this study, four new species of <i>Trichoderma</i>, namely <i>T. lentinulae</i>, <i>T. vermifimicola</i>, <i>T. xixiacum</i>, and <i>T. zelobreve</i>, were encountered from a fruiting body and compost of <i>Lentinula</i>, soil, and vermicompost. Their colony and mycelial morphology, including features of asexual states, were described. For each species, their DNA sequences were obtained from three loci, the internal transcribed spacer (ITS) regions of the ribosomal DNA, the gene encoding the second largest nuclear RNA polymerase subunit (RPB2), the translation elongation factor 1-α encoding gene (TEF1-α). The analysis combining sequences of the three gene regions distinguished four new species in the <i>Harzianum</i> clade of <i>Trichoderma</i>. Among them, <i>T. lentinulae</i> and <i>T. xixiacum</i> clustered with <i>T. lixii</i>, from which these new species differ in having shorter phialides and smaller conidia. Additionally, <i>T. lentinulae</i> differs from <i>T. xixiacum</i> in forming phialides with inequilateral to a strongly-curved apex, cultural characteristics, and slow growth on PDA. <i>Trichoderma vermifimicola</i> is closely related to <i>T. simmonsii</i>, but it differs from the latter by producing phialides in verticillate whorls and smaller conidia. <i>Trichoderma zelobreve</i> is the sister species of <i>T. breve</i> but is distinguished from <i>T. breve</i> by producing shorter and narrower phialides, smaller conidia, and by forming concentric zones on agar plates. This study updates our knowledge of species diversity of <i>Trichoderma</i>.