Revisiting Metarhizium and the description of new species from Thailand

Abstract

Over the last two decades the molecular phylogeny and classification of Metarhizium has been widely studied. Despite these efforts to understand this enigmatic genus, the basal lineages in Metarhizium are still poorly resolved. In this study, a phylogenetic framework is reconstructed for the Clavicipitaceae focusing on Metarhizium through increased taxon-sampling using five genomic loci (SSU, LSU, tef, rpb1, rpb 2) and the barcode marker ITS rDNA. Multi-gene phylogenetic analyses and morphological characterisation of green-spored entomopathogenic Metarhizium isolates from Thailand and soil isolates of M. carneum and M. marquandii reveal their ecological, genetic and species diversity. Nineteen new species are recognised in the Metarhizium clade with narrow host ranges: two new species are found in the M. anisopliae complex – M. clavatum on Coleoptera larvae and M. sulphureum on Lepidoptera larvae; four new species are found in the M. flavoviride complex – M. biotecense and M. fusoideum on brown plant hoppers ( Hemiptera ), M. culicidarum on mosquitoes, M. nornnoi on Lepidoptera larvae; three new species M. megapomponiae, M. cicadae, M. niveum occur on cicadas; five new species M. candelabrum, M. cercopidarum, M. ellipsoideum, M. huainamdangense M. ovoidosporum occur on planthoppers, leafhoppers and froghoppers ( Hemiptera ); one new species M. eburneum on Lepidoptera pupae; and four new species M. phuwiangense, M. purpureum, M. purpureonigrum, M. flavum on Coleoptera . Of these 19 new species, seven produce a sexual morph ( M. clavatum, M. eburneum, M. flavum, M. phuwiangense, M. purpureonigrum, M. purpureum, and M. sulphureum ) and asexual morphs are found in the remaining new species and also in M. sulphureum, M. purpureonigrum and M. purpureum. Metarhizium blattodeae, M. koreanum and M. viridulum are new records for Thailand. An alternative neotype for Metarhizium anisopliae is proposed based on multi-gene and 5′ tef analyses showing that CBS 130.71 from Ukraine is more suitable, being from a much closer geographical location to Metchnikoff’s Metarhizium anisopliae. This isolate is distinct from the neotype of Metarhizium anisopliae var. anisopl...

Metarhizium: jack of all trades, master of many

“…Many of these are rare locally distributed specialists. Thus, a 2020 paper [ 107 ] describes 19 new species with narrow host ranges in Thailand, seven of which produce a sexual morph.…”

“…Thus, sex, or the lack thereof, plays an important role in pathogen strategies and the risks associated with genetic engineering. Molecular phylogenetic analyses of Metarhizium have shown that sexually reproductive Metarcordycep forms are distributed among clades comprised of Metarhizium isolates assumed to be reproducing asexually [ 28 , 29 , 107 ]. The requirements for sexual reproduction in the genus remain enigmatic, but observations suggest that sexual reproduction, as evidenced by teleomorphic forms (note that a teleomorph is the sexual stage of a fungus), is restricted to a narrow range of host insects in geographically restricted regions [ 107 , 208 ].…”

“…Molecular phylogenetic analyses of Metarhizium have shown that sexually reproductive Metarcordycep forms are distributed among clades comprised of Metarhizium isolates assumed to be reproducing asexually [ 28 , 29 , 107 ]. The requirements for sexual reproduction in the genus remain enigmatic, but observations suggest that sexual reproduction, as evidenced by teleomorphic forms (note that a teleomorph is the sexual stage of a fungus), is restricted to a narrow range of host insects in geographically restricted regions [ 107 , 208 ]. By contrast, asexual forms tend to occupy extensive geographical distributions and a broader spectrum of niches, particularly the soil environment [ 172 , 208 ].…”

Novel taxa and species diversity of Cordyceps sensu lato (Hypocreales, Ascomycota) developing on wireworms (Elateroidea and Tenebrionoidea, Coleoptera)

“…Sung et al (2007) revised it to O. jiangxiensis only based on the original morphological description. The species is closely similar to Metarhizium purpureonigrum, a recently-described species from Thailand (Mongkolsamrit et al 2020). Future studies are warranted to clarify its taxonomic placement.…”

“…Notes. According to the description and pictures provided (Mongkolsamrit et al 2020), the species is probably a synonym of O. jiangxiensis, a traditional Chinese medicinal mushroom (Zha et al 2018, also see O. jiangxiensis below). Hosts of the species, which were recorded as Coleoptera larvae, are Elateridae larvae (Campsosternus sp.…”