Taxonomy And Phylogeny Of Ophiocordyceps From Vietnam

Ophiocordyceps is a special large genus of Ophiocordycipitaceae,which is widely distributed around the world.The species composition and host types are extremely rich,and the morphological characteristics and ecological environment are complex and diverse.Up to now,a amount of species have not been discovered in Ophiocordyceps.In addition,there are many closely related species morphologically similar but genetically different in the genus of Ophiocordyceps.They are hidden under the species complex,with greatly underestimating the species diversity for a wide range of Ophiocordyceps taxa in Kingdom Fungi.Therefore,the genus of Ophiocordyceps may be one of the largest repositories of unrecorded species in Kingdom Fungi.With the continuous development of DNA molecular sequence technique and barcoding technological application in the classification of Cordyceps sensu lato,it is not surprising to unveil many mysterious species,and it is revealed that species complex is a common phenomenon in the genus of Ophiocordyceps.Nevertheless,many species of Ophiocordyceps are still hidden in nature,and there are still a large number of unrevised taxa in many complexes.Therefore,it is undoubtedly an important task in the taxonomy of fungi to take more samples from the genus,and combine morphology and phylogeny to solve the taxonomic problem of the genus.As its unique geographical location and climatic conditions,Vietnam is one of the countries with extremely rich biodiversity in the Southeast Asia,and the resources of Cordyceps sensu lato are also extremely rich.At present,more than 100 species of Cordyceps sensu lato are reported,but this is only the tip of the iceberg of Cordyceps sensu lato resources in Vietnam.In order to understand the situation of Cordyceps sensu lato resources in Vietnam,it is necessary to conduct in-depth investigation and research.This study focused on the species of Ophiocordyceps collected by our research group in Vietnam several times.Based on the previous research data,the phylogenetic framework of Ophiocordyceps was constructed by using five loci of nrSSU,nrLSU,tef-1?,rpb1 and rpb2.Combined with morphological and ecological characteristics,the species of Ophiocordyceps in Vietnam were identified and described in detail,and the taxonomic status of each species was clarified.Based on phylogenetic analysis and morphological characteristics,the taxonomic revision was carried out for the taxonomic errors or undetermined taxonomic positions in Ophiocordyceps.The main results are as follows:(1)A total of 176 taxon 4993 bp sequence data were obtained by five-gene phylogenetic analysis.The genus of Ophiocordyceps was divided into four main clades by ML and BI analysis,namely Hirsutella clade,Hymenostilbe clade,Ophiocordyceps sobolifera clade,and Ophiocordyceps ravenelii clade.Further,the Hirsutella clade was divided into six subclade,including Hirsutella sinensis,H.guyana,H.nodulosa,H.thompsonii,H.citriformis,and Hirsutella ant pathogen.(2)Based on phylogenetic analysis and morphological characteristics,the 18 species of the genus were identified,including 7 new species,8 newly recorded species from Vietnam and 3 known species.The phylogenetic position and phylogenetic relationship of each species were clarified.(3)According to the materials collected in this study,combined with molecular data and morphological characteristics,Ophiocordyceps.unilateralis KT3307 was reclassified as O.camponotimuri-leonardia,and O.myrmecophila MFLUCC162912 was reclassified as O.granospora.(4)all 18 species of Ophiocordyceps from Vietnam in this study were described and noted based on morphological and ecological characteristics.The seven new species including Ophiocordyceps hoanglienensis,O.puluongensis,O.pumatensis,O.chuyangsinensis,O.thanhhoaensis,O.pseudonutans and O.bidoupensis were described in the present paper.In addition,the following discussions were made in this paper:(1)By comparing the morphological characteristics of closely related species which were very similar to the appearance in this study,and combining with phylogenetic analysis,the importance of microscopic morphology and molecular evidence to uncover the cryptic species was discussed in the species complex.(2)Based on molecular phylogeny,morphology and ecology,the host relationship and functional morphology of Ophiocordyceps were analyzed,and the relationship between Ophiocordyceps and habitat and the host jump model were discussed.