Studies On Molecular Systematics Of The Genus Conidiobolus And Its Resource In China

Conidiobolus is one of the most important genus, and has a special systematic position in the phylum Entomophthoromycota. The Conidiobolus is a key decomposer in ecosystem, and some species can be used as the agents for controlling pest. From November2008to April2009, more than100Conidiobolus isolates from Anhui and Shandong provinces were isolated by Wang et al., and4new records of Conidooblus in China were published. To investigate the species diversity in the genus Conidiobolus from China and provide much more materials for systematic research, an efficient method improved by our team was used to isolate Conidiobolus isolates from Nature Reserves in Northeast, East, Central, South and Southwest of China. It is difficult to identify exactly the Conidiobolus strains at species level only based on the morphological character for its high heterogeneity and simple morphological structure. Recent studies showed that Conidiobolus adiaeretus Drechsler produced either microconida or capilliconida, which means that the division of three subgenera in the genus Conidiobolus is unreasonable. Some new developed classification features combined with molecular method should be used to identify Conidiobolus strains and to clarify phylogenetic relations within the genus Conidiobolus. In this research, we will exactly identify the Conidiobolus strains isolated from China, revise the King’s classification and resolve the taxonomic placement of three subgenera based on the new taxonomic characters (the maximum growth temperature and the average numbers of nucleus in primary conidia), important morphological features and nucleotide sequence data from multiloci.By comparing the maximum growth temperature among different Conidiobolus strains of the same species and among different Conidiobolus species, each species possessed a stable and specific maximum growth temperature, which can be distinguishing Conidiobolus species. The optimum growth temperature showed variation within a single species and obvious overlap between species, which are of little value in taxonomy. By comparing the average numbers of nucleus in primary conidia among different Conidiobolus strains of the same species and among different Conidiobolus species, each species had similar average numbers of nucleus in primary conidia, which are of important taxonomic value. We also found that the average numbers of nucleus in primary conidia had proportional relations with the size of primary conidia.Based on the molecular phylogenetic analysis of4gene loci:nuc-LSU, mt-SSU, EF-la and RPB2, a high level of heterogeneity was detected in the genus Conidiobolus. Combined far gentic distance among every clade in phylogenetic tree and the stable morphylogical character of the type of secondary conidia production, three subgenera in the genus Conidiobolus were rised to the status of the genus. A phylogenetic analysis assigned the Conidiobolus strains to three main lineages corresponding to the restored genus Delacroixia Sacc.&P. Syd., the estabished newly genus CapillidiobolusY. Nie&B. Huang and the emended genus Conidiobolus Brefeld. Clade I consists of four subgroups incuding subgroup A, subgroup B, subgroup C and subgroup D corresponding to the genus Delacroixia with microconidia, Conidiobolus iuxtagenitus, two Conidiobolus species and three small conidial species, respectively. The species from subgroup B, subgroup C and subgroup D do not produced microconidia and located at the base of the Clade I, and were put in Conidiobolus sensu lato. Although C. adiaeretus and C. bangalorensis Srin.&Thirum. formed a independent clade in the genus Capillidiobolus, they shared closer phylogentic relationship with Capillidiobolus than the species from other two genera. Therefore, these two species should classificated into the genus Capillidiobolus while C. adiaeretus could produce both microconidia and capilliconidia. The King’s classification was revised based on molecular data and two new taxonomic features.8homonyms in Conidiobolus were restored as species level,4of them were combined into the new genus. They are Capillidiobolus rugosus (Drechsler) Y. Nie&B. Huang, Delacroixia lichenicola (Srin.&Thirum.) Y. Nie&B. Huang, D. megalotocus var. indicus (Srin.&Thirum.) Y. Nie&B. Huang, D. mycophagus (Srin.&Thirum.) Y. Nie&B. Huang, Conidiobolus nodosus Srin.&Thirum., C. terrestris Srin.&Thirum., C. undulates Srin.&Thirum., C. parvus Drechsler.15new combinations were made i.e. Delacroixia macrosporus (Srin.&Thirum.) Y. Nie&B. Huang, D. mycophilus (Srin.&Thirum.) Y. Nie&B. Huang, D. khandalensis (Srin.&Thirum.) Y. Nie&B. Huang, D. humicola (Srin.&Thirum.) Y. Nie&B. Huang, D. polytocus (Drechsler) Y. Nie&B. Huang, D. incongruus (Drechsler) Y. Nie&B. Huang, D. firmipilleus (Drechsler) Y. Nie&B. Huang, D. megalotocus (Drechsler) Y. Nie&B. Huang, D. brefeldianus (Couch) Y. Nie&B. Huang, Capillidiobolus heterosporus (Drechsler) Y. Nie&B. Huang, C. lobatus (Srin.&Thirum.) Y. Nie&B. Huang, C. rhysosporus (Drechsler) Y. Nie&B. Huang, C. pumilus (Drechsler) Y. Nie&B. Huang, C. adiaeretus (Drechsler) Y. Nie&B. Huang, C. bangalorensis (Srin.&Thirum.) Y. Nie&B. Huang.During the investigation of Conidiobolus sensu lato in China in2009-2013, we have isolated more than250strains. Based on the careful morphological identification and molecular data,24taxa at species or variety level were described and illustrated. Among them,13taxa are new species or new variety. They are Capillidiobolus huoshanensis Y. Nie&B. Huang, C. flavosporus Y. Nie&B. Huang, C. sinensis Y. Nie&B. Huang, Conidiobolus guniujiangensis Y. Nie&B. Huang, C. bisporus Y. Nie&B. Huang, C. stilbella Y. Nie&B. Huang, Delacroixia lii Y. Nie&B. Huang, D. shitaiensis Y. Nie&B. Huang, D. dinghushanensis Y. Nie&B. Huang, D. langyashanensis Y. Nie&B. Huang, D. humberii Y. Nie&B. Huang, D. Drechslerii Y. Nie&B. Huang and Delacroixia coronatus var. longvillosus Y. Nie&B. Huang.3species are newly recorded for China. The3new records are:Capillidiobolus rhysosporus Drechsler, C. rugosus Drechsler, Conidiobolus lachnodes Drechsler.8species having been previously reported from China are redescribed and discussed, i. e. Conidiobolus osmodes Drechsler, C. thromboides Drechsler, C. macropapillatus C. F. Wang&B. Huang, C. iuxtagenitus S. D. Waters&Callaghan, Capillidiobolus heterosporus Drechsler, Delacroixia coronatus (Costantin) Sacc.&P. Syd., D. firmipilleus Drechsler and D. brefeldianus Couch. The strain RCEF5845needs to be instensively studied.