Updating taxonomy of Conidiobolus sensu lato: Proposal of a new family, a new genus, 23 new species and two new combinations
Y Nie, H Zhao, MH Zhang, HB Lee, Y Chang, XY Liu, B Huang
Abstract
Conidiobolus sensu lato entomophthoroid fungi comprise one of the most species-rich, diverse, and ecologically significant lineages in entomophthoroid fungi. Primarily saprophytic on fallen leaves and other organic debris, these fungi are also pathogenic to insects and can occasionally infect mammals, including humans, causing conidiobolomycosis. The recent increase in human infections underscores the urgency of a comprehensive taxonomic reassessment to understand disease origins better, develop preventive measures, and harness biocontrol potential. Molecular analyses have revealed the polyphyletic nature of this group, prompting its reclassification into three families and five genera. Although this revision provides clarity, the precise phylogenetic placement of Microconidiobolus remains unresolved. We herein performed a comprehensive phylogenomic analysis of Conidiobolus s.l., incorporating 43 newly sequenced genomes and divergence-time estimates based on multiple loci (nucLSU, EFL, and mtSSU). The results indicate that family-level lineages diverged approximately 281 million years ago (Mya), highlighting the deep evolutionary history of these fungi. Microconidiobolus was robustly placed as a sister group to Conidiobolaceae, with an estimated divergence time around 279 Mya, and was consequently raised to family rank. Integrating these molecular findings with morphological data, we propose an updated classification of four families (Capillidiaceae, Conidiobolaceae, Microconidiobolaceae, and Neoconidiobolaceae) and six genera (Azygosporus, Callaghania, Capillidum, Conidiobolus sensu stricto, Microconidiobolus, and Neoconidiobolus). Twenty-three new species (two in Capillidium, 16 in Conidiobolus s.s., and five in Neoconidiobolus) were described from China, and two new combinations were put into Callaghania. Additionally, comprehensive morphological keys to facilitate species identification were provided. Overall, this study constitutes a monographic treatment of Conidiobolus s.l., offering crucial insights into their taxonomy and into the early diversification of terrestrial fungi.