An expanded microsporidia species attribute database documents the extensive ecological and phenotypic diversity of these parasites

Abstract

Microsporidia are a group of parasites that exhibit vast morphological, ecological, and genetic diversity. To catalog this diversity, we previously generated a database of attributes for microsporidia species. Here we expand this database to include species described since 2021, previously missed descriptions, and provisional species defined by clustering GenBank 18S rRNA sequences, resulting in 1,795 species. Using these data, we describe when and where microsporidia have been reported, their hosts and host habitats, the tissues they infect, and their spore morphology. A phylogeny of 18S sequence clusters shows that closely related microsporidia tend to infect closely related hosts, such that sequence identity is predictive of host taxonomy. Clustering also reveals previously unappreciated genetic diversity within some named species, in particular the human pathogen Vittaforma corneae, suggesting that these may comprise multiple species. We have also generated a web portal through which new species information can be submitted, which will facilitate regular updates. This database provides a resource for systematic analysis of microsporidia properties and a reference for taxonomic descriptions. Author summary Microsporidia are parasites that infect animals from insects and fish to humans, and species vary enormously in the hosts they infect, the environments they occupy, and the appearance of their spores. This information has accumulated over more than 150 years of species descriptions scattered across thousands of publications. Here we expand a database that brings it together, adding species described in the last five years, older descriptions that had been missed, and species known only from DNA sequences in public repositories. The resulting database of nearly 1,800 species allows us to show when and where microsporidia have been discovered, which animals and tissues they infect, and how their spores vary in size and shape. Comparing sequences across species shows that closely related microsporidia tend to infect closely related hosts, so a parasite’s DNA alone suggests the kind of animal it infects. It also reveals that some described species, most notably the human eye pathogen Vittaforma corneae, contain far more genetic diversity than their names suggest and likely represent several distinct species. We also provide a web portal through which researchers can submit new species, providing a lasting resource for studying and classifying these parasites.