Taxonomic richness and host range of tropical Asian mussel‐associated mite assemblages (Acari: Unionicolidae) with a description of a new subgenus and species of parasitic mite from freshwater pearl mussels (Unionida: Margaritiferidae)

Abstract

Freshwater pearl mussels (Bivalvia: Margaritiferidae) are among the most imperiled groups of animals globally. While the parasites and symbionts of the Margaritiferidae are rather poorly known, these mussels were thought to be free of parasitic mites (Acari: Unionicolidae: Unionicola). Here, we report on the discovery of a mite species being associated with the endangered freshwater pearl mussel Gibbosula laosensis (Lea, 1863) from Myanmar. This species, Unionicola (Gibbosulicola) sella subgen. & sp. nov., morphologically resembles mites belonging to the subgenera Coelaturicola and Fulleratax (African and Southeast Asian groups, respectively). Our novel discovery expands the host range of Unionicola mites and reveals that all freshwater mussel families of the order Unionida host these aquatic mites. Our phylogenetic research and available published data reveal that the mussel-associated mite assemblage in Southeast and South Asia contains not less than 17 species and 8 subgenera. Currently, the regional taxonomic richness of this group seems to be largely underestimated. We found that mussel mites from Southeast Asia are narrow host specialists, which are known to occur in a single or a few closely related species belonging to one or two sister genera of freshwater mussels. Finally, our results indicate that mussel mites share generally restricted ranges and that their distribution patterns in Southeast Asia are largely congruent with the boundaries of biogeographic subregions delineated on the basis of phylogenetic studies of freshwater mussels. 614 | CHAPURINA et Al. 1 | INTRODUC TI ON The mantle cavity of freshwater mussels (order Unionida) is a home for a plethora of protists and metazoans, for example, ciliates, leeches, oligochaetes, mites, mayflies, dragonflies, crustaceans, and fishes (Brian &

A new species Unionicola (Dimockatax stat. rev.) haungthayawensis sp. nov. (Trombidiformes: Unionicolidae) from the freshwater mussel Lamellidens generosus (Gould, 1847) in Myanmar

“…We believe that the species-rich genus Unionicola needs to be divided into subgenera at least for the intrageneric classification purpose and definition. It was found in our previous work (Chapurina et al, 2021) that the clades of a reconstructed COI phylogeny correspond well to the subgenera established on the basis of morphological data. Unionicola haungthayawensis sp.nov.…”

“…For morphological research, mites were prepared with Faure-Berlese's mounting medium as described in our previous work (Chapurina et al, 2021) with minor clarifications: specimens of Dimockatax stat. rev.were incubated at 60°C in 8% KOH for 40 min before preparation.…”

“…DNA extraction, gene amplification and sequencing were performed as described in our earlier work (Chapurina et al, 2021). For phylogenetic analyses, we used 13 in-group COI sequences.…”

“…An integrative approach applied in our previous research revealed the presence of seven subgenera in Southeast Asia (Chapurina et al, 2021), including several putative new subgenera and species according to the morphology and DNA sequence data. The Southeast Asian species recovered by us share narrow host ranges.…”

“…The Southeast Asian species recovered by us share narrow host ranges. It was indicated that the most species-rich mite assemblages in Southeast Asia are associated with taxa belonging to the freshwater mussel tribe Lamellidentini (Chapurina et al, 2021). Recently, one new subgenus and several new species of parasitic mussel-associated water mites were described from this region (Chapurina et al, 2019;.…”