Confocal autofluorescence microscopy revealed the fine morphology of the amber preserved mite Congovidia glesoconomorphi sp. nov. (Acari: Hemisarcoptidae) phoretic on a mycterid beetle

We examined three astigmatic mite specimens phoretic on the beetle Glesoconomorphus ekaterinae from Eocene Rovno amber. Due to the precious nature of this amber piece, housing the name-bearing holotype of the host beetle, traditional trimming for the application of high-resolution imaging techniques at small focal distances was unfeasible. To overcome this challenge, we employed a combination of confocal microscopy relying on the autofluorescence properties of the mite chitinous exoskeleton and long working distance / water immersion objectives. This innovative approach successfully resolved the minute mite features from a considerable distance (700 μm). Based on these data, we describe many taxonomically important characters and identify these mites as a new species, Congovidia glesoconomorphi sp. nov., within the family Hemisarcoptidae. This represents the first fossil record for the mite family. Additionally, we provide a key for phoretic deutonymphs of all known species of Congovidia. As larvae of many extant Eurypinae live in subcortical spaces of decomposing tree trunks, we suggest that the mite C. glesoconomorphi similarly occupied subcortical niches in decayed wood and utilized adult beetles of G. ekaterinae for dispersal.