Thyreophagus tauricus sp. n., a New Subcortical Mite Species (Acari: Acaridae), with a COX1 DNA Sequence Analysis of Several Economically Important Species of Thyreophagus †

SIMPLE SUMMARY: In recent years, there has been a growing interest in finding sustainable and environmentally friendly solutions to combat agricultural pests while minimizing the adverse impacts of chemical pesticides. Species of the genus Thyreophagus have emerged as a valuable asset in this pursuit. These mites are utilized as factitious prey for the mass rearing of predatory mites. Predatory mites, in turn, play a crucial role in biological pest control—they feed on a variety of agricultural pests such as spider mites, thrips and other small arthropods that harm crops. Despite their significance, we do not know much about Thyreophagus mites because many species live in hidden habitats and are difficult to study. As part of our survey, we discovered a new species, Thyreophagus tauricus, and provide detailed descriptions of its different life stages. Genetic sequencing was also performed to identify this new species and compare it with others: Thyreophagus corticalis (broadly distributed Palearcic species), Th. calusorum, Th. entomophagus (economically important factitious prey mites). We also correct some mistakes in mite identification, particularly the economically important species Th. entomophagus, which can be crucial for future studies and biocontrol applications. ABSTRACT: As part of a survey of the subcortical astigmatic mites of Crimea, we discovered a new sexual acarid species, Thyreophagus tauricus sp. n. This species was cultured in the laboratory to correlate the adult and deutonymphal stages. Using specimens obtained by these rearing experiments, we provide a detailed description of Th. tauricus (light microscopy, SEM) based on females, males and heteromorphic deutonymphs. Furthermore, to facilitate molecular identification, the entire COX1 gene was also sequenced for this and three other Palearctic species reared in the lab as pure cultures. Adults of Th. tauricus sp. n. are distinct among all other species of the genus by the presence of flattened, button-shaped or minute spiniform setae s III and IV, which are well-developed spiniform in all other known species of Thyreophagus. Heteromorphic deutonymphs of Th. tauricus are distinct from all other species of Thyreophagus by the presence of well-developed setae cm on the dorsal part of the subcapitular remnant (absent all other species). Th. tauricus is morphologically very similar to Th. corticalis; however, COX1 K2P distances between these two species were large, 19.8%. COX1 K2P distances between Th. tauricus and other species (Th. entomophagus, Th. “entomophagus” NC 066986.1, Th. calusorum, Th. corticalis) ranged between 20.1 and 24.3%. We show that the GenBank sequence of Th. “entomophagus” from China (NC 066986.1) was probably misidentified.