Pergamasus

 Every once in a while I have a crazy urge to deep dive into a new neglected taxon. Sometimes I resist. 

Back in lockdown I listened to an excellent online talk on mites, and since I regularly get them in vacuum samples, I was tempted, but managed to resist. Over the stormy weekend I was clearing a backlog of samples from the past year and in one came across this chunky red-ish mite. Given the weather, I took photos and posted them on the excellent Facebook Soil Biodiversity UK group asking for help. One of the experts there was able to identify it as a male Pergamasus spp. (Family Parasitidae). I'm very grateful, but I'm still not planning on working on mites (or Thrips, which are easier) very often. 

Pergamasus (suborder Mesostigmata, family Parasitidae) is a species-rich genus of soil-dwelling predatory mites. They are key apex micro-predators within the soil food web, primarily distributed across the Holarctic region. Relatively large for soil mites, usually ranging from 0.8-1.5 mm in length. They are typically well-sclerotized with a characteristic yellowish-brown to dark reddish-brown chitinous body. Broadly oval, somewhat dorsoventrally flattened, with robust legs adapted for rapid movement and grasping prey. Adults possess a large, rigid dorsal shield (single, continuous plate covering the back) or a deeply divided schizodorsal shield depending on the species. Females possess a distinct, triangular or acuminate genital shield (epigynium) flanked by metasternal shields. Male leg II is heavily modified into a grasping organ with pronounced skeletal spurs and apophyses used during mating. The chelicerae feature a modified spermatotreme for sperm transfer. Found in soil & litter layers, both nymphs and adults are fast-moving, voracious generalist predators feeding on a wide variety of soil micro-invertebrates. They use their powerful, chelate chelicerae to puncture prey and suck out bodily fluids.

Bhattacharyya, S.K. (1963) A revision of the British mites of the genus Pergamasus Berlese s. lat. (Acari: Mesostigmata). Trustees of the British Museum (Natural History).