Morphological ontogeny provides critical insight into character polarity, stage-specific diagnostic traits, and evolutionary relationships in Phytoseiidae. To advance understanding of these aspects, we reared Phytoseius huaxiensis Xin, Liang & Ke under controlled laboratory conditions and documented its complete developmental stages—larva, protonymph, deutonymph, and adult. Each stage is described and illustrated, with emphasis on diagnostic features and ontogenetic changes in dorsal shield structure, idiosomal and leg setation, and gnathosomal morphology. Comparative analysis with other phytoseiid taxa reveals both conserved and divergent traits, refining genus-level diagnoses and contributing to phylogenetic interpretation across the family.

The genus Neoseiulus in Shanxi Province is reviewed and seven species are recorded from the province. Four of these are redescribed and detailed taxonomic information are provided. Neoseiulus paraki (Ehara) is recorded for the first time in China and Neoseiulus neoreticuloides (Liang and Hu) is considered a new junior synonym of Neoseiulus bicaudus (Wainstein). Additionally, a diagnostic key to the known species of Neoseiulus in Shanxi is provided.

A new species of mite, Amblyseius taiguensis Liu, Ma & Fan, sp. nov. (Acari: Phytoseiidae), has been recently discovered from Setaria viridis (L.) P. Beauv. (Poaceae) in Taigu County, Shanxi Province, China. The morphology of this new species is described in detail for all life stages, including larva, protonymph, deutonymph and adult female and male. A comparison of the morphology of A. taiguensis sp. nov. with other related species in the genus Amblyseius Berlese has been conducted. This new finding contributes to the diversity of phytoseiid mites in China and the studies of morphological changes could have implications for the understanding of the developmental and evolutionary biology of Amblyseius.

Chyzeriidae Womersley, 1954, is a family of trombidiform mites characterized by unique body structures and habits, though it has not been well studied. A new genus and species, Cretachyzeria macrosetagen. et sp. nov., in the subfamily Pteridopinae of Chyzeriidae, found in Cretaceous amber in Myanmar, provides the first formally described fossil species in this family. A phylogenetic study of Chyzeriidae based on postlarval morphology supported the morphological classification. The dorsal setae of Cretachyzeria macrosetagen. et sp. nov. are extremely long and dense, resembling the quills of a porcupine. This unusual morphological structure likely served specific biological functions. We hypothesize that these long setae functioned as a specialized defense, protecting the fragile abdomen and aiding in predator deterrence in its complex environment. Given the geological time frame of this fossil mite and the wide distribution of extant Chyzeriidae, we propose that the family existed prior to the breakup of Pangaea.