Ontogeny of two gall-forming eriophyoid mites from Hainan Island, China (Acari: Eriophyoidea)

Two gall-forming eriophyoid mite species from Hainan Island (China) were found during field surveys in 2025. They are Acerimina tiliaceae Mohanasundaram & Sharma, 1984 rec. nov. on Hibiscus tiliaceus L. (Malvaceae) and Aceria blachiae sp. nov. on Blachia siamensis Gagnep. (Euphorbiaceae). The adult sexes and immature stages are described and illustrated for two species. We provided the mitochondrial cox1 gene sequences for Aceria blachiae sp. nov.