Morphological and ontogenetic characteristics of Eustigmaeus pinnatus (Kuznetsov) (Trombidiformes: Stigmaeidae)

The morphology and ontogeny of Eustigmaeus pinnatus (Kuznetsov) (Trombidiformes: Stigmaeidae) are described based on specimens collected from soil and litter in Türkiye. All active developmental stages, including larva, protonymph, deutonym ph, tritonymph and adults, are exa mined in detail. The tritonymphal stage, which has rarely been reported in the genus, is documented and characterized. Diagnostic morphological features of each stage are provided, with particul ar emphasis on the development of idiosomal shields, coxisternal organization, a nd leg and gnathosomal setati on, as well as aggenital c onfiguration. Ontogenetic changes in setation are analysed, and their taxonomic significance is discussed. Comparative assessments of E. pinnatus with E. jiangxiensis Hu, Chen & Huang and E. turcicus Doğan & Ayy ıldız are also presented. The results contribute to a better understanding of character development within the genus. Key words: Mite, Raphignathoidea, juveni le instar, tritonymph, compar ative morphology, ontogenetic transformation