Mesostigmatid mites are one of the large group of Arthropods with world distribution which are found in all places. These mites are important because of their feeding on arthropods and other invertebrates that affect human and animal life. These Mites have close relation with different kinds of arthropods such as some hymenopterans. Ants form colonies which alter the available nutrients, texture, moisture, and temperature of the surrounding soil to suit their environmental needs. This efficiency of ants causes the attraction of different kinds of arthropods such as mites. To evaluate the mesostigmatid mites fauna associated with ants in Chaharmahal va Bakhtiari Province, sampling of the of ant nest from this province was conducted during 2015-2018. For sampling ants and soil of their nest collected by pence and shovel and was placed within the plastic bag. Necessary information such as geographical location (with GPS), name of location, date, habitats and other important data were recorded. Then samples were transferred to the laboratory and placed within the Berlese funnel for mite extraction. After 72 hours, mites fall down into the alcohol solution (70%). These samples were separated using appropriate needles and cleared in acid lactic (80%) at 50 °C and mounted into Hoyer medium as permanent microslides. The species which marked with strike are new for mite fauna of Chaharmahal va Bakhtiari Province. Identified species are as fallow:
Antennoseius (Antennoseius) bacatus Athias-Henriot, 1961; Antennoseius (Antennoseius) masoviae (Sellnick, 1943); Arctoseius cetratus (Sellnick, 1940); Arctoseius pristinus* Karg, 1962; Arctoseius semiscissus* (Berlese, 1892); Gamasellodes bicolor (Berlese, 1918); Iphidonopsis minutus* (Halbert, 1915); Iphidonopsis pulvisculus* (Berlese, 1921); Protogamasellus scuticalis Genis, Loots & Ryke, 1967.