first report on freshwater crab species (potamon bilobatum) in the altitudes of guilan (lakan area)

guilan province is located in south and south-west of the caspian sea. guilan is one of the richest and the most humid region in the country due to suitable climate, ample rainfall and many water sources (springs, rivers, creeks,..),. despite the prevailing favorable conditions, limnological studies, especially in the mountainous regions of this province are limited. a limnological study was conducted in the lakan area from march to june in 2008. macrobenthos were sampled from the freshwater stream that were mostly composed of freshwater crabs. the samples were transported to the natural history museum in frankfurt, germany, and the crab species was identified as potamon bilobatum belonging to family potamidae. the physico-chemical characteristics of water and the study area have been recorded.