New records of three Latrodectus species found in Khorasan province (Araneae: Theridiidae)

Three Threidiid spiders of the genus Latrodectus occur in Khorasan province: L.tredecimguttatus, L.pallidus, L.dahli. The three are described, their diagnostic featuresare illustrated, and taxonomic notes are given where possible. Spider bites are very common in these regions, so, further notes about the medical importance of thesespecies are given. A dichotomic key to the species of the genus Latrodectus is presented.