Two new species of the genus Acherontiella (Collembola, Hypogastruridae) from caves of the Alborz and Kopet Dagh mountains in Iran

Two new subterranean species of the genus <i>Acherontiella</i> Absolon, 1913 from Iran are described, illustrated, and morphologically differentiated from similar species. <i>Acherontiella nezamdoosti</i> <b>sp. nov.</b> has larger distribution range covering caves of North Khorasan, Razavi Khorasan, and Tehran provinces, while <i>A. palaciosi</i> <b>sp. nov.</b> is probably restricted to Moghan Cave in Razavi Khorasan province. Both new species are characterized by absence of eyes, PAO, empodium, furca, and retinaculum. <i>Acherontiella nezamdoosti</i> <b>sp. nov.</b> is distinguished from other species by having two small anal spines, Th II-III with setae m1, m4, and m5, and four thickened anterior setae on the labrum. <i>Acherontiella palaciosi</i> <b>sp. nov.</b> is characterized by bearing two medial setae in the anterior row of the labrum thickened into spines and apically dentate, and by the absence of setae m3 on Th I and p3 on Th II-III. An updated key and a table summarizing diagnostic characters of world species of the genus <i>Acherontiella</i> are provided.