A new species of Pachyseius Berlese (Acari: Pachylaelapidae) from South Siberia (Russia), with a key to the species known from Asia Marchenko, Irina I. Zootaxa 2015 3905 2 221 232 8XNHC [730,865,799,825] Arachnida Pachylaelapidae Pachyseius GBIF Animalia Mesostigmata 9 230 Arthropoda genus    1. Anterior margin of sternal shield with a pair of horn-like projections anterior to seta St1; presternal shields absent; posterior part of peritermatal shields fused to exopodal shields IV....................................................... 2  - Anterior margin of sternal shield without horn-like projections; presternal shields present; posterior part of peritermatal shields free, abutting exopodal shields IV........................................................................ 5   2. Dorsal idiosoma with 29 pairs of slightly spatulate setae ( z1absent).................  P. cavernicola Ishikawa, 1989; Japan  - Dorsal shield with 30 pairs of acicular setae................................................................. 3   3. Ventri-anal shield with four pairs of pre-anal setae ( Jv1-Jv3, Zv2).................  P. sinicus Yin, Lu & Lan, 1986; China  - Ventri-anal shield with at most three pairs of pre-anal setae..................................................... 4   4. Epistome triangular, with narrow distal projection; small sclerites between peritrematal and ventri-anal shields present; cir- cum-anal setae longer than anus.............................................  P. chenpengi Ma & Yin, 2000; China  - Epistome subrectangular, with anterior margin regularly rounded; small sclerites between peritrematal and ventri-anal shields absent; circum-anal setae as long as anus..............................  P. huanrenensis Chen, Bei & Gao, 2009; China   5. Ventri-anal shield with three pairs of pre-anal setae ( Jv1-Jv3).................................................. 6  - Ventri-anal shield with two pairs of pre-anal setae ( Jv1, Jv2).................................................... 7   6. Marginal and ventral soft integument with eight pairs of setae (including r6)..........................................................................................  P. humeralis Berlese, 1910; Europe; Canary Islands, Caucasus  - Marginal and ventral soft integument with six pairs of setae (including r6).....  P. masani Özbek & Halliday, 2014; Turkey   7. Tarsus II with at most three spur-like setae; presternal area weakly reticulate; ventri-anal shield suboval, slightly widened ante- riorly.........................................................  P. angustus Hyatt, 1956; Europe; Iran, Caucasus  - Tarsus II with one or two spur-like seta; one pair of sclerotised presternal shields present; ventri-anal shield subtriangular form with obvious anterolateral expansion...................................................................... 8   8. Tarsus II with two spur-like setae, marginal and ventral soft integument with 11 pairs of setae; trochanter I with five setae....................................  P. anisimovi  sp. nov.; Russia: South Siberia (Altai, West and East Sayan Mountains)  - Tarsus II with one spur-like setae, marginal and ventral soft integument with 12–19 pairs of setae, trochanter II with six setae.................................................................................................... 9   9. Marginal and ventral soft integument with 12 pairs of setae, ventri-anal shield with expanded anterolateral margins abutting metapodal shields; peritrematal shield at level of stigmata is greatly expanded..................................................  P. orientalis Nikolsky, 1982; Russia: south of Far East, South Siberia (East Sayan and Altai Mountains); China  - Marginal and ventral soft integument with 19 pairs of setae, ventri-anal shield not conspicuously expanded anterolaterally;