Two new myrmecophilous species of the genus Petalomium (Acari: Pygmephoroidea: Neopygmephoridae) Author Khaustov, Alexander A. text Zootaxa 2015 3999 4 549 559 journal article 10.11646/zootaxa.3999.4.5 6fffa172-7a0a-47b7-91d0-8b8b387792b3 1175-5326 244406 995D22E6-0E74-423B-84E1-6D218206F423 Petalomium reductus Khaustov sp. nov. ( Figs. 5–7 ) Description . FEMALE ( Figs. 5–7 ). Body weakly sclerotized. Length of idiosoma 305 (270–310), width 220 (215– 225). Gnathosoma ( Fig. 5 ). Similar with that of P. crossi sp. nov . , but dorsal cheliceral setae subequal and sparsely barbed. Lengths of gnathosomal setae: cha 20 (18–21), chb 21 (19–22), m 18 (18–20). Idiosomal dorsum ( Fig. 5 A). Only posterior part of prodorsum covered by anterior margin of tergite C, with 2 pairs of setae ( v 2 , sc 2), 1 pair of clavate and weakly barbed trichobothria ( sc 1) with rounded apex and 1 pair of round stigmata with transverse slitlike opening. Distinct oblique sclerotized line situated between bases of setae v 2 and sc 2. All dorsal plates smooth. Setae v 2 and sc 2 smooth, other dorsal setae distinctly barbed; setae h 2 densely covered by numerous and thin barbs (pubescent), other dorsal setae sparsely barbed. Setae sc 2 and e blunt-ended, other dorsal setae pointed. Posterior margin of tergite C weakly concave; posterior margin of tergite EF straight; posterior margin of tergite H with tongue-like elongation medially. Cupules ia on tergite D and ih on tergite H small, round. Lengths of dorsal setae: v 2 5 (5–6), sc 2 19 (18–20), c 1 85 (82–87), c 2 94 (89–96), d 100 (86–100), e 30 (29–32), f 125 (115–130), h 1 99 (91– 100), h 2 31 (29–32). Distances between setae: v 2 –v 2 75 (67–77), sc 2 –sc 2 88 (82–89), c 1– c 1 88 (82–89), c 1– c 2 47 (38– 48), d–d 94 (88–95), e–f 16 (13–17), f–f 88 (77–89), h 1– h 1 39 (32–40), h 1– h 2 23 (19–24). Idiosomal venter ( Fig. 5 B). All ventral plates smooth. Setae 1 b bifurcate. Setae ps 3 smooth, other ventral setae sparsely barbed. Ap1 well developed and joined with appr; ap2 weakly developed, thin, not joined with appr; appr and apsej well developed; appr without gap; ap3 weakly developed, straight, diffuse. Ap4 well sclerotized, long and joined with appo; apodemes 5 absent. Posterior margin of posterior sternal plate weakly convex in middle part. Posterior margin of aggenital plate weakly concave. Ags long, bell-like, pgs triangular, median genital sclerite not evident. Lengths of ventral setae: 1 a 61 (57–63), 1 b 38 (36–42), 2 a 59 (54–60), 2 b 74 (64–75), 3 a 47 (45–49), 3 b 53 (48–55), 3 c 45 (42–47), 4 a 43 (40–45), 4 b 50 (46–51), 4 c 48 (44–49), ps 1 42 (36–43), ps 2 25 (22–26), ps 3 16 (13–17). Legs ( Figs. 6 , 7 ). Leg setation as in P. crossi sp. nov . except absence of solenidion ω 2 of tibiotarsus I. Leg I ( Fig. 6 A) distinctly shorter and thinner than leg II. Tibiotarsus not thickened, without pretarsus and claw. Length of solenidia ω 1 16 (16–17)> φ 1 8 (7–8) < φ 2 11 (11–14); ω 1 and φ 2 finger-shaped, φ 1 clavate. Eupathidium tc” situated on long pinnaculum, tc’ on short pinnaculum. Setae dFe broadened, slightly curved at the tip. Setae l’Fe blunt-ended, smooth, v’Tr smooth, pointed, other leg setae (except eupathidia) pointed and sparsely barbed. Leg II ( Fig. 6 B). Tarsus with sickle-like, padded claws and large flipper-like smooth empodium. Solenidion ω 12 (12–13), fingershaped, solenidion φ 6 (6–7) weakly clavate. Setae v”Fe smooth, other leg setae sparsely barbed, pointed. Leg III ( Fig. 7 A) similar in shape and length with leg II. Claws and empodium of same shape as on tarsus II. Solenidion φ 6 (6–7) weakly clavate. All leg setae pointed and sparsely barbed. Leg IV ( Fig. 7 B). Tarsus long and thin, pretarsus short, with two small simple claws and small empodium. Solenidion φ 6 (6–7) weakly clavate. All leg setae pointed and sparsely barbed. MALE and LARVA unknown. Type material . Female holotype , slide No. AP 051214 /1 and 8 female paratypes from ants Myrmicaria distincta Santschi, 1925 , ETHIOPIA : Amhara Region, Bahir-Dar city, territory of the Bahir Dar Fisheries and other Aquatic Life Research Center, coast of lake Tana, 11º36,70'N , 037º22,36'E , 5 December 2014 , coll. A.A. Prokin. FIGURE 5 . Petalomium reductus Khaustov sp. nov . , female: A—idiosomal dorsum, B—idiosomal venter. FIGURE 6 . Petalomium reductus Khaustov sp. nov . , female: A—leg I in dorsal view, B—leg II in dorsal view. Etymology . The name of this new species refers to its unusual reduction of solenidion ω 2 and the claw on tibiotarsus I. Differential diagnosis . The new species is morphologically similar to P. endroedyi Mahunka, 1974 by the absence of the claw on tibiotarsus I. It differs from P. endroedyi by the absence of solenidion ω 2 (present in P. endroedyi ), solenidion φ 2 distinctly longer than φ 1 ( φ 1 and φ 2 subequal in P. endroedyi ) and by distinctly shorter setae d , which are far away from reaching the posterior margin of the body ( d reaching beyond posterior margin of the body in P. endroedyi ).