Petalomium reductus Khaustov

Khaustov, Alexander A., 2015, Two new myrmecophilous species of the genus Petalomium (Acari: Pygmephoroidea: Neopygmephoridae), Zootaxa 3999 (4), pp. 549-559 : 554-556

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.

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 ).

Figures

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.

FIGURE 7. Petalomium reductus Khaustov sp. nov., female: A—leg III in dorsal view, B—leg IV in dorsal view.