Mites of the family Scutacaridae (Acari: Pygmephoroidea) associated with Formica fusca L. (Hymenoptera: Formicidae) from Western Siberia, Russia

Six species of scutacarid mites (Acari: Pygmephoroidea: Scutacaridae) are newly recorded phoretic on ants Formica fusca Linnaeus, 1758 (Hymenoptera: Formicidae) in Tyumen Province,Western Siberia, Russia. One of these species, Scutacarus karafiati n. sp. is described as new for science. Scutacarus pilatus Khaustov, 2008, S. rotundus (Berlese, 1903) and S. atypicus (Karafiat, 1959) are recorded for the first time in Russia. Scutacarus rotundus is redescribed based on material fromWestern Siberia.


INTRODUCTION
The cosmopolitan family Scutacaridae is the largest in the superfamily Pygmephoroidea and includes 24 genera and more than 800 species (Zhang et al. 2011). Probably all scutacarid mites are fungivorous (Khaustov 2008). Many scutacarid mites are phoretic on various ants (Ebermann and Moser 2008;Khaustov 2008;Ebermann et al. 2013), but scutacarid mites associated with particular species of ants are poorly studied. There is only one comprehensive study of scutacarid mites associated with the red imported fire ant, Solenopsis invicta Buren, 1972 (Ebermann and Moser 2008). Formica fusca Linnaeus, 1758 is a common Palaearctic ant species. Previously three species of scutacarid mites, Scutacarus rotundus (Berlese, 1903), S. silvestri (Berlese, 1903) and S. stammeri Karafiat, 1959 were recorded as associates of this ant (Berlese 1903;Karafiat 1959). The aim of this paper is to describe a new species and further provide five new records of scutacarid mites associated with Formica fusca from Western Siberia.

MATERIALS AND METHODS
Ants were collected in vials with 96 % alcohol and the sediments from the vials were inspected for phoretic mites. All collected mites were mounted in Hoyer's medium. The terminology of idiosoma and legs follows that of Lindquist (1986); the nomenclature of subcapitular setae and the designation of cheliceral setae follow that of Grandjean (1944Grandjean ( , 1947, respectively. The system of Pygmephoroidea follows that of Khaustov (2004Khaustov ( , 2008. All measurements are given in micrometers (µm) for the holotype and paratypes (in parentheses). For leg chaetotaxy the number of solenidia is given in parentheses. Scanning electron micrograph was made with the aid of JEOL -JSM-6510LV SEM microscope. The
Gnathosoma -Gnathosomal capsule short, oval, with well developed dorsal median apodeme, dorsally with two pairs of weakly barbed and pointed setae (cha, chb) and one pair of postpalpal setae (pp), situated anterolaterally to bases of setae cha. Palps dorsolaterally with subequal setae dFe and dGe. Ventral surface of gnathosoma not visible.
Idiosomal dorsum ( Figure 1A) -Prodorsum completely covered by tergite C, with two pairs of smooth needle-like setae v 2 and sc 2 , one pair of barbed capitate trichobothria, and one pair of oval stigmata. All dorsal shields with numerous small dimples. Cupules ia on tergite D and ih on tergite H large, round. Setae c 1 , c 2 , d and f thick, blunt-ended and distinctly barbed; setae e and h 2 pointed, curved medially and sparsely barbed; setae h 1 needle-like, smooth. Posterior margin of tergite EF undulate. Idiosomal venter ( Figure 1B) -All ventral plates with numerous small dimples. Apodemes 1 (ap1) well-developed and joined with prosternal apodeme (appr), apodemes 2 (ap2) w-like, joined with appr; sejugal apodeme (apsej) well developed and joined with appr. Secondary transverse apodeme well developed.
Male and larva unknown.
Etymology -The new species is named after Helmut Karafiat, a German acarologist, for his contribution to the study of European scutacarid mites.
Differential diagnosis -The new species is most similar to S. rotundus (Berlese, 1903) by thick and distinctly barbed setae c 1 , c 2 , d, f, curved and pointed e and h 2 , and very short h 1 . It differs from S. rotundus by setae f less than 1.5 times longer than d (f about two times longer than d in S. rotundus), setae h 1 needle-like and smooth (sparsely barbed and characteristically curved medially in S. rotundus), setae tc" of tibiotarsus IV shorter than pv' (tc" much longer than pv' in S. rotundus), setae 4c distinctly thickened, heavily barbed and not reaching beyond posterior margin of poststernal plate (setae 4c not thickened, sparsely barbed and reaching far beyond posterior margin of poststernal plate in S. rotundus), solenidia ω 2 and ϕ 2 subequal (solenidion ω 2 longer than ϕ 2 in S. rotundus).
Male and larva unknown. Remarks -This species was originally described from Italy (Berlese 1903) from ants Formica fusca. It was also recorded from Germany from Formica fusca and Lasius niger (Linnaeus, 1758) (Karafiat 1959); Austria from Formica rufa L., 1761 (Mahunka 1970); Hungary (Mahunka and Zaki 1984) and Ukraine (Sevastianov 1978). This is a new record for the fauna of Russia. Paoli (1911) studied specimens of S. rotundus in Berlese collection and provided redescription and illustrations of this species. Mahunka (1980) studied the type material of pygmephoroid mites in the Berlese collection and found out that the slide with a type specimen of S. rotundus was in a very bad condition. The other slide belonging to the type series of S. rotundus contained specimens of S. silvestri Berlese, 1903 andS. stammeri Karafiat, 1959. Khaustov A.A. FIGURE 6: Scanning electron micrograph of Scutacarus rotundus (Berlese, 1903), female: dorsum. Mahunka (1980) supposed that S. stammeri is a potential synonym of S. rotundus. Specimens from Western Siberia identified by me as S. rotundus completely fit to illustrations and description of S. rotundus provided by Paoli (1911) and clearly differ from S. stammeri. (Karafiat, 1959) Imparipes (Telodispus) atypicus Karafiat, 1959, p. 678, Fig. 23. Scutacarus atypicus: Ebermann 1980 This species was described from Germany from ant Formica rufa L., 1761 (Karafiat 1959). Ebermann (1980) recorded it from Austria from the nest of ant Myrmica ruginodis Nylander, 1846, redescribed it and transferred from the genus Imparipes to Scutacarus. Khaustov (2008) reported it from Western Ukraine from forest litter. This is a new record for the fauna of Russia.