UDC: 595.42(55) A NEW REPORT ON Arctoseius (Acari; Ascidae) FROM KHORASAN RAZAVI REGION, IRAN M. Mehranian Islamic Azad University, Neyshabour Branch, Iran Keywords: Arctoseius, mite, seta, dorsal shield ntroduction. The Arthropoda phylum, Chelicerata subphylum, Arachnida class, Acari subclass, is characterized by a large Idiversity of shapes, dimensions and structures. Mites (Acari or Acarina) are the most diverse and abundant of all arachnids, but because of their small size (usually less than a millimeter in length) we rarely see them. Mites are also among the oldest of all terrestrial animals, with fossils known from the early Devonian, nearly 400 million years ago (Norton et al., 1988). Three major lineages are currently recognized: Opilioacariformes, Acariformes and Parasitiformes (Krantz, 1986; Evans, 1992). Mites are truly ubiquitous. They have successfully colonized nearly every known terrestrial, marine, and fresh water habitat including polar and alpine extremes, tropical lowlands and desert barrens, surface and mineral soils to depths of 10 meters, cold and thermal surface springs and subterranean waters with temperatures as high as 500 C, all types of streams, ponds and lakes, and sea waters of continental shelves and deep sea trenches to depths of 5000 meters. Many mites have complex symbiotic associations with the larger organisms on which they live. Plants, including crops and the canopies of tropical rainforests, are inhabited by myriads of mite species feeding on mosses, ferns, leaves, stems, flowers, fruit, lichens, microbes, other arthropods and each other. Many mites found on agricultural crops are major economic pests (e.g. spider mites) or useful biocontrol agents (e.g. phytoseiid mites) of those pests (Sabelis et al. 1996). Mammals and birds are hosts to innumerable species of parasitic mites, as are many reptiles and some amphibians (Ambros 1996). Insects, especially those that build nests, live in semipermanent habitats like decaying wood, or use more ephemeral habitats like bracket fungi and dung, are hosts to a cornucopia of mite commensals, parasites and mutualists (Binns 1973). None of these mites exceed a centimeter in length, and the vast majority grows to less than a millimeter, yet they often have a major impact on their hosts. Ascids are mites belonging to the suborder Mesostigmata of the Parasitiformes order. Parasitiformes consists of three orders: Ixodida, Holothyrida, and Mesostigmata (Lindquist et al., 1965). The Mesostigmata contains in excess of 65 families and 10,000 described species. Mesostigmata may be differentiated from other mites by the presence of a bifurcate structure, the tritosternum, between the first pair of legs. Mesostigmatans are also characterized by having the openings to their respiratory tubes, the stigmata, on the sides of the body between the 2nd and 4th pairs of legs (Halliday et al., 1998). Material and Methods. During field research in 2008-2009, samples were collected from various microhabitats such as leaf litter, rotten wood and mosses. Mites were extracted from the samples in Berlese-Tullgren funnel and preserved in 80% alcohol. Specimens were cleared in lactophenol solution and mounted in Hoyer's medium on microscope slides (Evans, 1992). Measurements are given in parentheses (in micrometers) and were made from slide-mounted specimens using a stage-calibrated ocular micrometer. Slid-mounted specimens are deposited in mite collection of Islamic Azad University branch scientific and research centers, Iran. Results and Discussion. Arctoseius cetratus (Sellnick) diagnosis is as follows: dorsal shield of adult mite is with 31 pairs of seta; Z1 and Z2 never arrive to the next pair of setae: Z1,Z2,Z3,Z4=16-22 μm long and only Z5 is markedly longer, Z5=35-45 μm (Figure 2a); Tectum with 2 bifid prongs; the branches are equal in length (Figure 2b); Idiosoma of female equals to 310- 360μm long and male – 270-280μm long; vertex of dorsal shield not strongly arched downward, setae j1 visible from aboveon podonotal shield; anterior extremities of peritermes not recurved; dorsal shield with mid lateral incisions (Karg, 1993). Anal shield is with 3 pairs of setae (Figures 2c and 3); sternal shield with 3 pairs of setae and is weakly sclerotized; genital shield is truncate. Tibia 2 without al2; Tibia 1 with 5 dorsal setae; Tibia 3, 4 with 7 setae or more; tarsi II-IV with neither of dorso – lateral subapical setae slender and elongate; palp tarsus without macrosetae; movable digit of chelicera bidentate; spermatodactyl fingerforming (Figure 1). These species were collected from different areas of Khorasan Razavi province, including Neyshabur, Mashad, Esfarayen and Quchan, in Iran. These mites are predators and have free living and play a good role in general equilibrium position of many of other arthropoda that are able to act as pest, therefore these animals have a potential of biological control in agricultural or natural ecosystem. 64 Taxonomic Position. Cohort: Gamasina, Subcohort: Figure 1. Chelicera, Spermatodactyl Dermanyssiae, Superfamily: Ascoidea, Family: Ascidae Voigts & Oudemans, Subfamily: Arctoseiinae, Arctoseius Thor Diagnostic Characters. The diagnostic characters are: arctoseiinae with entire or shallowly incised dorsal shield, vertex not strongly arched downward, j1 visible from above (Lindquist, 1961). Anterior extremities of peritremes are not recurved; Tarsi II-IV are with neither of dorso-lateral subapical setae slender and elongate. Palp tarsus is without macroseta. Keys to Genera of Arctoseiinae 1. Leg chaetotaxy reduced, maximum setation: genu II = 10, genu IV = 7, tibia III = 7, tibia IV = 7; opisthonotal region of dorsal shield usually with 4 pairs of lateral setae (S1 present, S2 usually absent); deutosternal denticular rows moderately wide, multidenticulate..... 2 - Leg chaetotaxy without above reductions, minimum setation: genu II = 11, genu IV = 9, tibia III = 8, tibia IV = 10; opisthonotal region of dorsal shield usually with 5 pairs of lateral setae (S2 present, S1 rarely absent); deutosternal denticular rows narrow, each with few (usually 2-6) denticles................ 5 Figure 2. A) Dorsal, B) Tectum, C) Ventral 2. Tarsi II-IV each with dorso-proximal setae ad2, pd2 elongate, curved; genu III usually with 8 setae; female with ventrianal shield bearing 1-6 pairs of ventral setae in addition to circumanal setae................... 3 - Tarsi II-IV with dorso-proximal setae not elongate or curved; genu III with 7 setae (pv1 absent); female with anal shield bearing only circum-anal setae (rarely with ventral setae JV3 on shield)................. 4 3 . Tarsus I without claws; dorsal shield setae j1 & z1 smooth, short and blunt or barbed and variable in length; other dorsal shield setae simple (J5 sometimes barbed), none paddle-shaped ................... Xenoseius - Tarsus I with claws; dorsal shield setae j1 and z1 smooth, pointed (j1 rarely paddle-shaped), variable in length; some dorsal shield setae (always s4 and Z5) paddle-shaped................. Zerconopsis 4. Vertex of dorsal shield strongly arched downward, setae j1 concealed from above; peritremes sharply recurved distally; dorsal shield without midlateral incisions; tarsi II-IV with 1 (al1) or 2 (al1, Figure 3. Arctoseius Cetratus: Ventral View pl1) dorso-lateral subapical setae very slender and elongate; palp tarsus with macroseta ................... Iphidozercon - Vertex of dorsal shield not strongly arched downward, setae j1 visible from above; anterior extremities of peritremes not recurved; dorsal shield with or without midlateral incisions; tarsi II-IV with neither of dorso-lateral subapical setae slender and elongate; palp tarsus without macroseta....................Arctoseius 5. Dorsal shield lacking setae z1; epistome convex and smooth or slightly denticulate; genu I with 12 setae (av2 absent), tibia II with 9 setae (ad2 absent) .......................... 6 - Setae z1 present; tectum bi- or triramous; genu I with 13 setae, tibia II with 10 setae......................... 7 6. Dorsal shield with midlateral incisions; all r-R marginal setae on soft cuticle flanking dorsal shield; female with: first pair of sternal setae on sternal shield, genital setae and pores on soft cuticle 65 flanking epigynial shield, anal shield bearing only circum-anal setae ...................................................... Arctopsis - Dorsal shield lacking midlateral incisions; r-R marginal setae on edges of dorsal shield; female with: first pair of sternal setae on jugular plates separated from sternal shield or on margin of shield, genital setae and pores on epigynial shield, ventri-anal shield incorporating metapodal plates and bearing 4-5 pairs of setae in addition to circum-anal setae ........................................................................... Neojordensia 7. Dorsal shield lacking setae z3, J2, S1; R3, R4 on dorsal shield, others (r6, R2, R5) absent; genu and tibia I each with 12 setae (av2 absent); genu III with 10 setae, tibia III with 9 setae (pl2 present on both); genu IV with 10 setae (pv1 present) .......................................................................... Arctoseiodes - Dorsal shield holotrichous, with z3, J2, S1; 10-11 pairs of marginal r-R setae on soft cuticle laterally, none on dorsal shield; genu and tibia I each with 13 setae (av2 present); genu III with 8-9 setae, tibia III with 8 setae (pl2 absent on both); genu IV with 8-9 setae (pv1 absent) ......... Leioseius REFERENCES Ambros, M. (1996). Mites (Acari: Mesostigmata) from Small Mammals (Insectivora