Acarina 17 (2): 109–169 © Acarina 2009 MITES OF THE FAMILY MYOBIIDAE (ACARI: PROSTIGMATA) PARASITIZING RODENTS OF THE FORMER USSR A.V. Bochkov1, 2 1Zoological Institute of the Russian Academy of Sciences, Universitetskaya Emb. 1, 199034 Saint Pe- tersburg, Russia; e-mail: [email protected] 2Museum of Zoology, University of Michigan, 1109 Geddes Ave., Ann Arbor, Michigan 48109, USA ABSTRACT: Records of myobiid mites parasitizing rodents of the former USSR are summarized. Totally, 46 myobiid species belonging to 4 genera were recorded in the fauna of the former USSR: Austromyobia (2 species), Cryptomyobia (10 species), Myobia (7 species), and Radfordia with the 3 subgenera, Radfordia s.str. (4 species), Graphiurobia (6 species), and Microtimyobia (17 species). Seventy one rodent species were recorded as hosts of myobiids. More than 60% of potential myobiid hosts occur- ring in the fauna of the former USSR were examined. Keys to all recorded genera, subgenera, and species (males, females, and tritonymphs of most subgenera) are provided and supplied by figures where it is necessary. The emended diagnoses of all recorded mite genera and subgenera are provided. One species, Radfordia (Graphiurobia) selevinia sp. nov. from Selevinia betpakdalensis (Gliridae) is described as a new for science. The host-parasite relationships of myobiids and rodents of the former USSR are briefly discussed. In the examined region, myobiids are absent on representatives of the suborders Castorimorpha and Hystricomorpha. Among Sciuromorpha, myobiids (subgenus Graphiurobia) are recorded only on representatives of the family Gliridae. The suborder Myomorpha harbors myobiids of the 3 genera: Cryptomyobia — parasites of Dipodidae, excluding Sicistinae); Austromyobia — parasites of Gerbillinae, Myobia and Radfordia s.str. — parasites of Murinae, Radfrodia (Microtimyobia) — parasites of Cricetidae. Among the superfamily Muroidea, myobiids are absent on representatives of the families Calomyscidae and Spalacidae. Finally, myobiids have, probably, been extinct on some cricetids having the subterranean mode of life, such as Ellobius spp. and Pro- metheomys schaposchnikovi. Their absence on species of the genus Lagurus (Cricetidae) is, probably, the result of the “missing of the boat”. KEY WORDS: Myobiidae, mites, parasites, rodents, fauna of the former USSR, systematics INTRODUCTION The family Myobiidae includes about 585 Mites of the subfamily Myobiinae parasitize species and subspecies belonging to 53 genera. rodents (Rodentia) being recorded on representa- All myobiids are permanent mono- or ologoxeno- tives of 12 from 33 recognized rodent families us ectoparasites associated with small marsupial (Carleton and Musser 2005). According to the or placental mammals of 11 orders (Bochkov system by Carleton and Musser (2005), the order 2008). The phylogenetic relationships of myobiids Rodentia is divided into the five suborders, Anom- with other members of the parvorder Eleutheren- aluromorpha, Hystricomorpha, Castoriomorpha, gona are not quite clear, although, most probably, Myomorpha, and Sciuromorpha. Myobiids are they belong to the early derivative Raphignathae known from representatives of all rodent subor- (Bochkov et al. 2008; Mironov and Bochkov ders. The fauna of the former USSR includes ro- 2009). dents of 10 families belonging to four suborders, According to the classification proposed by representatives of Anomalumorpha are absent. Bochkov (1997c), the family Myobiidae contains Earlir data about myobiids associated with ro- four subfamilies, the two of them, Archemyobii- dents of the fauna USSR were published by Dubi- nae and Xenomyobiinae are associated with mar- nin and Volgin (1955). Later on, several special supials and the two others, Myobiinae and Proto- papers concerning myobiids parasitizing various myobiinae, — with placental mammals. rodent families on territory of the former USSR Myobiids and their hosts demonstrate the high were published: parasites of Cricetidae (Bochkov level of the phylogenetic congruence (Bochkov 1995, 1999a; Bochkov and Mironov 1998), para- 2008). The myobiid subfamilies associated with sites of Gliridae (Bochkov 1994), parasites of jer- marsupials are much more archaic than mites par- boas and gerbils (Bochkov et al. 1990; Bochkov asitizing placental hosts. Based on the wide distri- 1997b), parasites of Muridae (Bochkov 1997b; bution of myobiid mites on both marsupial and Bochkov and Labrzycka 2003). In addition, a few placental hosts and the presence of the specific faunistic papers containing data about myobiids mite faunas on these hosts it is possible to hypoth- from rodents of the former USSR were published: esize that parasitism in myobiids originated not Ukraine (Donetsk Prov.) (Sklyar 1975), Crimea later than in the early Cenozoic, the time of the (Dubinina and Sosnina 1977); Kirghizia (Chirov probable divergence of marsupial and placental et al. 1997), Volzhsko-Kamsky Reservation (Du- mammals (Carroll 1993). binin 1953), parasites of Microtus miurus egorovi 109 A. V. Bochkov from Pleistocene of Yakutia (Dubinina and Boch- Mites collected from freshly killed or ethanol kov 1996). preserved hosts were cleaned, if necessary, in lac- In this paper, I summarize all records of myo- tophenol or lactic acid before mounting. Mites biid mites parasitizing rodents of the former USSR collected from dry skins were initially put in the based on published data, acarological collection of Nesbitt solution to mollify and clear them for the Zoological Institute of the Russian Academy 10–20 hours at the home temperature or for 4–5 of Sciences, Saint-Petersburg (ZISP), personally minutes in the hot solution. collected materials from freshly trapped hosts in In the descriptions, the idiosomal chaetotaxy expeditions and from dry and ethanol preserved follows Grandjean (1939) as interpreted by Boch- hosts housing in ZISP. Keys to all recorded gen- kov et al. (2008). The leg chaetotaxy follows era, subgenera, and species (males, females, and Grandjean (1944). All measurements are in mi- tritonymphs of most subgenera) are provided and crometres (μm). supplied with figures where it is necessary. The Host systematics follows the check list of myobiid tritonymphs are the most often numerous Carleton and Musser (2005). Authors and years of on rodents, therefore keys to this stage are very host species occurring in the fauna of the former important. The emended diagnoses of all recorded USSR are given in Table 2. mite genera and subgenera are provided. One new species, Radfordia (Graphiurobia) selevinia sp. SYSTEMATICS nov. from Selevinia betpakdalensis (Gliridae) is Family Myobiidae Megnin, 1878 described. The host-parasite associations of myo- Subfamily Myobiinae Megnin, 1878 biids and rodents of the former USSR are briefly discussed. Recorded myobiid species along with Type genus: Myobia van Heyden, 1826 the lists of their hosts and their distribution on ro- Adults. Coxae I with 4 setae (in Myobia dents of the former USSR are summarized in Ta- machadoi Fain, 1972, with 3 setae). Three apical bles 1 and 2, respectively. segments of legs I (tarsus, tibia, and genu) com- MATERIAL AND METHODS pletely fused; genua I each with large external The materials used in this paper were obtained clasping projection; tarsal claws absent. Legs I from two main sources: acarological and mammal significantly shorter than legs II–IV. collections housed in ZISP and from hosts cap- Female. Vulvar lobes distinctly developed, tured in nature. their apices bearing seta ps3, which claw-like in Some materials were kindly loaned to ZISP most genera. Setae h1 whip-like. by Drs. P.A. Chirov (Kirghizia), A. Fain (from Male. Genital shield bearing maximally 8 se- various regions), G.I. Gushcha and S.A. Zablu- tae, ps1–ps3, g1, g2, c1, d1, and d2. Other hyster- dovskaya (Ukraine), and F. Lukoschus (Europe). onotal setae c2, e1, e2, f1, and h1. In the field work, mites were collected from Immature instars. Idiosomal setae vi pres- hosts captured with snap traps (Gerro‘s traps) or ent. Inner side of tarsi I bearing large clasping trap cylinders. The trapped hosts were placed indi- projection; femora-genu I bearing thickened vidually in cotton fabric bags and delivered to the club-like seta on the inner side; this club-like seta lab. The hosts were determined by either mam- and clasping projection forming chela-like struc- mologists or by me; in the latter case my determi- ture. nations were checked later by experts from the This subfamily includes eight genera other Department of Theriology (ZISP). than the type genus: Anuncomyobia Fain, 1972, Mites were collected from host in the field or Austromyobia Lawrence, 1954, Cryptomyobia from specimens housed in museums (dry skins Radford, 1954, Gundimyobia Fain et Lukoschus, and alcohol preserved individuals) under the dis- 1976, Idiurobia Fain, 1973, Lavoimyobia Paran, section microscope by means of pincers for elec- 1966, Proradfordia Lukoschus, Dusbabek et tron microscopy or sharpened dissecting needles jameson, 1973, and Radfordia Ewing, 1938. and put in laboratory microtubes (up to 500 μL) with 70–96% ethanol. In many cases, when the Remark. The fauna of the former USSR in- immediate field collecting of mites was not possi- cludes four genera: Myobia, Austromyobia, Cryp- ble, the alcohol preserved host specimens were tomyobia, and Radfordia. wrapped into bandages by collectors to prevent Hosts. Species of this subfamily associated any technical contamination of parasites. exclusively with Rodentia (Bochkov 1997c).