Radfordia (Microtimyobia), Fain and Lukoschus, 1976

Bochkov, Andre V., 2011, Mites of the subgenus Microtimyobia (Acariformes: Myobiidae: Radfordia) and their host-parasite relationships with cricetid rodents (Cricetidae) 2954, Zootaxa 2954 (1), pp. 1-86 : 6-7

Subgenus Microtimyobia Fain and Lukoschus, 1976

Radfordia (Microtimyobia) Fain and Lukoschus, 1976: 178 ; 1977: 49; Bochkov 1995: 481; 2009b: 146; Bochkov & Mironov 1998: 311

Type-species: Dermaleichus lemninus Koch, 1841 by original designation

Diagnosis. Subcapitulum without ventral projections (in R. zibethicalis , with pair of rounded lobes). Subcapitular setae m membranous lanceolate or fan-like with several teeth, more rarely filiform. Setae 4a only slightly longer than 1a and in most species slightly thickened. Setation of legs II–IV: coxae 3-1-1, trochanters 3-3-3, femora 5-3-3, genua 7+ 1 solenidion-6-5, tibiae 6-6-6, tarsi 7+1 solenidion-6-6. Setae of coxae I, 1b, 1c, and 1d thickened. Dorsal seta d of trochanters III-IV whip-like (in males of R. dinaromys sp. nov., dorsal seta of trochanter III shorter than segment). Apical segment of legs I without hook.

FEMALE. Subcapitular setae m membranous lanceolate or fan-like with several teeth (in R. abramovi , filiform). Vulvar lobes distinctly developed. Vulvar region covered by tubercles or smooth. Full set of idiosomal setae present. Setae vi lanceolate, wider or subequal in width to setae e2.

MALE. Subcapitular setae m membranous lanceolate or fan-like with several teeth, more rarely filiform. Genital shield replaced by elongated genital cone bearing 2 pairs of pseudoanal setae; setae ps1 finger-like. Setae d1 present, situated immediately behind genital cone, setae c1, d2, f2, and h2 absent. Seta si close located to se, distance si-se distinctly shorter than si - genital cone. Setae 3a short (in R. abramovi whip-like). Cuticular ornamentation near bases of setae h1 well pronounced, or almost absent.

TRITONYMPH. Idiosoma with 16 pairs of setae, including pseudoanal setae: vi, ve, si, se, c1, c2, d1, d2, e1, e2, f1, f2, h1, h2, ps1, and ps2. Coxal fields I–IV with 3-2-1-1 setae respectively; setae 1b and 1c scale-like. Legs IV with 4 articulated segments, femur and genu completely fused. Tarsi II–III with 1 claw, tarsi IV without claw, with 4 setae, in some species with 3-1 setae or without setae. In female TN, lengths of setae 3a and 4a highly variable; in male TN, these setae always short, shorter than 2a.

This subgenus includes 20 species other than the type species: R. abramovi Bochkov and Mironov, 1998 , R. alticolae Bochkov, 1995 , R. arborimus Fain and Whitaker, 1975 , R. arctica Fain and Lukoschus, 1977 , R. arvicolae Fain and Lukoschus, 1977 , R. clethrionomys Fain and Lukoschus, 1977 , R. cricetuliphila Bochkov, 1999 , R. cricetulus Fain, 1973 , R. dinaromys sp. nov., R. eothenomys Fain and Lukoschus, 1976 , R. golenishchevi sp. nov., R. hylandi Fain and Lukoschus, 1977 , R. ladakensis Fain and Lukoschus, 1976 , R. lemmus Fain and Lukoschus, 1977 , R. myopusi Bochkov and Mironov, 1998 , R. pitymys sp. nov., R. rufocani Bochkov, 1995 , R. synaptomysi Bochkov and Mironov, 1998 , R. triton Fain and Lukoschus, 1977 , R. zibethicalis ( Radford, 1936) .

Remarks. This subgenus differs from the closely related subgenus Graphiurobia Fain by the following features. In both sexes of the subgenus Microtimyobia , subcapitular setae m are membranous (in females and many males), setae 1b, 1c, and 1d are distinctly thickened; in females, the vulvar region is sometimes ornamented; in males, setae ps3 are absent. In both sexes of Graphiurobia , subcapitular setae m are filiform, setae 1b, 1c, and 1d are not thickened; in females, the vulvar region is never ornamented. In males, setae ps3 are absent. In male TN associated with voles, the opisthosoma bears a pair of distinct narrow lateral projections ( Fig. 8 ).

External morphology of immature instars was described with the example of Radfordia triton Fain and Lukoschus, 1977 ( Figs. 50–54 ). The pattern of appearance of morphological structures in ontogeny corresponds to that observed by Uchikawa et al. (1997) in Radfordia lemnina from Microtus montebelli .

This subgenus includes six species groups, i.e. lemnina (7 species), hylandi (7 species), zibethicalis (1 species), dinaromys (1 species), arborimus (1 species), and triton (4 species).

Hosts. Seventeen species of this genus belonging to five species groups are associated with voles of the subfamily Arvicolinae , four species comprising the triton group parasitize hamsters of the subfamily Cricetinae .

Figures

FIGURE 8. Radfordia (M.) lemnina (Koch, 1841), tritonymph from Microtus arvalis. A, female TN in dorsal view; B, same in ventral view; C, leg IV of female TN in dorsal view; D, male TN in dorsal view; E, same in ventral view; F, leg IV of male TN in dorsal view. Scale bars: A, B, D, E = 100 µm; C, F = 50 µm.

FIGURE 50. Radfordia (M.) triton Fain and Lukoschus, 1977, protonymph. A, idiosoma in dorsal view; B, same in ventral view; C, leg II in ventral view; D, leg III in ventral view. Scale bars: A, B = 100 µm; C, D = 50 µm.

FIGURE 51. Radfordia (M.) triton Fain and Lukoschus, 1977, deutonymph. A, idiosoma in dorsal view; B, same in ventral view; C, leg II in ventral view; D, leg III in ventral view; E, leg IV in ventral view. Scale bars: A, B = 100 µm; C–E = 50 µm.

FIGURE 52. Radfordia (M.) triton Fain and Lukoschus, 1977, female tritonymph. A, idiosoma in dorsal view; B, same in ventral view; C, tarsus IV in ventral view. Male tritonymph. D, idiosoma in dorsal view; E, same in ventral view; F, tarsus IV in ventral view. Scale bars: A, B, D, E = 100 µm; C, F = 50 µm.

FIGURE 53. Radfordia (M.) triton Fain and Lukoschus, 1977, leg I of female tritonymph. A, dorsal view; B, ventral view.

FIGURE 54. Radfordia (M.) triton Fain and Lukoschus, 1977, legs II–IV of female tritonymph in ventral view. A, leg II; B, leg III; C, leg IV.