Scutacarus longitarsus Berlese 1905

Scutacarus longitarsus (Berlese, 1905)

(Figs. 1, 3, 18, 19)

MALE. Idiosoma length 110–170, n = 8.

Gnathosoma (Fig. 1 h) extended, tube-shaped. One pair of finger-shaped solenidia, two pairs of dorsal setae ch 1 and ch 2 and one ventral pair of ventral setae su, thin, smooth, ch 1 slightly shorter than ch 2 and su. One pair of short tube-like accessory setigenous structures distally.

Dorsum (Fig. 18 a). Idiosoma with four sclerotized, finely dotted plates. Most posterior plate forms dorsal cover for genital capsule. Length of dorsal setae: v about 7, sc 1 6, sc 2 43, c 1 31, c 2 39, d 43, e 55, f 74, h 1 7. Setae v, sc 1 smooth, pointed. sc 2, c 1, c 2, d, e, f sparsely barbed, in e and f barbs horsetail-like, blunt-ended. h 1 and h 2 spinelike, h 2 small. Distance between dorsal setae: v–v about 7, sc 1 –sc 1 21, sc 2 –sc 2 23, c 1 –c 1 23, c 2 –c 2 70, d–d 39, e–e 47, f–f 18, h 1 –h 1 24, h 2 –h 2 26.

Genital apparatus (Figs. 3 h, 18a). Segments H and PS fused, form genital capsule. Length of genital plate (tergite H) about 65. Posterior edge of plate narrowed, long genital plate (ratio length: width of genital plate = 1: 0.38). Area posterior of h 1 soft-skinned, no sucker-like structures or cavities recognisable in microscopic slides. Aedeagus like in I. dispar.

Venter (Fig. 18 b). Sternal plates finely dotted. Ap1 weakly sclerotized, prosternal ap continuous from ap1 to sejugal ap, strongly sclerotized; ap2, complete, strongly sclerotized; sejugal ap, ap3, ap4 and ap5 complete, weakly sclerotized; poststernal ap between ap3 and ap5 complete, weakly sclerotized. Length of ventral setae: 1 a about 12, 1 b 11, 2 a 11, 2 b 13, 3 a 13, 3 b 11, 3 c 11, 4 a 11, 4 b 11, 4 c 11, ps 1 1, ps 2 5. All setae smooth, short, pointed. Distance between ventral setae: 1 a –1 a about 12, 1 b –1 b 34, 2 a –2 a 18, 2 b –2 b 36, 3 a –3 a 22, 3 b –3 b 35, 3 c –3 c 56, 4 a –4 a 21, 4 b –4 b 4, 4 c –4 c 48, ps 1 –ps 1 15, ps 2 –ps 2 17.

Leg I (Fig. 19 a). Setal formula: Tr1–Fe3–Ge4–Ti6(2)–Ta13(2). Ta with one small, padded claw. Sol ω1 thick, finger-shaped, sol ω2 thin, sol ϕ1 slightly club-shaped, sol ϕ2 thin. Length of solenidia: ω1 about 29, ω2 19, ϕ1 6, ϕ2 13. Setae pl’, v’Ti, v’’Ti, l’Ti, k, dTi, l’Ge, v’Ge and l’Fe sparsely barbed, all other setae smooth. Eupathidion tc’ blunt, all other setae pointed.

Leg II (Fig. 19 b). Setal formula: Tr1–Fe3–Ge3–Ti4(1)–Ta7(1). Ta with two small claws and empodium. Sol ω thick, sol ω and ϕ finger-shaped, sol ω 18, sol ϕ 7. Setae v’Ti, v’’Ti, dTi, l’Ti, v’Ge, l’Ge and dFe sparsely barbed, all other setae smooth; all setae pointed.

LegIII (Fig. 19 c). Setal formula: Tr1–Fe2–Ge2–Ti4(1)–Ta7. Ta with two small claws and empodium. Sol ϕ 6, finger-shaped. Setae v’Ti, v’’Ti and l’Ti sparsely barbed, all other setae smooth; all setae pointed.

LegIV (Fig. 19 d, Table 1). Setal formula: Tr1–Fe2–Ge1–Ti4(1)–Ta6. Distal Ta with two adhesive pads of differing size. Tarsal setae tc’, tc’’ are longest, length about tc’ 50, tc’’ 30. Seta dTi short, cone-like, smooth; v’Ge and tc’ slightly barbed, all other setae smooth, u minute. Sol ϕ 8, finger-shaped.

Differential diagnosis. Males of S. longitarsus can be differentiated from Archidispus, Heterodispus and Imparipes by the presence of accessory setigenous structures on the gnathosoma. Amongst the remaining males, S. longitarsus is most similar to S. longipes. The two species can be differentiated by S. longipes being shorter than S. longitarsus (idiosomal length about 125µm in S. longipes versus 154µm in S. longitarsus), and by the shape of sol ϕ1 on leg I which is considerably club-shaped in S. longipes and finger-shaped in S. longitarsus.

Material examined. 8 males from laboratory cultures based on females from soil near a pond; AUSTRIA: Unterpremstätten, 46°58'01.8"N, 15°23'32.1"E, 1986, leg. Ebermann; from manure; AUSTRIA: Muttendorf, 46°56'06.1"N, 15°21'41.4"E, 1987, leg. Ebermann.

Deposition of material. 2 males: Natural History Museum Vienna, Austria (NHMW 27.645); 4 males: Institute of Zoology, University of Graz, Austria; 2 males: Museum of Natural History of the City of Geneva, Switzerland.