Imparipes Berlese, 1903

Jagersbacher-Baumann, Julia & Ebermann, Ernst, 2016, Support for the underrepresented sex: new descriptions of scutacarid males (Acari, Heterostigmatina), Zootaxa 4179 (3), pp. 371-409 : 378-379

Genus Imparipes Berlese, 1903

Type species Imparipes histricinus Berlese, 1903 , by original designation

Imparipes (Sporichneuthes) dispar Rack, 1964 ( Figs. 1 , 3 , 5–7)

MALE. Idiosoma length 130–190, n = 10.

Gnathosoma ( Fig. 1 b) extended, tube-shaped. One pair of finger-shaped solenidia, two pairs of dorsal setae ch 1 and ch 2, thin, smooth, short, one ventral pair of setae su long, barbed.

Dorsum (Fig. 5a). Idiosoma with four sclerotized, smooth plates. Most posterior plate forms dorsal cover for genital capsule. Length of dorsal setae: v about 8, sc 1 14, sc 2 65, c 1 50, c 2 73, d 93, e 26, f 54, h 1 8. Setae v not barbed, sc 1, sc 2, c 1, c 2, d, e, f thick, barbed, all setae pointed. Setae h 1 and h 2 smooth, h 1 blunt, h 2 minute. Distance between dorsal setae: v–v about 12, sc1–sc1 13, sc 2 –sc 2 19, c 1 –c 1 34, c 2 –c 2 76, d–d 57, e–e 42, f–f 26, h 1 –h 1 23, h 2 –h 2 29.

Genital apparatus ( Figs. 3 b, 5a, 6). Segments H and PS fused, form genital capsule. Length of genital plate (tergite H) about 38. Posterior edge of plate narrowed, short genital plate (ratio length: width of genital plate = 1: 0.62). Soft skinned area posterior of h 1 with roundish, sucker-like structures or cavities (difficult to discern in microscopic slides, but clearly recognisable in REM; Fig. 6 ). Aedeagus transversely striated, continues internally as ductus ejaculatorius leading into a seminal vesicle.

Venter (Fig. 5b). Sternal plates very finely dotted. Ap1, ap2, sejugal ap clearly sclerotized; prosternal ap almost continuous from ap1 to sejugal ap, strongly sclerotized; ap3, ap4 weakly sclerotized, sclerotization of ap3 stronger around 3 c, ap4 incomplete; ap5 clearly sclerotized; poststernal ap incomplete, between ap4 and ap5 strongly sclerotized. Length of ventral setae: 1 a about 30, 1 b 31, 2 a 37, 2 b 34, 3 a 26, 3 b 23, 3 c 27, 4 a 18, 4 b 18, 4 c 27, ps 1 6, ps 2 7. Setae 1 a, 1 b, 2 a, 2 b thick, long, barbed; setae 3 a, 3 b, 3 c, 4 a, 4 b, 4 c only sparsely barbed; setae ps smooth; all setae pointed. Distance between ventral setae: 1 a –1 a about 13, 1 b –1 b 45, 2 a –2 a 23, 2 b –2 b 38, 3 a –3 a 27, 3 b –3 b 44, 3 c –3 c 60, 4 a –4 a 21, 4 b –4 b 6, 4 c –4 c 57, ps 1 –ps 1 15, ps 2 –ps 2 19.

Leg I ( Fig. 7 a). Setal formula: Tr1–Fe3–Ge4–Ti6(2)–Ta13(2). Ta with one small padded claw. Sol ω2 thick and finger-shaped, ω1 thin, ϕ2 thin, baculiform, ϕ1 club-shaped. Length of solenidia: ω1 about 13, ω2 7, ϕ1 6, ϕ2 6. Eupathidia tc’ and tc’’ situated on a process. Eupathidia tc’, tc’’, and setae u’, s, v’Ti and v’’Fe smooth, all other setae barbed, some only sparsely; all setae pointed.

Leg II ( Fig. 7 b). Setal formula: Tr1–Fe3–Ge3–Ti4(1)–Ta7(1). Ta with two small claws and empodium. Sol ω thick, finger-shaped, ϕ club-shaped, ω 12, ϕ 5. Seta dTi smooth, all other setae barbed, some only sparsely; all setae pointed.

Leg III ( Fig. 7 c). Setal formula: Tr1–Fe2–Ge2–Ti4(1)–Ta7. Ta with two small claws and empodium, Sol ϕ 5, finger-shaped. Setae u’ and l’Fe smooth, all other setae barbed, some only sparsely; all setae pointed.

Leg IV ( Figs. 6 , 7 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 tc’ about 116, tc’’ 92. v’’Ti spine-like, smooth, dTi, u, pl’’ and pv’’ short, thin, smooth, all other setae barbed, pointed; ϕ 12, thin.

Differential diagnosis. The male of I. dispar can be differentiated from all other known males by the presence of long and barbed ventral setae 1 a, 1 b, 2 a and 2 b.

Material examined. 50 males from laboratory cultures based on females from a compost heap; AUSTRIA: Haselsdorf, 46°59’30’’N, 15°20’39’’E, 1992, leg. Ebermann.

Deposition of material. 2 males: Natural History Museum Vienna, Austria ( NHMW 27.639 ) ; 46 males: Institute of Zoology , University of Graz, Austria ; 2 males: Museum of Natural History of the City of Geneva, Switzerland .

FiGURE 5. Imparipes dispar male: a. dorsal view, b. ventral view.

Figures

FIGURE 1. Dorsal view of the male gnathosoma: a. Heterodispus foveatus, b. Imparipes dispar, c. Lamnacarus ornatus, d. Scutacarus acarorum, e. S. deserticolus, f. S. ellipticus, g. S. longipes, h. S. longitarsus, i. S. tackei, j. S. tyrrhenicus. Abbreviations: ass = accessory setigenous structures.

FIGURE 3. Dorsal view of the genital plates of: a. Heterodispus foveatus, b. Imparipes dispar, c. Lamnacarus ornatus, d. Scutacarus acarorum, e. S. deserticolus, f. S. ellipticus, g. S. longipes, h. S. longitarsus, i. S. tackei, j. S. tyrrhenicus large male (idiosoma length 200 µm), k. S. tyrrhenicus small male (idiosoma length 140 µm).

FIGURE 6. Scanning electron micrographs of the genital apparatus and legs IV of an Imparipes dispar male covered with fungal spores: a. Posterior view of the genital apparatus and legs IV, b. detail of the two adhesive pads on the tarsus of leg IV, c. dorsal view of the tarsus and partly tibia of leg IV. Abbreviations: adp = adhesive pads, gp = genital plate, sp = spore (s).

FIGURE 7. Imparipes dispar male: a. leg I, b. leg II, c. leg III, d. leg IV.