Helvetacarus genavensis, Mahunka, S., 1993

Mahunka, S., 1993, Oribatids from Switzerland I. (Acari: Oribatida). (Acarologica Genavensia LXXXI), Archives des Sciences, Geneve 46, pp. 51-56 : 52-54

Helvetacarus genavensis sp. n.

Measurements. - Length of aspis: 244-261 µm, length of notogaster: 489- 514 µm, height of notogaster: 298-327 µm.

Aspis: Median crista low, lateral carina very short, only its short part observable in front of the bothridium (Fig. 3). Lateral rim not reaching to the rostrum. Surface ornamented by weak foveolae medially and anteriorly, lateral part smooth. Basal part of aspis bordered anteriorly by a transversal lath connecting the insertion-points of the lamellar and interlamellar setae. This transversal lath is connected with the lateral longitudinal wrinkles, and they compose a characteristic quadrangular formation (Fig. 7). Rostral setae slightly dilated basally, lamellar and interlamellar setae straight, strongly ciliate, interlamellar ones scarcely longer than the lamellar ones. Sensillus long, bended inwards, without any thickening, its distal half with serrated velum. Exobothridial setae short, but clearly visible.

Notogaster: Surface ornamented by weak foveolae. Eighteen pairs of mostly simple, bacilliform (Fig. 1) notogastral setae present (Fig. 2), all setae nearly straight, never widened to their distal part. Their distal half spiculate (Fig. 4). Two pairs of lyrifissures and two pairs of alveoli of the f1 and f2 setae also observable.

Anogenital region (Fig. 6): Nine pairs of genital setae present, all arising on the inner margin of the genito-aggenital plate. Among the setae of the anogenital plates four pairs located in a longitudinal row along the inner margin. All four nearly equal in length, no essential difference among them. Their length much shorter than the distance between their insertion-points (Fig. 5). Setae ad3 much shorter than the others.

Legs: Legs with normal chaetotaxy, femur of leg I with 4 setae, seta d located near to the anterior margin of the Joint, simply curved anteriorly. Setae d of tibia IV minute, coupled with the solenidium. The setal formulae are:

I: 1-4-2+2-5+ 1-16+3-1 (Fig. 8)

II: 1-3-2+1-1-3+1-12+2-1

IV: 2-1-1-1+1-10-1 (Fig. 9)

Material examined: Holotype: SUISSE (Glaris): Kloental s/Riedern, 700 m , 30.VIII. 1980, vieille souche, leg. C. Besuchet ; 2 paratypes from the same sample . Holotype and 1 paratype deposited in the Muséum d'Histoire naturelle, Genève and 1 paratype (1501-PO-92) in the Hungarian Natural History Museum, Budapest (with identification number of the specimens in the Collection of Arachnida).

Remarks: As I mentioned above, I want to place in this genus two other species, namely H. mirabilis (Mahunka, 1979) and H. inconditus (Mahunka, 1991). The new species is distinguished from both other species by the simple, bacilliform notogastral setae. The three species of this genus might be identified by the following key:

1(2) Notogastral setae simple, on their distal end not thicker than basally................................................. H. genavensis n. sp.

2(1) Notogastral setae dilated, their distal end much thicker than their basal part, or some of them fusiform

3(4) Anoadanal setae located on the inner margin of the anal plates, not longer than the distance between them (Fig. 11). Setae c1 and c2 spindle-shaped (Fig. 12)................................................... H. mirabilis (Mahunka, 1979)

4(3) Anoadanal setae located in the inner margin of the plates, much (three times) longer than the distance between them. Setae c1 and c2 fusiform (Fig. 10).................................................. H. inconditus (Mahunka, 1991)