Unicobelba ypsilonsignata, Mahunka, S., 1999

Mahunka, S., 1999, Oribatid mites from Switzerland, IV (Acari: Oribatida: Suctobelbidae), Acta Zoologica Academiae Scientiarum Hungaricae 45, pp. 375-381 : 378-380

Unicobelba ypsilonsignata sp. n.

(Figs 5-8)

Material examined - Holotype: "TI-5: Tessin: Monadello - Moneto , im faulenden Laub, Massif de refuge, 850 m; 23.IV.1992; leg. C. Besuchet." Five paratypes from the same sample , holotype and 3 paratypes in MHNG, 2 paratypes (1641-PO-99) deposited in the Hungarian Natural History Museum ( HNHM), Budapest, with identification number of the specimens in the Collection of Arachnida .

Measurements - Length of body: 256-278 µm, maximum width of body: 134-143 µm.

Prodorsum: Rostrum rounded, in dorsal view one pair of small lateral teeth visible. Nearly whole surface of prodorsum granulate, larger tubercles or pustules absent. Rostral setae bent inwards, not geniculate, basally well ciliate. Prodorsal margin serrate, among the small teeth no signi-

Figs 5-8. Unicobelba ypsilonsignata gen. n. et sp. n. 5 = body in dorsal view, 6 = mentum, 7 = body in ventral view (part), 8 = podosoma in lateral view. Legs not illustrated

ficant difference exists (Fig. 5). In front of tectopedial field a Y-shaped costula present, between them a well developed, wide lamellar knob present, bearing the conspicuously long lamellar setae. Interbothridial field* well developed, from them a pair of ridges directed to the lamellar knob. Bothridia large, well sclerotised, with basal lobes. Sensillus with long peduncle (Fig. 8) and wide, asymmetrically incrassate head, with some long cilia.

Notogaster: Dorsosejugal margin indistinct medially. Lateral condyles large, well separated. Median part without condyles. Ten pairs of simply curved notogastral setae present.

Lateral part of podosoma (Fig. 8): Exobothridial and acetabular region well sclerotised and granulated above the acetabular region. Exobothridial tubercles form a characteristic, longitudinal ridge.

Ventral parts: Epimeral borders and apodeme normally developed, a wide sternal field present between the epimeral plates medially. Sternal apodeme partly observable also in this region. Epimeres IV with a ring-shaped well sclerotised ridge. Epimeral border IV undulate, along them a Channel of varying depth having pustulate inner surface running parallel with the posterior epimeral border (Fig. 7). Epimeral setae simple, setae 1c located laterally, on the surface of pedotecta I. Anogenital setal formula: 6-1-2-3. Anterior pairs of genital setae longer than the others. Position of adanal setae normal, setae ad1 in paraanal position. All setae in this region mostly smooth. Lyrifissures iad located also in paraanal position.

Legs: Form and chaetotaxy of legs I and IV typical for the family. Setae p of tarsi II-IV simple, setiform. Two ventral setae of tarsus IV dilated, distincly spinose.

* A pair of fields bordered by arcuate, often dentate ribs between the bothridia.

Remarks: The new species is very similar to Unicobelba truncicola (FORSSLUND, 1941), however, is much smaller (354-391 µm in truncicola ), has no large tubercles between the tectopedial fields (present in truncicola ) and has Y-shaped ribs in front of tectopedial fields, which are absent in truncicola (see FORSSLUND 1941).

Etymology: Named after its characteristic prodorsal formation.