Atractides

Gerecke, Reinhard, 2003, Water mites of the genus Atractides Koch, 1837 (Acari: Parasitengona: Hygrobatidae) in the western Palaearctic region: a revision, Zoological Journal of the Linnean Society 138, pp. 141-378 : 253

ATRACTIDES PRIMITIVUS ( WALTER, 1947)

Megapus primitivus Walter, 1947

Syn. to A. pumilus ( Szalay, 1946) : syn. nov.

Type series: Lectotype ♀, here designated, NHMB Megapus primitivus ♀ Walter Aurig 25.7.1943 Coll. Chappuis; XV/56; Typus; leg. Chappuis Grundwasser Aurig unweit Sibiu Rumänien 25.7.43; D.III b 54 P3.1556 Typ ♀. State of conservation: gnathosoma separate, lateral, both palps separate, all legs in situ, but clearly visible . Paralectotype ♂: NHMB as lectotype, but XV/57 and Pr.1557 Typ ♂. State of conservation: idiosoma laterally crushed, Cx-1 + 2 medially pushed one upon the other, both I-L- and left III/IV-L missing, gnathosoma separate lateral, both palps isolated.

Discussion: In his description, Walter did not discuss relationships and diagnostic features, and clearly was not aware of the existence of the very similar A. pumilus , described from a collecting site about 100 km from the locus typicus of A. primitivus . Both species agree perfectly in the shape of coxae, I-L, genital field and mouthparts. The flattened P- 4 in Szalay’s (1946) figures 3(c,d) is a defect often found in weakly sclerotized juveniles. The few available measurements of A. pumilus indicate that Szalay’s specimen was smaller, possibly a juvenile, but the low total L of palp (190 Mm) cannot increase markedly with age. Szalay’s measurements were frequently inaccurate: from his data, a L ratio P-2/3 of 1.23 can be deduced, but examination of his figure produces 1.0 (as found also in the types of A. primitivus ). The most important difference concerns the sclerotization and extension of muscle attachments. In the type of A. pumilus , the postoc seta is not included in the anterior pair of dorsal sclerites, D-4 is not fused with Dgl-5, and D-5 as well as V-1–3 remain unsclerotized. Among the specimens from Harz and Switzerland, no such weakly sclerotized juveniles were found; however, there was considerable variability in the extension of idiosomal sclerites, which in one case were found to be much more extended than in the type series. In view of the age-dependent extension of muscle attachment sclerites, differences of this type are not suitable for species discrimination, and A. primitivus should be considered a synonym of A. pumilus .

ATRACTIDES DENTICULATUS ( WALTER, 1947)

( FIG. 50A–G )

Megapus denticulatus Walter, 1947

Atractides microphthalmus [err.] Rensburg, 1971

Type series: Holotype ♀, NHMB, Boiron, 13.8.1945 Coll. Walter (caption by Bader); Megapus denticulatus Walter D III b.80 Pr. 1644 ♀ Typus Boiron b. Anex 13.8.1945 (caption by Walter). State of conservation: nearly perfect, but left III-L missing, idiosoma laterally compressed, and genital field in oblique position.

Material examined: Luxembourg, coll. Gerecke & Schrankel. LUX Int 4, Ösling, Hoscheid, Schlënnerbaach unter Chappelle St. Michel , 300 m, 07.08.1998 Karaman-Chappuis, 1 ♂, 3 ♀ ; LUX Int 10, Ösling, N Kalborn, R. de Janschleid oberhalb Mündung Roupelsbaach , 23.04.1999 Bou-Rouch, 1 ♀ ; LUX Int 11, Ösling, E Fischbach, Stroumbaach, 335 m, 23.4.1999 Bou- Rouch , 1 ♂, 2 ♀ ; Germany, Schönbuch ( TÜ) Goldersbach, 27.03.1989 Gerecke, D 315 oberhalb Teufelsbrücke 1 ♂ ; D 316 unterhalb Bettelwegbrücke 1 ♂, 1 ♀. Switzerland, NHMB, Rensburg Präp. 12, 18.8.1968 1 ♀ ; Schiess, Lützel, hyp. 1 ♂, 1 ♀.

Description:

General features dorsal integument: striated (9/10); muscle attachments: Postoc, Dgl-3 and D-

1 fused to a small, T-shaped platelet; D-2 a small sclerotized knob; Dgl-4 fused with D-3; D-4 unfused, the largest of the dorsal plates; V-4 roundish, V-2 not visible, V-3 fused with Vgl-4

coxal field: Cx-1 with a subcuticular mediocaudal processus, and a less extending epicuticular appendix bearing a longish medial pit, most coxal setae fine and long genital field: Ac in a weakly curved line

I-L: little modified, I-L-5 with S-1 and -2 similar in shape and close to each other, I-L-6 nearly straight, distally thickened, with strong claw.

IV-L: IV-L-5 with a long, fine, distal hair excretory pore: sclerotized; Vgl-1: fused to Vgl-2

palp: weak sexual dimorphism; P-2 and P-3 robust, both with strongly convex ventral surface covered by fine denticulation; P-4 rather slender, ventral margin 1: 1: 1, with strong ventral denticle near proximal hair, and less protruding but well visible denticle near distal hair, sword seta enlarged, near the proximoventral hair; P-5 longish

Males

Specimens from Luxembourg genital field: circular, with slightly flattened caudolateral and posterior margins, gonopore short and enlarged; genital setae: 34, anteriomedially arranged in a pair of small circles, not flanking the gonopore palp: P-4 more robust than in females idiosoma L/W 450/340; glandularia 18

coxal field L 198; Cx-3 W 234; Cx-1 + 2 mL 81, IL 134, W 192

I-L-5 dL 113, vL 92, dL/vL 1.23, HA-HC 26, 30, 33, dL/HB 3.77

S-1 L 61, L/ W 10.2 S-2 L 55, L/ W 11.0, interspace 5, L S-1/2 1.11

I-L-6 L 95, HA-HC 17, 16, 21, dL/HB 5.94; L I-L-5/6 1.19

genital field L/W 83/78, Ac-1–3 L 30, 23, 23

gnathosoma –; chelicera –

Figures

Figure 50. Atractides denticulatus, A–D holotype ♀, E-G specimens from Luxembourg. A, ♀ I-L-5 and -6; B, ♀ distal part of IV-L-5 and IV-L-6; C, ♀ palp, medial view; D, ♀ coxal field, E, ♀ genital field; F, ♂ dorsal idiosoma; G, ♂ genital field. Scale bars = 100 µm.