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 : 201

ATRACTIDES CORIACEUS (K. VIETS, 1925)

Megapus coriaceus K. Viets, 1925

Syn. to A. walteri (K. Viets, 1925) : Lundblad, 1956

Type series: Holotype ♂ SMF 3256 Atractides subasper coriaceus ♂ Viets Type; Tirol Kasbachtal Quelle 26.8.1923 Viets coll. 3256. State of conservation: mounting fluid densely filled with precipitated material, probably transferred to a second embedding fluid that has produced additional precipitation; both IV-L, one I-L separate, gnathosoma, chelicerae and Gsk missing, both palps lateral.

Discussion: Due to the presence of a large border of secondary sclerotization at the margins of Cx-4, Viets initially planned to describe this taxon as a subspecies of A. subasper , a species very different from many points of view. In the discussion of the original description, he underlined the following diagnostic characters in males as compared with A. walteri : integument thicker and with reticulation in deeper layers, ventral idiosoma without lineated integument, but with regularly arranged groups of 6–8 pores; diameter of glandularia large (40 Mm); anterior margin of genital field not indented, mediocaudal indentation filled with porous chitin, genital field with maximum W (125 Mm) on the level of Ac-1. Later, the author himself (with a question mark) transferred the specimen on which the description of the female was based to another new species ( A. separatus: K. Viets, 1931 ). As clearly indicated by comparative studies of large populations of A. walteri ( Lundblad, 1956; pers. observ.) all the above-mentioned characters are not suitable for distinguishing species, but characterize a rather juvenile (holotype of A. walteri ) and a quite old (holotype of A. coriaceus ) specimen of the same species. As all transitions can be observed between these two character combinations in natural populations, the synonymization of A. coriaceus with A. walteri , first proposed by Lundblad (1956) is correct.

ATRACTIDES PANNICULATUS (K. VIETS, 1925)

( FIGS 4B,C , 5D–F , 6G,H , 9D,E , 10B , 30A–F )

Megapus panniculatus K. Viets, 1925

Syn. A. mitisi ( Walter, 1944) : syn. nov.

Type series: Lectotype ♂, here designated, SMF 3267 Atractides panniculatus ♂ ♀ (Viets) Type Tirol Qu. i. Wattental b. Innsbruck 27.8.23 Viets leg. State of conservation: containing 2 ♂, 2 ♀; one of the ♂ with only right I-/II- L in situ, the remaining legs separate, gnathosoma and chelicerae in dorsal view, both palps separate lateral. This specimen described in K. Viets (1925: fig. 64) and therefore selected as lectotype . Paralectotypes on the same slide, ♂ (with only right II-/IV-L in situ) and 2 ♀; SMF 3275 , labelled like lectotype , 2 ♂, one entire, the other dissected.

Material examined: Germany, Upper Bavaria, and Italy, Trentino-Alto Adige, from a research project on Alpine springs (collecting sites in Crema et al., 1996) 35/18/0.

Description:

General features dorsal integument: lineated (4/10); muscle attachments: unsclerotized coxal field: sexual dimorphism

I-L: I-L-5 moderately thickened distally, sword setae distanced, with knifelike lamellar inner margins, S-1 with parallel margins in the distal third and tip obliquely cut off, S-2 enlarged; I-L-6 long and slender, slightly thickened basally, with parallel dorsal and ventral margins from the centre to the claw pit genital field: Ac in a triangle, large, Ac-3 (often also Ac-2) protruding over the sclerite margin excretory pore: smooth; Vgl-1: not fused to Vgl-2

palp: weak sexual dimorphism, ventral margin P-2 distally protruding, P-3 straight, P-4 2: 3: 1, sword seta near distal hair.

Males

Paralectotype SMF 3267 , in parentheses specimens from Berchtesgaden coxal field: Vgl-3 fused to Cx-4

genital field: anterior margin of primary sclerotization slightly indented, a border of secondary sclerotization truncate, slightly convex, often with a knob-shaped medial projection, posterior margin indented by an acute angle; genital setae: 35

palp: ventral margin P-2 often with irregular rugosity due to fine transverse furrows, distal protrusion rounded, P-4 slightly protruding near proximoventral hair, 2: 3: 1, sword seta short and curved.

idiosoma L/W 630/470; glandularia 33

coxal field L 360; Cx-3 W 392; Cx-1 + 2 mL 135, IL 240, W 310

I-L-5 dL 228, vL 156, dL/vL 1.46, HA-HC 58, 65, 85, dL/HB 3.51

S-1 L 121, L/ W 12.1, S-2 L 90, L/ W 6.0, interspace 32, L S-1/2 1.34

I-L-6 L 165, HA-HC 28, 20, 19, dL/HB 8.25; L I-L-5/6 1.38

genital field L/W 183/196, Ac-1–3 L 64(41–56)-79(47–61)-68(45–62)

gnathosoma vL 156; chelicera L 248, L/H 5.28, bS/claw 2.26

Figures

Figure 4. Types of integument morphology in Atractides, SEM photographs. A, finely striated (A. macrolaminatus ♂, Berchtesgaden), scale bar = 4 µm; B, lineated (with slit organ and glandulare) (A. panniculatus ♀, Berchtesgaden), scale bar = 40 µm; C, ditto, detail (with glandulare), scale bar = 10 µm; D, papillate (A. walteri ♀, Berchtesgaden), transition area between striated (at right, upper margin) and papillate (at left lower margin), scale bar = 40 µm; E, ditto, detail, scale bar = 2 µm; F, porosity of sclerified surface of Cx-4 (A. nodipalpis ♂, Goldersbach, SW Germany).

Figure 5. Idiosoma morphology of Atractides, SEM photographs, all scale bars = 100 µm. A, anterior view of the dorsum of A. walteri ♂ (Berchtesgaden), soft-skinned muscle insertions are visible as shallow pits; B, anterior view of the dorsum of A. macrolaminatus ♂ (Berchtesgaden), with sclerotized muscle insertions visible as enlarged plates partly covered by membranous integument; C, ventrum of A. nodipalpis ♂ (Goldersbach), showing extension of soft membrane and coxal sclerites; note the presence of a sclerified bridge between anteromedial margin of Cx-1 and gnathosomal base; D, coxal field and gnathosoma of A. panniculatus ♀ (Berchtesgaden); E, posterodorsal view of A. panniculatus ♀ (Berchtesgaden); note the long setae of Dgl-3 and Dgl-4; F, genital area of A. panniculatus ♂ (Berchtesgaden) – Vgl-1 not fused with Vgl-2, excretory pore unsclerified.

Figure 6. Morphology and terminology of Atractides (A–F, A. walteri, Berchtesgaden). A–D, male; A, gnathosoma, lateral view; B, gnathosoma, ventral view; C, chelicera, lateral view; D, palp, medial view; E, F, female; E, palp, medial view; F, genital field, terminology: see ‘Anatomical abbreviations’; G, H, A. panniculatus ♂ Berchtesgaden, ejaculatory complex; G, anterior view; H, lateral view.

Figure 9. Morphology of the first leg in Atractides, SEM photographs. A, A. nodipalpis ♂ (Goldersbach), anterior view, scale bar = 100 µm; B, A. nodipalpis ♂ (Goldersbach), insertion of S-1 and -2, scale bar = 20 µm; C, A. nodipalpis ♀ (Goldersbach), basal setae-bearing groove of I-L-6, scale bar = 20 µm; D A. panniculatus ♀ (Berchtesgaden), insertion of sword setae on I-L-5, scale bar = 20 µm; E, A. panniculatus ♀ (Berchtesgaden), I-L-6, ventrodistal setae and claws, scale bar = 10 µm; F, A. macrolaminatus ♂ (Berchtesgaden), insertion of sword setae I-L-5 and swollen articulation membrane, scale bar = 10 µm.

Figure 10. Morphology of the palp in male Atractides, SEM photographs. A, A. nodipalpis (Goldersbach), ventral protuberance of P-2, scale bar = 20 µm; B, A. panniculatus (Berchtesgaden), distal part of P-4 with pennate medial seta, and P-5, scale bar = 20 µm; C, A. nodipalpis (Goldersbach) P-4 and P-5, scale bar = 40 µm; D A. walteri (Berchtesgaden), P-5 claws, scale bar = 4 µm; E, A. nodipalpis (Goldersbach), P-4, insertion of medial seta, scale bar = 4 µm; F, A. nodipalpis (Goldersbach), ventral protuberance, ventral view, scale bar = 10 Mm.

Figure 30. Atractides panniculatus. A, paralectotype ♀ SMF 3267; B, ♀ Berchtesgaden; C–F lectotype ♂ SMF 3267. A, ♀ palp, medial view; B, ♀ genital field; C, ♂ palp, medial view; D, ♂ I-L-5 and -6; E, ♂ coxal field; F, ♂ genital field. Scale bars = 100 µm.