Atractides

Pešić, Vladimir & Smit, Harry, 2015, Water mites of the genus Atractides Koch, 1837 (Acari: Hydrachnidia: Hygrobatidae) from Ghana, Zootaxa 3911 (3), pp. 343-356 : 354-355

Atractides sp.

( Fig. 7A–E )

Material examined. Ghana: stream Asukuma, Kakum NP, 5º 26.995 N, 1º 25.071 W, alt. 131 m asl., 12.ii.2013, Smit 1/0/0 (mounted).

Description. Male. Dorsal muscle insertions sclerotized ( Fig. 7A ): unpaired anteromedial plate, anteriorly pointed, with undulating lateral and straight caudal margin including prefr, postoc, Dgl-3, Dgl-4, D-1 and D-2, unpaired posterior plate with straight anterior margin including Dgl-5 and D-4, other glandularia on extended platelets. Coxal field: ventral surface covered by an extended shield including coxae, Vgl-3/4, genital field, excretory pore and Vgl-1+2 ( Fig. 7B ). Palp: ventral margin of P-2 and P-3 straight, P-4 sword seta pointed, little enlarged, but not hair-like, inserting distal to distoventral seta, P-5 without “cheeks” ( Fig. 7C ). Legs: I-L-5 S-1 and -2 closely together; I-L-6 strong and thick, weakly curved, narrowed in the centre of the segment, maximum height at base of claw furrow ( Fig. 7D ); claws with ventral and dorsal clawlets.

Measurements. Idiosoma length/width 406/341; large dorsal anteromedial plate length/width 274/225, maximum diameter of dorsal posterior plate 165; ventral shield length/width 378/311; Cx-III width 234; genital field: width between most lateral pair of Ac 87; length Ac 1–3: 15–16, 19, 18–19.

Palp: Total length 176, dorsal length/height, dorsal length/height ratio: P-1, 17/14, 1.2; P-2, 38/25, 1.53; P-3, 39/20, 1.93; P-4, 56/14, 4.1; P-5, 26/9, 2.8; length P-2/P-4 ratio 0.67. Capitulum ventral length 101; chelicera total length 139, claw length 46, basal segment length 115, length basal segment/claw ratio 2.5.

Legs: I-L-5 dorsal length 72, ventral length 55, dorsal length/ventral length ratio 1.31, maximum height 25, dorsal length/maximum height 2.94, S-1 length 29, length/width ratio 9.4, S-2 length 32, length/width ratio 8.1, distance S-1-2, 4, length ratio S-1/2, 0.9; I-L-6 length 62, central height 17, proximal height (HA sensu Gerecke 2003) 23, length/central height ratio 3.58, length/proximal height ratio 2.65; length I-L-5/6 ratio 1.18.

Remarks. The single male examined from Ghana shares with A. tuberipalpis ( K. Viets. 1913) the similar formation of the ventral shield, including excretory pore and all Vgl, but not incorporating Lgl-4. The latter species clearly differs in the arrangement and size of dorsal sclerites (compare Figs. 5A and 7A ). However, as mentioned above, in males, this character may show considerable age-dependent variation. Since further material is not available, and a revision of A. testudo -group is required (see above under A. cf. tuberipalpis ) a final decision on the question if this specimen represents an undescribed species can not be made.

Figures

FIGURE 7 A – E. Atractides sp., male, stream Asukuma: A = idiosoma, dorsal view; B = idiosoma, ventral view; C = palp, medial view (P- 1 lacking); D = capitulum and chelicera; E = I-L- 5 and - 6. Scale bars = 100 Μm.

FIGURE 5 A – I. Atractides cf. tuberipalpis (K. Viets, 1913), male (A – C, E – I – specimen from Nubui River, D – specimen from Laboun River): A – B Photographs: A = dorsal shield; B = ventral shield. C = posterior part of the ventral shield; D = posterior margin of the ventral shield; E = Dgl- 1; F = ejaculatory complex; G = palp, lateral view; H = I-L- 5 and - 6; I = IV-L claw. Scale bars = 100 Μm.