Atractides (Polymegapus) kuehnei ( K. Viets, 1911 )

Pešić, Vladimir & Smit, Harry, 2015, Water mites of the genus Atractides Koch, 1837 (Acari: Hydrachnidia: Hygrobatidae) from Ghana, Zootaxa 3911 (3), pp. 343-356 : 348-350

Atractides (Polymegapus) kuehnei ( K. Viets, 1911)

( Figs. 4A–F )

Megapus kühnei K. Viets 1911: 493 .

Material examined. Ghana: Akaa Falls, 6º 10.516 N, 0º 11.723 W, alt. 180 m asl, 9.iii.2011, Smit 1/0/0 (mounted); Small rainforest stream upstream Sagyimase, Atewa Hills, 6º 13.964 N, 0º 33.116 W, alt. 654 m asl., 8.iii.2011, Smit 0/1/0 (mounted); Fuller Falls, 8º 04.975 N, 1º 47.842 W, alt. 189 m asl, 6.iii.2011, Smit 1/2(one juvenile)/1; Amedzofe Falls, 6º 50.656 N, 0º 26.868 E, alt. 599 m asl., 20.ii.2013, Smit 1/0/0; Kue River, Kyaboba NP, 8º 31.087 N, 0º 36.049 E, alt. 208 m asl., 25.ii.2013, Smit 0/1/0.

Morphology. Integument dorsally striated, muscle insertions unsclerotized. Coxal field: medioposterior margin of Cx-I+II truncated, Cx-II apodemes strong, in an acute angle, extending over the posteromedial margin of Cx-I+II, suture line Cx-III/IV in medial part nearly straight. Excretory pore smooth; Vgl-1 separated from Vgl-2. Palp without sexual dimorphism, ventral margin of P-2 slightly convex, P-3 slightly concave, P-4 sword seta shortened and stout, inserting proximally from proximoventral seta ( Figs. 4C–D ). I-Leg ( Fig. 4E ): I-L-5 longer dorsally than ventrally, setae S-1 and S-2 similar in length, S-2 thicker than S-1; IV-L-5 with two swimming setae at distal margin and nearly long as IV-L-6 ( Fig. 4F ). Male: Genital field ( Fig. 4B ): anterior margin convex, posterior margin truncate, not indented, Ac in a weakly curved line. Female: Genital plates on the level of postgen, short and triangular ( Fig. 4A ).

Measurements. Male (from Akaa Falls)—Idiosoma length/width 338/313, glandularia maximum diameter 22; coxal field: length 209; Cx-III width 221; Cx-I+II medial length 106, lateral length 158; genital field length/ width 51/69, length Ac 1–3: 10–15, 12–15, 17–18; ejaculatory complex length 74.

Palp: Total length 217, dorsal length/height, dorsal length/height ratio: P-1, 17/21, 0.81; P-2, 54/28, 1.95; P-3, 37/24, 1.52; P-4, 75/19, 4.0; P-5, 34/11, 3.2; length P-2/P-4 ratio 0.72. Capitulum ventral length 77. Legs: I-L-5 dorsal length 83, ventral length 70, dorsal length/ventral length ratio 1.19, maximum height 31, dorsal length/ maximum height 2.64, S-1 length 42, length/width ratio 9.2, S-2 length 42, length/width ratio 5.4, distance S-1-2, 2, length ratio S-1/2, 1.01; I-L-6 length 54, central height 14, length/central height ratio 4.0, proximal height 21, length/central height ratio 2.6; length I-L-5/6 ratio 1.54.

Female: Idiosoma length/width 472/406, glandularia maximum diameter 24; coxal field: length 250; Cx-III width 284; Cx-I+II medial length 125, lateral length 181-188; genital field length/width 109/113, pregenital sclerite width 75, genital plates length 51-54, Ac 1-3: 20-21, 22-22, 22; egg (n = 1) maximum diameter 105. Palp: Total length 256, dorsal length/height, dorsal length/height ratio: P-1, 23/26, 0.88; P-2, 65/39, 1.7; P-3, 39/29, 1.34; P-4, 92/23, 4.0; P-5, 37/13, 2.9; length P-2/P-4 ratio 0.71. Capitulum ventral length 77; chelicera total length 137. Legs: I-L-5 dorsal length 100, ventral length 79, dorsal length/ventral length ratio 1.27, maximum height 29, dorsal length/maximum height 3.5, S-1 length 39, length/width ratio 8.4, S-2 length 39, length/width ratio 5.0, distance S- 1-2, 0, length ratio S-1/2, 1.0; I-L-6 length 61, central height 14, length/central height ratio 4.4; length I-L-5/6 ratio 1.64.

Remarks. The description of Atractides kuehnei ( K. Viets, 1911) was based on a single male from a stream in the village Owe (near the Muyuka town in South West Province of Cameroon). Two years later a detailed description of the female (collected from the type locality, and two streams near the Kumba town) was given by K. Viets (1913). Atractides kuehnei resembles A. putihi Wiles, 1991 (E Asia) and A. abruptus Cook, 1966 ( Liberia) in having I-L-5 with the ventral margin shorter than the dorsal margin. These three species possibly represent an early evolutionary stage, with the condition of I-L typical for the subgenus Polymegapus (I-L-5 ventrally projecting, ventral length> dorsal length) not yet fully developed.

Distribution. Cameroon ( K. Viets, 1911, 1913); Ghana (our study).

Figures

FIGURE 4 A – F. Atractides kuehnei (K. Viets, 1911) (B – C, E = male from Akaa Falls, A, D, F = female from small rainforest stream upstream Sagyimase): A = idiosoma, ventral view; B = genital field; C = palp, medial view; D = palp, medial view (P- 1 lacking); E = I-L- 5 and - 6; F = IV-L- 6. Scale bars = 100 Μm.