Atractides linearis (Lundblad, 1927)

Pešić, Vladimir, Smit, Harry & Gerecke, Reinhard, 2011, New records of water mites of the genus Atractides Koch, 1837 (Acari: Hydrachnidia, Hygrobatidae) from South Africa, with descriptions of five new species, Zootaxa 2986, pp. 1-54 : 8-13

Atractides linearis (Lundblad, 1927)

( Figs. 7–10 )

Megapus linearis Lundblad 1927a: 333 .

Material examined. South Africa, Western Cape province: SA 9 25/24 /2 (1/1/1 mounted). KwaZulu-Natal province: SA 12 1/2 /0 (1/1/0 mounted); SA 17 0/1/0; SA 18 1/0/0; SA 22 0/1/0; SA 24 2/2 /0; DC 92 84 0/1/0. Limpopo province: SA 25 3/1 /0. Mpumalanga province: DC 78 84 0/1/0; DC 84 84 10/6 /0; DC 85 84 1/0/0; DC 86 84 1/0/0; DC 87 84 2/21 /0 (1/0/0 mounted). Eastern Cape province: DC 103 84 4/28 /4 (0/0/1 mounted).

General features. Dorsal integument lineated; muscle attachments unsclerotized. Coxal field: apodemes Cx-II in an acute angle. Genital field: Ac in a weakly curved line. Excretory pore: unsclerotized; Vgl-1 close to Vgl-2 and often fused (in older specimens). Palp: sexual dimorphism, in both sexes P-2 distoventrally protruding; P-4 sword seta between ventral hairs, nearer to distoventral hair. I-L-5 distally protruding near insertion S-1, S-1 and S-2 bluntly pointed, interspaced, S-2 basally enlarged; I-L-6 curved, inflated proximally, from the centre to the claw furrow with parallel dorsal and ventral margins; leg claw without dorsal clawlets.

Morphology. Male (SA 9, in parentheses SA 12, in square parentheses DC 87 84). Idiosoma L/W (423)/(328); glandularia maximum diameter 23 (19) [22]; coxal field L 288 [295]; Cx-III W 328 [347]; Cx-I+II mL 100, lL 188. Genital field ( Fig. 7A , 8A ): anterior margin slightly concave; L/W 91 (97) [92]/102 (115) [99]; L Ac 1-3: 24 (29– 32) [30], 28 (30–31) [29–32], 32 (38–39) [29]; ejaculatory complex L (103) [99].

Palp ( Figs. 7C , 8C ): total L 254 (229) [265], dL: P-1, 28 (28) [27]; P-2, 62 (52) [59]; P-3, 54 (49) [60]; P-4, 81 (71) [87]; P-5, 29 (29) [32]; L ratio P-2/P-4, 0.77 (0.73) [0.68]; P-2 ventral margin distally protruding, P-3 stout; capitulum vL [132].

I-L ( Figs. 7B , 8B ): I-L-5 dL 159 (137) [165], vL 100 (91) [105], dL/vL ratio 1.59 (1.51) [1.57], HB 45 (41) [46], dL/HB 3.53 (3.34) [3.59], S-1 L 75 (67) [82], L/ W 9.7 (7.9) [9.7], S-2 L 63 (54) [69], L/ W 5.1 (4.4) [5.2], distance S-1-2, 17 (12) [21], L ratio S-1/2, 1.2 (1.24) [1.2]; I-L-6 L 115 (100) [124], HB 18 (18) [19], L/HB ratio 6.5 (5.6) [6.7]; L ratio I-L-5/6, 1.38 (1.37) [1.33].

Female (SA 9, in parentheses SA 12). Idiosoma L/W L/W (531)/(397); glandularia maximum diameter 25 (22); coxal field L 363 (303); Cx-III W 420 (356); Cx-I+II mL 105 (91), lL 219 (195). Genital field ( Fig. 9B ): L/W 158/ 161; genital plate L 109 (108–109); pregen W 89, L Ac 1–3: 35 (35–41), 40 (35–40), 32 (34–35).

Palp ( Fig. 7D ): total L 332 (273), dL: P-1, 35 (30); P-2, 74 (63); P-3, 85 (66); P-4, 101 (84); P-5, 37 (30); L ratio P-2/P-4, 0.73 (0.75); palp much slender than in male, P-2 with a ventrodistal hump; capitulum vL 141; chelicera total L 215.

I-L ( Fig. 9A ): I-L-5 dL 215 (175), vL 137 (115), dL/vL ratio 1.57 (1.52), HB 57 (48), dL/HB 3.77 (3.64), S-1 L 103 (77), L/ W 10.1 (10.0), S-2 L 80 (72), L/ W 5.0 (5.2), distance S-1-2, 29 (22), L ratio S-1/2, 1.29 (1.07); I-L-6 L 154 (113), HB 18.5 (16), L/HB ratio 8.3 (7.0); L ratio I-L-5/6, 1.4 (1.54).

Deutonymph (collected at SA 9 and suspected to represent this species). Idiosoma L/W 303/229; integument dorsally lineated; muscle attachments unsclerotized; coxal field L 169; Cx-III W 199; Cx-I+II mL 47, lL 104; provisional genital field with two pairs of Ac ( Fig. 10A ), L/W 47/55; excretory pore smooth; Vgl-1 not fused to Vgl-2

Palp: total L 150, dL: P-1, 16; P-2, 33; P-3, 31; P-4, 48; P-5, 22; L ratio P-2/P-4, 0.69.

I-L ( Fig. 10B ): I-L-5 dL 89, vL 70, dL/vL ratio 1.27, HB 31, dL/HB 2.9, S-1 L 45, L/ W 8.8, S-2 L 43, L/ W 6.2, distance S-1-2, 0, L ratio S-1/2, 1.05; I-L-6 L 63, HB 15, L/HB ratio 4.1; L ratio I-L-5/6, 1.39.

Remarks. Due to the lineated integument, unsclerotized dorsal muscle attachments, unsclerotized excretory pore, P-2 distoventrally protruding in both sexes, and I-L-5 with S-1 and S-2 bluntly pointed and with a narrow setal interspace, the specimens examined from South Africa show general conformity with A. linearis (Lundblad, 1927) . Considerable variation is found in the fusion of Vgl-1 and -2 (Vgl-1 free or fused to the medial margin of Vgl-2, in some cases asymetrically fused only on one side, but free on the other, see Fig. 8A ) and in the anterior margin of the male genital field, being straight to slightly concave ( Fig. 7A ) or more indented ( Fig. 8A ).

Distribution. Kenya: Lundblad (1927a, b, 1952); South Africa: Eastern Cape province: K.O. Viets (1964a), present study; Western Cape province: present study; Mpumalanga province: K.O. Viets (1964a), present study; Limpopo province: present study.

Figures

FIGURE 7 A – D. Atractides linearis (Lundblad, 1927) (A – C = male, D = female), Grobbelaars River: A = idiosoma, ventral view; B = I-L- 5 and - 6; C = palp, medial view; D = palp, lateral view. Scale bars = 100 μm.

FIGURE 8 A – C. Atractides linearis (Lundblad, 1927), male, Pholelana River: A = genital field, excretory pore and Vgl- 1 and - 2; B = I-L- 5 and - 6; C = palp, medial view. Scale bar = 100 μm.

FIGURE 9 A – B. Atractides linearis (Lundblad, 1927), female, Grobbelaars River: A = I-L- 5 and - 6; B = genital field. Scale bar = 100 μm.

FIGURE 10 A – B. Atractides linearis (Lundblad, 1927), deutonymph, Grobbelaars River: A = idiosoma, ventral view; B = I - L- 5 and - 6. Scale bar = 100 μm.