Atractides gracilis (Sokolow, 1934)

Pešić, Vladimir, 2014, Checklist of the water mites (Acari, Hydrachnidia) of Korea, with description of one new subgenus and two new species, Ecologica Montenegrina 1 (4), pp. 204-230 : 209-211

Atractides gracilis (Sokolow, 1934)

( Figs. 2 A­E, 3A­F)

New records: South Korea: CR1 Seoul, Dobong stream, 37º41.262'N, 127º01.706'E, 19 m asl., 7.x.2012, Pešić & Choi 8/1/0(2[one juvenile]/1[ovig.]/0 mounted); CR2 Seoul, Ui­dong stream 37º39.554'N, 127º00.249'E, 114 m asl., 7.x.2012, Pešić & Choi 1/1/0; CR9 Jeollabuk Province, Ne myeon Mt, Naebyeansan NP, stream near Naebyeansan Info Center, 35°38'25.623"N, 126°34'53.1438"E, 10.x.2012, Pešić & Choi 1/0/0 (mounted); CR10 Jeollabuk Province, Ne myeon Mt, stream near Silsung temple, 1.7 km to Jiksopolpol falls, Naebyeansan NP, 0.6 km from Naebyeansan Info Center, 35°64'65.978"N, 126°58'62.285"E, 10.x.2012, Pešić & Choi 0/2[juveniles]/0; CR11 Gwangju, Mudeung Mt. , stream, 35°8'50.2584"N 126°59'18.942"E, 11.x.2012, Pešić & Choi 1/0/0; CR18 Gyeongsangbuk Province, Haenggok­ri, river, exposed to sunlight, 36º57.182' N, 129º17.670' E, 24.v.2013 Pešić & Karanović 0/1/0 .

Records from Korea: Gangwon Province – Kim and Chung (1991).

Morphology

General features — Integument with very fine striation; muscle insertions unsclerotized. Coxal field: mediocaudal margin of Cx­I equally convex, apodemes of Cx­II in an obtuse angle. Genital field: Ac in a weakly curved line. Excretory pore slightly sclerotized ( Fig. 3C ); Vgl­1: separate from Vgl­2. Palp: without sexual dimorphism, P­2­3 ventral margins straight, P­3 (L/H ratio 3.1­3.6) and P­4 (L/H ratio 6.0­6.6) slender, P­4 ventral margin weakly extended near proximal seta insertions, sword seta near distoventral seta ( Figs. 2 D­E, 3E­F). Legs: I­L­5 protruding between ventral seta and S­1 insertion, setae S­1 and ­2 strongly heteromorphic and widely distanced, S­1 long and very slender, S­2 shorter, enlarged and with pointed tip, I­ L­6 long and very slender, equally narrow from the base to the tip.

Measurements

Male (from CR1, in parentheses specimens from CR9) – Idiosoma L/W 600 (538)/430 (420), glandularia diameter 29 (26); coxal field: L 350 (325); Cx­III W 370 (350); Cx­I+II medial L 102 (114), lateral L 203 (202); genital field L/W 113 (108)/110 (112), L Ac 1­3: 32 (27­28), 35 (30­31), 40 (31­34). Genital field with anterior margin slightly convex, posterior margin indented. Ejaculatory complex L (115).

Palp: palp total L 346 (352­353), dL/H, dL/H ratio: P­1, 29/24, 1.22 (31/25, 1.25); P­2, 60/29, 2.07 (61/31, 2.0); P­3, 97/31, 3.14 (94/29, 3.2); P­4, 121/20, 6.04 (125/20, 6.3); P­5, 39/10.5, 3.7 (41­42/11, 3.7); L ratio P­2/P­4 0.5 (0.49). Gnathosoma L 119 (112), chelicera total L 162 (154).

Legs: I­L­5 dL 229 (229), vL 145 (135), dL/vL ratio 1.6 (1.7), maximum H 42 (43), dL/maximum H 5.5 (5.3), S­1 L 126 (134), L/W ratio 12.0 (12.4), S­2 length 91 (94), L/W ratio 7.4 (7.2), distance S­1­2 40 (48), L ratio S­1/2 1.4 (1.43); I­L­6 dL 189 (186), central H 14.5 (14.5), dL/central H ratio 13.0 (12.8); L ratio I­L­5/6 1.21 (1.23).

Female (from CR1) – Idiosoma L/W 880/670, glandularia diameter 31; coxal field: L 391; Cx­III W 484; Cx­I+II medial L 113, lateral L 223; genital field L/W 146/165, genital plate L 111­112, L Ac 1­3: 32­ 39, 34­38, 29­36.

Palp: palp total L 403, dL/H, dL/H ratio: P­1, 32/25, 1.3; P­2, 72/35, 2.0; P­3, 117/32, 3.6; P­4, 139/21, 6.6; P­5, 43/12, 3.5; L ratio P­2/P­4 0.52.

Legs: I­L­5 dL 277, vL 154, dL/vL ratio 1.8, maximum H 52, dL/maximum H 5.3, S­1 L 164, L/W ratio 12.5, S­2 length 109, L/W ratio 7.1, distance S­1­2 66, L ratio S­1/2 1.5; I­L­6 dL 234, central H 14.5, dL/central H ratio 1.6; L ratio I­L­5/6 1.18.

Remarks. The description of Atractides gracilis was based on a single female from the Primory Territory, in Russian Far East. Later on, female A. gracilis were reported by Imamura (1953) from Japan and Kim and Chung (1991) from Korea, but until now no males have been found. The specimens from Korea match the original description, and the following characters of the males collected together with female A. gracilis indicate conspecifity: long and very slender I­L­6, setae S­1 and ­2 heteromorphic and widely distanced, excretory pore slightly sclerotized, palp with P­2­3 ventral margins straight, and slender P­3 (L/H ratio 3.1­ 3.6) and P­4 (L/H ratio 6.0­6.6).

Habitat: Rhitrobiont.

Distribution: Russia (Primory Territory), Japan (Hiroshima), Korea.

Figures

Figure 2.Atractides gracilis (Sokolow, 1934), male (A, C, E – specimen from CR1; B, D – specimen from CR9): A = coxal field; B = genital field, Vgl­1/2 and excretory pore; C = I­L­5 and ­6; D = palp, medial view (P­1 lacking); E = palp, lateral view. Scale bars = 100µm.

Figure 3.Atractides gracilis (Sokolow, 1934), female, CR1 Dobong stream: A = coxal field; B = genital field; C = excretory pore; D = I­L­5 and ­6; E = palp, lateral view; E = P­4, medial view. Scale bars = 100 µm.