Atractides (Atractides) constrictus (Sokolow, 1934) Sokolow, 1934

Pesic, Vladimir, Semenchenko, Ksenia A. & Lee, Wonchoel, 2015, Further studies on water mites from Korea, with description of two new species (Acari, Hydrachnidia), ZooKeys 507, pp. 1-24 : 6-7

Taxon classification Animalia Trombidiformes Hygrobatidae

Atractides (Atractides) constrictus (Sokolow, 1934) stat. n. Figs 8, 9, 10

Megapus nodipalpis constrictus Sokolow 1934: 361. Synonymy.

Material examined.

SOUTH KOREA: CR22 Gangwon Province, Chiaksan NP, Silim town, stream (shaded, stones and gravel substrate), 37°17.081'N, 128°15.389'E, 25.v.2013 Pešić & Karanović 5/0/0 (1/0/0 mounted). RUSSIA: Primory Territory, Khasansky District, "Kedrovaya Pad National Nature Biosphere Reserve", Sea of Japan basin, Kedrovaya River (depth 12-50 cm; substrate: boulders, cobbles, pebbles), 43°06.056'N; 131°33.310'E; 27.vi.1993 Tiunova 4/15/0 (2/2/0 mounted); Primory Territory, Partizansky District, Partizanskay River basin, Tigrovaya River (substrate: cobbles, pebbles, sand), 43°11.401'N; 133°12.660'E, 12.vi.2010 Semenchenko & Sidorov 2/3/2 (1/1/2 mounted).

General features.

Adults. Integument striated, muscle insertions unsclerotized. Setae Dgl-1, Dgl-3, Dgl-4 and Lgl-2 longer than other dorsal setae; Preoc. and Postoc. without glandularia (Fig. 9 A–C). Coxal field: caudal margin Cx-I convex, apodemes of Cx-II directed laterally (Figs 8A, 9D). Excretory pore smooth; Vgl-1 fused to Vgl-2, separate in juvenile specimens. Gnathosoma elongated (Figs 9F). Palp with strong sexual dimorphism in P-2 and -4, P-4 sword seta between ventral setae. Legs without swimming setae, posterior legs slender (Fig. 9I). Leg claws with near-equal denticles (Fig. 9J). I-L-5: S-1 longish, blunt, S-2 basally enlarged, pointed; I-L-6 curved, basally thickened (Figs 8B, 9H, 10C). Male. Genital field: both anterior and posterior margins deeply indented, Ac in a triangle, Ac-3 strongly enlarged (Figs 8A, 9E). Palp: P-2 with strong ventrodistal protrusion consisting of a bluntly pointed medial hump and a convex lateral thickening; P-3 ventral margin concave; P-4 maximum H near proximoventral seta, sword seta between ventral setae (Figs 8 C–D, 9G). Female. Ac arranged in an obtuse angle (Fig. 10A). Palp: P-2 ventrodistal edge rounded; P-3 ventral margin straight or slightly concave; P-4 slender, slightly protruding near proximoventral seta (Fig. 10B).

Deutonymphs. Setae Dgl-1, Dgl-3, Dgl-4 and Lgl-2 longer than other dorsal setae; Preoc. and Postoc. without glandularia (Figs 10 D–F). Coxal field: covers about one half of ventral surface. Caudal margin of Cx-I convex. Excretory pore smooth; Vgl-1 fused to Vgl-2 (Fig. 10G). Genital field: 2 pairs of acetabula placed on fused anteriorly genital plates, each bearing 3 thin setae (Fig. 10H). Palps: P-2 with 1 proximal and 2 distal setae; P-3 with 2 distal setae; P-4 slightly convex, sword seta between ventral setae (Fig. 10I). Setation on I-L-5-6 similar to adults (Fig. 10J).

Measurements. Male (from CR22, in parentheses specimen from Russia, Tigrovaya River) - Idiosoma L/W 600/538 (560/476); coxal field: L 369 (336); Cx-III W 409 (383); Cx-I+II mL 138 (135), lL 263 (238); genital field L/W 129 (109)/ 157 (122), L Ac 1-3: 40-42 (37-42), 51-52 (39-40), 72 (50-51); ejaculatory complex L 127 (106).

Palp: Total L 317 (275), dL/H: P-1, 29/34 (29/36, 0.81); P-2, 77/55 (65/56); P-3, 75/48 (56/46); P-4, 97/29 (93/38); P-5, 39/15 (32/16); L P-2/P-4 ratio 0.79 (0.69). Gnathosoma vL 153 (127).

Legs: I-L-5 dL 218 (174), vL 142 (151), dL/vL ratio 1.53 (1.44), maximum H 59 (49), dL/maximum H 3.7 (4.45), S-1 L 105 (84), L/W ratio 8.5 (12), S-2 L 74 (73), L/W ratio 5.4 (9.1), distance S-1-2, 24 (16), L ratio S-1/2, 1.42 (1.15); I-L-6 dL 139 (120); central H 21 (20), dL/central H ratio 6.7 (6); dL I-L-5/6 ratio 1.57 (1.45).

Female (from Kedrovaya River, Russia, in parentheses specimen from Tigrovaya River) - Idiosoma L/W 765/730 (730/600); coxal field: L 405 (369); Cx-III W 402 (468); Cx-I+II mL 138 (139), lL 290 (264); genital field L/W 162 (142)/197 (174), genital plate L 137 (118); pregen W 65 (62); L Ac 1-3: 50 (47), 56 (50), 54 (51).

Palp: Total L 400 (368), dL/H: P-1, 38/51 (43/29); P-2, 89/76 (72/44); P-3, 116/56 (105/43); P-4, 124/35 (116/29); P-5, 33/19 (32/16); L P-2/P-4 ratio 0.72 (0.62). Gnathosoma vL 160 (147).

Legs: I-L-5 dL 248 (221), vL 170 (156), dL/vL ratio 1.46 (1.42), maximum H 79 (56), dL/maximum H 3.1 (3.9), S-1 L 124 (108), L/W ratio 12.4 (13.5), S-2 L 97 (82), L /W ratio 7.5 (8.2), distance S-1-2, 28 (24), L ratio S-1/2, 1.29 (1.32); I-L-6 dL 179 (156); central H 22 (20), dL/central H ratio 8.1 (7.8); dL I-L-5/6 ratio 1.36 (1.42).

Deutonymph - Idiosoma L/W 323/237); coxal field: L 173; Cx-III W 191; Cx-I+II mL 62, lL 119; genital plate L/W 49/28; L Ac 1-2: 19, 17.

Palp: Total L 165, dL/H: P-1, 18/18; P-2, 37/30; P-3, 43/22; P-4, 49/21; P-5, 18/10; L P-2/P-4 ratio 0.75. Gnathosoma vL 81.

Legs: I-L-5 dL 96, vL 76, dL/vL ratio 1.3, maximum H 31, dL/maximum H 1.5, S-1 L 47, L/W ratio 11.8, S-2 L 46, L/W ratio 9.2, distance S-1-2, 2.5, L ratio S-1/2, 1.02; I-L-6 dL 70; central H 16, dL/central H ratio 4.4; dL I-L-5/6 ratio 1.36.

Remarks.

Atractides constrictus was originally described by Sokolow (1934) from the Primory Territory in the Russian Far East as a ‘variety’ of Atractides nodipalpis . In the original description Sokolow (1934, 1940) gave particular weigt to the shape of P-4 in males: strongly thickened near proximoventral seta, basally strongly narrowed, ventral setae more closely approaching to each other. However, there is no reason to support the placement of this taxon as a subspecies of Atractides nodipalpis , as from the latter species, Atractides constrictus can easily be distinguished by the fused Vgl-1 and -2. Males examined from Korea show a general conformity with material from the Far East of Russia. Differences are found in a more enlarged Ac-3, a larger S-1/2 interspace and I-L-6 relatively longer compared to I-L-5 in specimens from Korea.

Distribution.

Far East of Russia (Primory Territory - Sokolow 1934). New for the fauna of Korea.