Arrenurus (Megaluracarus) ussuriensis Sokolow 1931

Arrenurus (Megaluracarus) ussuriensis Sokolow, 1931

(Figs 13–16)

Material examined. GUGC, Slides No. JL-AR-2019072301–JL-AR-20190723025, Baicheng City, Jilin Province, P. R. China (4537′46″N, 12250′43″E; alt. 150 m), 23-VII-2019, Haitao Li leg .. 16/9/0.

Description. Male (n=16; Figures 13–14): Idiosoma L 730 (721–792), W 426 (426–502), L/W ratio 1.71 (1.57–1.71) (Fig. 13A). Anterior margin of idiosoma slightly concave (Fig. 13A). Dorsal furrow incomplete, W 387 (302–387); D 1 on small humps (Fig. 13A). D 3 and D 4 on well developed humps (Fig. 13A). Cx-I and Cx-II extending beyond anterior idiosoma margin; medial margin of Cx-IV equal in length with that of Cx-III (Fig. 13B). ACG medium L 181 (176–189); PCG medium L 218 (200–227); Gb–Cx-IV 314 (310–325); Gb–Gp 366 (354–375); Gb–Ep 462 (451–474); Ap enlarged at the Gp, extending to lateral margins of idiosoma, lateral parts narrower; Ap with four pairs of genital setae (Fig. 13B). L of palp segments: P-I 24 (21–25), P-II 53 (51-55), P-III 39 (39-49), P-IV 57 (51- 58), P-V 24 (24–27) (Fig. 13C); P-II without medial setae. L of leg segments: L of I-L-1–6: 47 (46–50), 76 (74–80), 94 (86–99), 104 (102–113), 113 (113–121), 155 (153–167) (Fig. 14A); L of II-L-1–6: 48 (47–51), 84 (81–86), 88 (85–96), 119 (104–122), 138 (116–138), 182 (169–184) (Fig. 14B); L of III-L-1–6: 51 (45–54), 94 (84–96), 96 (92–101), 124 (122–130), 140 (126–142), 164 (155–169) (Fig. 14C); L of IV-L-1–6: 83 (83–87), 125 (122–136), 136 (131–142), 185 (180–203), 125 (116–130), 156 (149–162) (Fig. 14D), IV-leg-4 with a short spur.

Female (n=9; Figures 15–16): Idiosoma approximately oval, L 881 (845–887), W 756 (734–776), L/W ratio 1.17 (1.14–1.17) (Fig. 15A); dorsal furrow complete, L 704 (689–716), W 582 (575–587); Dorsal humps absent (Fig. 15A). Cx-I and Cx-II extending beyond anterior margin of idiosoma; medial margin of Cx-IV equal in length with that of Cx-III (Fig. 15B); ACG medium L 184 (179–191), PCG medium L 219 (210–222), Gb–Gp: 290 (287– 298), Gb–Ep: 626 (623–654), Gb–Cx-IV: 264 (263–278) (Fig. 15B). Gp L 142 (138–149), W 144 (140–154) (Fig. 15B). Ap slightly bowed; Gp with two pairs of triangular sclerotized patches, anterior patch larger than posterior patch (Fig. 15B). L of palp segments: P-I 24 (23-27), P-II 51 (48-55), P-III 45 (44–49), P-IV 57 (55–62), P-V 27 (25–30); P-II with two medial setae (Fig. 15C); L of I-L-1–6: 45 (43–51), 91 (81–93), 90 (85–92), 115 (109–119), 116 (112–120), 138 (130–140) (Fig. 16A); L of II-L-1–6: 46 (46–52), 83 (73–85), 90 (90–107), 134 (130–135), 145 (141–147), 148 (142–152) (Fig. 16B); L of III-L-1–6: 59 (57–62), 101 (101–110), 102 (100–108), 134 (130–140), 139 (135–147), 137 (130–141) (Fig. 16C); L of IV-L-1–6: 81 (79–86), 139 (135–144), 137 (131–139), 179 (175– 185), 161 (157–168), 165 (160–171) (Fig. 16D).

Habitat. Still water.

Distribution. China (Jilin, Heilongjiang, Inner Mongolia); Russia (Sokolow 1931).

Remarks. This species was collected by Sokolow (1931) from the Ussuri River in the Soviet Union. The specimens from Baicheng City, Jilin Province show a general conformity with that from Russia. The species is firstly recorded for the Chinese fauna.

However, the two populations are slightly different in the following (Besseling 1968): (1) The D 3 on humps is very obvious in the Chinese specimen, while the D 3 on humps is very inconspicuous in the original description. The difference observed can be due to geographical variation.