Sperchon (Sperchon) orbipatella, Zhang, Xu & Jin, Dao-Chao, 2011

Zhang, Xu & Jin, Dao-Chao, 2011, New records of water mites of the family Sperchontidae Thor, 1900 from China (Acari, Hydrachnidia), with descriptions of two new species, ZooKeys 158, pp. 89-109 : 93-96

Sperchon (Sperchon) orbipatella sp. n. Figures 1121

Type series.

Holotype: Male, Xinjiang Uygur Autonomous Region, Urumqi city, Baiyanggou scenic area, an unnamed stream (43°40'53"N, 88°04'59"E), 18 August 1996, coll. Dao-Chao Jin. Paratypes: 46 males and 59 females, the same data as the holotype.

Diagnosis.

Cuticle covered with small papillae various in shape; excretory pore surrounded by a sclerotized ring; the second acetabulum near to the third but far away from the first one; P-II with a long ventro-distal projection and one thick seta at the base of the projection; third to fifth segments of leg I-IV with rather short plumose setae in longitudinal rows.

Description.

Male (n=3):Idiosoma oval in outline, 636 (602-783) in length, 533 (510-563) in width. Cuticle yellow-brown, covered with small, various shaped papillae (Fig. 13). A1 smooth, short and thick, other glandularia thin and longer. Cuticle without an extended dorsal and ventral plate. Glandularia and O2 encircled by small rounded platelets (Fig. 11, Fig. 12). Coxae in four groups, surface of coxae reticulated. ACG 162 (153-176) in length, close to each other but not fused, posterior apodeme weakly developed. E2 laterally between ACG and PCG. PCG 239 (228-257) in length. E4 close to anterior margin of CxIII. Distance between anterior end of ACG and posterior end of PCG 387 (364-412). Genital field between PCG with a small and rounded platelet in front. Genital valves not covering the genital acetabula, 170 (157-184) in length, 140 (132-165) in width. Pre- and postgenital sclerites not developed. Three pairs of small and rounded genital acetabula, the second acetabulum near to the third and far away from the first. V1 on very small sclerites and without accompanying glandularia. Excretory pore surrounded by a sclerotized ring and placed anterior to the line of V2 glands.

Infracapitulum with a relatively short and high rostrum, length 172 (165-184). Chelicera total length 223 (207-246), basal segment length 165 (155-183), claw length 58 (52-63), basal segment/claw length ratio 2.8 (2.8-3.0). Dorsal lengths of the palpal segments: P-I, 32 (25-34); P-II, 99 (80-107); P-III, 121 (113-134); P-IV, 163 (145-173); P-V, 37 (34-45). P-I short and without seta. P-II with a long ventro-distal projection bearing one thin seta and a thick peg-like seta at the base of the projection, the thick seta almost as long as the projection. Six setae on the dorsal side of the P-II, none of them plumose. The venter margin of P-III without setae, two setae on the dorsal side, one of which almost on middle and another one near to the distal end of the segment. P-IV venter with two subequal peg-like setae, well distanced from each other. Six thin setae on the dorsal side of P-IV, four of them on the terminal end of segment. Dorsal lengths of the first leg: I-L-1, 56 (47-69); I-L-2, 71 (58-86); I-L-3, 78 (62-88); I-L- 4, 144 (126-163); I-L-5, 145 (131-167); I-L-6, 143 (123-159). Dorsal lengths of the fourth leg: IV-L-1, 85 (76-93); IV-L-2, 107 (96-114); IV-L-3, 115 (108-127); IV-L-4, 238 (221-257); IV-L-5, 215 (197-226); IV-L-6, 205 (196-214). Third to fifth segments of leg I-IV with rather short plumose setae in longitudinal rows (Fig. 19). Claws with well protruded claw-blade and two clawlets, a long dorsal and a shorter ventral one (Fig. 15).

Female (n = 3):Similar to male except for the morphology of genital field (Fig. 21). Idiosoma 771 (725-947) in length, 645 (617-768) in width. ACG 199 (182-218) in length, PCG 272 (253-304) in length. Distance between anterior end of ACG and posterior end of PCG 448 (436-469). Genital field 209 (182-234) in length, 174 (163-181) in width. Infracapitulum length 210 (197-242). Chelicera total length 283 (262-307), basal segment length 212 (195-230), claw length 71 (67-77), basal segment/claw length ratio 3.0 (2.9-3.0). Dorsal lengths of the palpal segments: P-I, 37 (32-41); P-II, 122 (113-137); P-III, 155 (140-172); P-IV, 197 (178-217); P-V, 48 (40-54). Dorsal lengths of leg I: I-L-1, 67 (54-73); I-L-2, 100 (87-113); I-L-3, 128 (112-147); I-L-4, 217 (203-246); I-L-5, 197 (184-213); I-L-6, 183 (169-212). Dorsal lengths of leg IV: IV-L-1, 95 (87-106); IV-L-2, 148 (132-167); IV-L-3, 151 (137-173); IV-L-4, 299 (267-315); IV-L-5, 280 (262-301); IV-L-6, 227 (209-246).

Etymology.

The species is named after the shape of the three acetabula, “orbi-” Latin word, means rounded.

Remarks. All the species of the genus Sperchon have three pairs of acetabula, in most cases arranged almost equidistantly, usually the anterior two pairs of acetabula elongated while the posterior pair is somewhat rounded. However, in some species such as Sperchon prosperoides Tuzovskij, 1990 and Sperchon minutiporus Sokolow, 1934, the acetabula are small and rounded, and the second pair shifted near to the third one but far away from the first one.

The new species resembles to Sperchon prosperoides Tuzovskij, 1990, from Russia, from which it can been distinguished by the morphology of the palp and genital field ( Tuzovskij 2008). In Sperchon prosperoides , P-III bearing two thick setae on the ventral side and only half of the genital field is located between PCG, whereas in the new species, P-III is without setae on the ventral side and the genital field is located entirely between PCG.

Distribution.

China (Xinjiang Uygur Autonomous Region).