Monatractides abei, Pesic, Vladimir, Semenchenko, Ksenia A. & Lee, Wonchoel, 2013

Pesic, Vladimir, Semenchenko, Ksenia A. & Lee, Wonchoel, 2013, Torrenticolid water mites from Korea and the Russian Far East, ZooKeys 299, pp. 21-48 : 39-43

Monatractides abei sp. n. Figs 12, 13, 11I

Type series.

Holotype male (NIBRIV0000268853), dissected and slide mounted, SOUTH KOREA, CR2 Seoul, Ui-dong stream, 37°39.554'N, 127°00.249'E, 114 m asl., 7.x.2012, Pešić & Choi. Paratypes: SOUTH KOREA, CR1 Seoul, Dobong stream, 37°41.262'N, 127°01.706'E, 19 m asl., 7.x.2012, Pešić & Choi, one female (NIBRIV0000268854), dissected and slide mounted; RUSSIA, Primory Territory, Partizansky District, Partizanskay River basin, Tigrovaya River, 43°11.401'N, 133°12.660'E; depth 30 cm below the sediment surface; substrate: cobbles, pebbles, sand; 12.vi.2010, Semenchenko & Sidorov, one female (497- kas–IBSS), dissected and slide mounted.

Diagnosis.

Lateral margins of dorsal shield nowhere subparallel; distal margins of P-3 with several pointed extensions; genital field in male with slightly protruding anteriolateral angles; medial suture line of Cx-II+III in female relatively long (L 90-105 μm).

Description.

General features. Lateral margins of dorsal shield nowhere subparallel (Fig. 12A, 11I); three pairs of knob-like protrusions on the lateral margin of gnathosomal bay; suture line of Cx-IV distinct, originating from lateral edge of genital field, laterally curved anteriorly; excretory pore away from the line of primary sclerotization, Vgl-2 posterior to excretory pore; ejaculatory complex (Fig. 12F): proximal chamber large, proximal horns reduced; P-2 equal in length, or only slightly shorter than P-4; distal margins of P-3 with several pointed extensions; ventral seta on P-4 relatively long and away from distal edge (Figs 12C-D). Male. Medial suture line of Cx-II+III moderately long, genital field with slightly protruding anteriolateral angles. Female: Similar to the male; the short postgenital area and caudal position of the excretory pore in the specimen from Korea are due to the obviously juvenile age (indicated by weak sclerotization and absence of eggs); medial suture line of Cx-II+III relatively long.

Measurements. Male: Idiosoma (ventral view: Fig. 12B) L 775, W 538; dorsal shield (Fig. 12A, 11I) L 663, W 488, ratio 1.36; dorsal plate L 606; shoulder plate L 191-194, W 75, ratio 2.5-2.6; frontal plate L 122-123, W 75, ratio 1.6; shoulder/frontal plate L ratio 1.6. Gnathosomal bay L 143, Cx-I total L 264, Cx-I mL 120, Cx-II+III mL 99; ratio Cx-I L/Cx-II+III mL 2.7; Cx-I mL/Cx-II+III mL 1.2. Genital field L/W 147/115, ratio 1.28; ejaculatory complex L 197; distance genital field-excretory pore 191, genital field-caudal idiosoma margin 264. Gnathosoma vL 152; chelicera total L 181; palp total L 199, dL: P-1, 23; P-2, 54; P-3, 40; P-4, 54; P-5, 28; P-2/P-4 ratio 1.0; dL of I-Leg-5-6 (Fig. 9G): 99, 97.

Female (from CR2, in parentheses specimen from Russia). Idiosoma (ventral view: Fig. 13B) L 725 (800), W 544 (612); dorsal shield (Fig. 13A) L 625 (680), W 488 (476), L/W ratio 1.28 (1.43); dorsal plate L 575 (620); shoulder plate L 203-206 (204), W 70-76 (74), L/W ratio 2.7-2.9 (2.76); frontal plate L 125-127 (114), W 69-70 (79), ratio 1.8 (1.43); shoulder/frontal plate L ratio 1.6 (1.79). Gnathosomal bay L 159 (132), Cx-I total L 283 (257), Cx-I mL 123 (118), Cx-II+III mL 90 (105); ratio Cx-I L/Cx-II+III mL 3.1 (2.45); Cx-I mL/Cx-II+III mL 1.4 (1.1). Genital field L/W 191 (145) /160 (112), ratio 1.19 (1.28); distance genital field-excretory pore (205), genital field-caudal idiosoma margin (277). Gnathosoma vL 162 (198); chelicera total L 202 (200); palp total L 209, dL: P-1, 28; P-2, 56 (54); P-3, 39 (40); P-4, 58 (54); P-5, 28 (19); P-2/P-4 ratio 0.97 (1.0); dL of I-Leg-4-6: 114 (103), 105 (100), 104 (94).

Etymology.

The species is named after Dr Hiroshi Abe in appreciation of his studies on water mites.

Remarks.

Monatractides abei sp. n. is apparently closely related to Monatractides madritensis (K. Viets, 1930), known from the Western Palaearctic, due to the presence of an elongated ventral seta on P-4 and the similar shape of the ejaculatory complex. Males of Monatractides madritensis differ in a more slender idiosoma with subparallel lateral margins of the dorsal shield, and a slender genital field with more protruding anterior margins of the genital flaps forming a more acute angle (see: Di Sabatino et al. 2010). Furthermore, in Monatractides abei nov. sp. the distal margins of P-3 bears several pointed extensions. The female of the new species can be identified on the basis of a relatively long medial suture line of Cx-II+III.

Enami (1940) stated that he identified Monatractides population from River Inôzava (Uzi region, Japan) as Torrenticola stadleri (syn. to Monatractides stadleri ), but he noted that his specimens differ from the later species in P-4 bearing an elongated ventral seta. Given the latter character and the shape of genital field in Enami’s specimens, with slightly protruding anteriolateral angles in male, resembling the female, suggest that these specimens are probably conspecific with Monatractides abei sp. n.

Habitat.

The specimens of Monatractides abei sp. n. was collected in two sandy/bouldary streams, shaded by riparian vegetation (Fig. 14A, D); the specimens from Russia were collected from interstitial waters.

Distribution.

South Korea, Far East of Russia (present study).