Brachypoda rossica, Pešić, Vladimir & Semenchenko, Ksenia, 2014

Pešić, Vladimir & Semenchenko, Ksenia, 2014, Water mites of the genus Brachypoda Lebert, 1879 (Acari: Hydrachnidia: Aturidae) from South Korea and the Russian Far East, Zootaxa 3753 (4), pp. 335-346 : 342-345

Brachypoda rossica sp. n.

( Figs. 6A–C , 7A–F , 8A–E )

Material examined. Holotype: male (300-kas IBSS), RUSSIA: Amurskaya Province, Magdagachinsky District, Levaya Burinda River, 53°27.731'N, 125°07.808'E; depth 0,2– 1 m; substrates: coarse-grained sand, 21.vii.2006, Semenchenko & Sidorov. Paratypes: three females (308–310-kas– IBSS), same data as holotype.

Diagnosis. Male. Cauda slightly narrowed posteriorly, posterior margin of idiosoma almost straight; a distinct ridge extending anterolaterally from genital field but not reaching lateral idiosoma margins at level of IV-L insertions; distance Ac-2–3 about two diameters of Ac-1; IV-L-4 with short and pointed dorsodistal extension. Female. Anterior margin of Cx-I ending posterior to level of frontal idiosoma margin; number of swimming setae: II-L-5, 3, III-L-5, 3, IV-L-5, 3–4.

Male (holotype): Idiosoma L/W 554/416; dorsal shield L/W 501/409, idiosoma slightly tapering posteriorly, with rounded frontal and straight posterior margins ( Fig. 6A ); major portion of body sclerotized, except broad part of interscutal membrane in front; excretory pore and flanking glandularia on dorsal shield, near posterior margin. Tip of Cx-I not reaching frontal idiosoma margin; distance tip Cx-I – gonopore 488; gnathosomal bay L 112; distance between IV-L insertions 132; a distinct ridge extending anterolaterally from genital field ( Fig. 6B ); gonopore L/W 70/13, laterally flanked by the acetabula arranged in a weakly curved line, and numerous fine setae – most of these at anterior edge, 8–10 long hairs at the anterolateral margin of genital field, distance between Ac-2 and -3 about two diameters of Ac-1. Gnathosoma vL 67, L with apodemes 100; chelicera total L 113, basal segment L 78, claw L 35. Palp ( Fig. 6C ): total L 284, L/H, ratio L/H: P-1, 38/26, 1.45; P-2, 65/54, 1.2; P-3, 51/35, 1.46; P-4, 103/46, 2.2; P-5, 27/12, 2.25; P-1 with one dorsal seta; P-2 with anteroventral projection; P-3 ventral margin concave; P-4 proximally narrow, ventral margin convexly protruding, with one stout and one finer seta of equal length in the centre, dorsal surface with numerous solenidions. Legs: number of swimming setae: II-L-5, 4 (not exceeding tip of II-L-6, see Fig. 7A ), III-L-5, 3 (shorter than L of III-L-6, see Fig. 7B ); III-L-6 ventral and dorsal margins strongly diverging from base to tip ( Fig. 7B ); IV-L-4 distally strongly enlarged ( Fig. 7C ), here bearing four setae, two of these located ventrodistally, heavy and modified as shown in Fig. 7C , forming a short and pointed extension projecting over base of IV-L-5, with two heavy apical setae (one spatula-like and one slender with a denticulated margin), IV-L-4 L/H 108/51, ratio 2.1; IV-L-5 proximally narrow, ventral margin with scattered short setae, distal margin with five strong setae, three of these very long, whip-like, extending beyond tip of IV-L- 6, IV-L-5 L/H 181/65, ratio 2.7; IV-L-6 L/H 181/32, ratio 5.6; IV-L-6 slightly curved, ventrally with a line of longer setae. Claws of I–II-L ( Fig. 7D ) with well developed blade and 3 clawlets: dorsal and ventral clawlets short, central clawlet long, ventral margin of claw blade concave; claws of III-L ( Fig. 7E ) with 3 clawlets: ventral clawlet short, dorsal clawlet reduced to a small denticle, central clawlet long, ventral margin of claw blade convex; claws of IV-L modified as given in Fig. 7F , claws without dorsal clawlet and ventral clawlet reduced to a small denticle, anterior claw longer than posterior claw.

Female (paratypes): Idiosoma L/W 554–561/475–495; dorsal shield L/W 462–488/363–376 µm, excretory pore and flanking glandularia on transversal plate posterior to dorsal shield ( Fig. 8A ). Tip of Cx-I not extending to frontal idiosoma margin ( Fig. 8B ); L of ventral shield from tip Cx-I 442–443; gnathosomal bay L 115–118; distance between IV-L insertions 211–224. Genital plates L/W 76–84/35–41, transversal, each with 3 acetabula and 3–4 short, fine setae. Gnathosoma vL 80, L with apodemes 100; chelicera total L 121, basal segment L 86, claw L 35. Palp ( Fig. 8C ): total L 242–251, L/H, ratio L/H: P-1, 33–35/21–22, 1.6; P-2, 57–59/40–48, 1.2–1.4; P-3, 46–47/ 27–35, 1.3–1.7; P-4, 81–84/30–35, 2.4–2.7; P-5, 26–27/10–12, 2.2–2.6. Legs: number of swimming setae: II-L-5, 3, III-L-5, 3, IV-L-5, 3–4; IV-L unmodified, claws with 3 clawlets ( Figs. 8D, E ), IV-L-4 L/H 97–110/30–35, ratio 3.1–3.2; IV-L-5 L/H 119–135/23–32, ratio 4.2–5.2; IV-L-6 L/H 115–118/23–26, ratio 4.5–5.0.

Etymology. The species is named after the country where it was collected ( Russia).

Discussion. Tuzovskij (2004) introduced the new subgenus Eubrachypoda to accommodate B. japonensis Tuzovskij, 2004 , a species described from Lake Biwa in Japan. Due to the morphology of male genital field (set off from posterior margin), Eubrachypoda Tuzovskij, 2004, resembles Ocybrachypoda Cook, 1974 and Brachypoda s. str. Lebert, 1879. The later subgenus differs in the male in the posterior margin of Cx-IV on both sides forming a curved ridge extending from genital field to the level of IV-L insertions, and the acetabula arranged in a triangle. Ocybrachypoda Cook differs in IV-L-4 lacking a pronounced distal projection. The new species from the Far East of Russia closely resembles B. japonensis Tuzovskij, 2004 , but has partially developed ridges extending anterolaterally from genital field, not reaching lateral margins at level of IV-L insertions, suggesting that this character varies and cannot be used in subgeneric classification. Further differences with B. japonensis (in parentheses) include the following characters: cauda slightly narrowed posteriorly, with almost straight posterior margin (cauda strongly narrowed posteriorly, with rounded posterior margin); distance Ac-2–3 greater than width of Ac-1 (equal to width of Ac-1); dorsodistal extension on IV-L-4 shorter and pointed (longer and slender, fingershaped).

Habitat. A river with pebble and coarse-grained sand ( Fig. 9E ).

Distribution. Far East of Russia, known only from the locus typicus.

Figures

FIGURE 6 A – C. Brachypoda rossica sp. n., male: A = dorsal shield; B = idiosoma, ventral view; C = palp. Scale bars = 100 Μm (A – B), 25 Μm (C).

FIGURE 7 A – F. Brachypoda rossica sp. n., male: A = II-L- 5 and - 6; B = III-L- 5 and - 6; C = III-L- 3 – 6; D = claw of I-L; E = claw of III-L; F = claw of IV-L. Scale bars = 50 Μm (C), 25 Μm (A – B, D – F).

FIGURE 8 A – E. Brachypoda rossica sp. n., female: A = dorsal shield; B = idiosoma, ventral view; C = palp; D = IV-L- 4 – 6; E = claw of IV-L. Scale bars = 100 Μm (A – B, D), 25 Μm (C, E).

FIGURE 9 A – E. A – B Photographs of Brachypoda rubidata Kim & Chung, 1996, male: A = idiosoma, ventral view; B = idiosoma, dorsal view. C – E Photographs of sampling sites: C = CR 9 (stream in Naebyeansan NP, South Korea, locus typicus of Brachypoda milicaae sp. n.; D = CR 10 (pool near stream in Naebyeansan NP, South Korea, sampling site of Brachypoda rubidata Kim & Chung, 1996); E = Levaya Burinda River, Russia, locus typicus of Brachypoda sokolowi sp. n. and B. rossica sp. n. Photos. V. Pešić (Figs. A – D), K. Semenchenko (Fig. E).