Mixobates amurensis, Tuzovskij, Petr V. & Semenchenko, Ksenia A., 2009

Tuzovskij, Petr V. & Semenchenko, Ksenia A., 2009, New water mites species (Acariformes: Hydrachnidia) from the Far East of Russia, Zootaxa 2241, pp. 1-21 : 14-17

Mixobates amurensis sp. n.

( Figs. 41–52 )

Type series. Holotype: male (131-kas– IBSS), Russia, Amurskaya Province, Skovorodinsky District, the Amur River basin, the Bolshoy Madalan River, N 54o03.433’; E 123o23.378’; depth 20–35 cm; substrates: stones, 16.07.2008. leg. D.V. Kotsuk. Paratypes: 4 males (132-135-kas– IBSS), 3 females (140-142-kas– IBSS), 1 male and 1 female (9528– IBIW), 2 females (9527– IBIW) same locality and date as holotype; 1 male (130-kas– IBSS), Russia, Amurskaya Province, Tyndinsky District, the Amur River basin, the Bolshoy Yankan River, N 54°15.646’; E 124°18.369’; depth 45 cm; substrates: stones, 17.07. 2008. leg. D.V. Kotsuk.

Description. Male. Integument membranous with a fine striation, without sclerotized muscle attachment plates dorsally and ventrocaudally ( Fig. 41 ). Setae Fch two times longer than their insertion sclerite ( Fig. 42 ). Coxae I–II posteriorly narrowed and with equally rounded posteriomedial margin ( Fig. 43 ). Suture line between coxae III–IV complete or almost complete. Glandularia Pe in the anterior part of the surface of coxae IV, posterior margin of coxae IV with distinctly projecting muscle apodemes. Genital field ( Fig. 44 ) enlarged, triangular; acetabula large, Ac. 3 larger than Ac. 1/Ac. 2; gonopore length generally about two thirds of genital field ( Fig. 43 ), but can occupy about half of plate length ( Fig. 44 ); 14–19 hairs on each side of genital field.

Chelicera basal segment ( Fig. 45 ) distally thickened, cheliceral stylet long, crescent-shaped.

Pedipalpal femur with straight ventral margin, ventrodistally without projection, bearing 5–9 pointed teeth ( Fig. 46 ). Genu of pedipalp with 6–8 teeth in the distal part of its ventral margin. Ventral margin of pedipalpal tibia slightly convex in the centre. Pedipalpal tarsus ( Fig. 47 ) gradually narrowed to the tip, with proximal solenidion, four thin setae and four claws, three of which curved, one dorsodistal straight.

Setae S-1/2 on I-L-5 rather strong (L 25 µm), subequal in size, with rounded tips ( Fig. 48 ).

Claws ( Fig. 49 ) with well developed claw blade, internal clawlet about half length of external clawlet.

Measurements, male (n=5). Length of body 450–630, width 383–490; length of seta Fch 27; length of length of coxae I–II 180–190, width 210–224; length of coxae III–IV 153–166, width 112–120; length of genital plate 108–132, width 121–131; length/width of genital acetabula (Ac. 1–3): 30–36/25–30, 36–42/24– 27, 40–42/25–30; length of basal segment of chelicera 112–150, length of cheliceral stylet 51–71; length of pedipalpal segments (P-1–5): 20–24, 64–69, 53–60, 94–96, 29–30; length of leg segments: I-L- 1–6 – 40 –44, 52–61, 75–84, 104–125, 131–138, 119–122; II-L- 1–6 – 41 –48, 54–66, 79–90, 126–138, 143–149, 127–132; III-L- 1–6 – 34 –54, 53–66, 71–96, 136–150, 156–168, 133–150; IV-L- 1–6 – 85 –108, 78–82, 115–119, 156– 164, 173–187, 136–163.

Female. Similar to male in the shape of coxae ( Fig. 50 ). Genital plate ( Fig. 51 ) L-shaped with well developed medial indentation. Acetabula large, covering a large part of plate surface, Ac. 2/Ac. 3 larger than Ac. 1; on each plate 13–15 hairs. Gonopore distinctly longer than genital plate, anterior and posterior genital sclerites almost subequal in size.

Palp ( Fig. 52 ) as in male, femur ventrodistally with 5–8, genu with 6–8 pointed teeth.

Measurements, female (n=4). Length of body 600–630; length of coxae I–II 180–218, width 250–260; length of coxae III–IV 180–210, width 180–217; length of genital plate 78–95, width 54–60; length of genital opening 102–120; length/width of genital acetabula (Ac. 1–3): 30–37/24–30, 30–41/21–27, 36–42/28–32; length of basal segment of chelicera 148–153, length of cheliceral stylet 60–72; length of pedipalpal segments (P-1–5): 24–30, 72–78, 64–72, 96–110, 33–37; length of leg segments: I-L- 1–6 – 42 –50, 60–66, 83–85, 125– 140, 138–149, 114–129; II-L- 1–6 – 41 –45, 60–66, 89–94, 135–149, 150–163, 114–143; III-L- 1–6 – 50 –54, 60–81, 90–102, 150–163, 168–183, 144–166; IV-L-1–6 – 102–108, 72–74, 120–136, 174–187, 190–207, 160–184.

Differential diagnosis. The new species is similar to the European species Mixobates caucasicus Tuzovskij, 1990 and to the Asian species M. uncatellus Tuzovskij, 2003 . Genital plate of male M. caucasicus with wide posteromedial projection, genital plate and genital opening in female subequal in length, pedipalpal femur with 2–4, genu with 3–5 teeth in both sexes ( Tuzovskij & Gerecke 2003); in contrast, in M. amurensis sp. n. genital plate of male without posteromedial projection, genital plate shorter than genital opening in female, pedipalpal femur with 5–9, genu with 6–8 teeth in both sexes. Genital field of male M. uncatellus with small acetabula, occupying less than one half of surface and 11 setae on each side, anterior genital sclerite almost twice wider than posterior one in female, each genital plate with 11–13 setae, pedipalpal genu with 2– 3 teeth in both sexes; in contrast, in M. amurensis sp. n. genital field of male with large acetabula, occupying more than one half surface and 14–19 setae on each side, pedipalpal genu with 5–9 teeth in both sexes, anterior and posterior genital sclerites almost subequal in size in female, each genital plate with 13–15 setae.

Etymology. The species is named after the Amur River, in basin of which it was collected.

Habitat. Running waters.

Distribution. Amurskaya Province, Far East of Russia.

Figures

FIGURES 41 – 43. Mixobates amurensis sp. n., male: 41, idiosoma, dorsal view; 42, seta Fch; 43, idiosoma, ventral view. Scale bars = 100 μm for Figs. 41, 43; 25 μm for Fig. 42.

FIGURES 44 – 49. Mixobates amurensis sp. n., male: 44, genital plate; 45, chelicera; 46, pedipalp, medial view; 47, pedipalpal tarsus; 48, tibia and tarsus of leg I; 49, claw. Scale bars = 50 μm for Figs. 44 – 46, 48; 25 μm for Figs. 47, 49.

FIGURES 50 – 52. Mixobates amurensis sp. n., female: 50, idiosoma, ventral view (part); 51, genital field; 52, pedipalp, medial view. Scale bars = 100 μm for Fig. 50; 50 μm for Figs. 51 – 52.