Torrenticola (Torrenticola) vietnamica, Tuzovskij, Petr V., 2013

Tuzovskij, Petr V., 2013, New water mite species (Acari, Hydrachnidia) from Vietnam, Zootaxa 3700 (4), pp. 547-560 : 548-550

Torrenticola (Torrenticola) vietnamica , sp. n.

( Figs. 1–7 )

Holotype: female, slide 9518, Vietnam, Khanh Hoa Province, Khe (Khế) River near the inflow of Cai River (N 12°16.741’, E 108°54.669’), 0 2. 0 6. 2008 (leg. E.S. Gusev). The river has been dominated by pebbles and sand, depth 1.0 m, speed of current 0.8 m/s, pH 7.8.

Diagnosis. Female: dorsum with main dorsal shield, two pairs of anterior platelets and three pairs of long, very narrow platelets surrounding the lateral and caudal portions of the main shield; coxal shield large, covering about 8/ 10 of the ventral idiosoma; s etae Pi and Ci placed in zone secondary sclerotization, excretory pore lying in the soft integument; ventral side of P-4 concave, with two small tubercles near middle of the segment and four subequal setae.

Description. Female. Color dark brown. Idiosoma relatively wide and almost circular, frontal margin between setae Fch straight ( Fig. 1 ). Dorsum with main dorsal shield, two pairs of anterior platelets (medial and lateral) and three pairs of long, very narrow platelets surrounding the lateral and caudal portions of the main shield. All of these platelets are separated from dorsal shield. Anteromedial platelets narrow and shorter than anterolateral platelets, the latter widely rounded distally. Dorsal shield wide, covering about 4/5 of the dorsal surface (L/W ratio 1.05) and bearing one pair of setae (Sci). Glandularia Sci placed more than 100 µm from the lateral margins of the dorsal shield. Two muscle attachment sites with a fine sculpture are located posteriorly of setae Sci. Setae Fch thicker than other idiosomal setae. Setae Vi located on anteromedial platelets, setae Oi and Hi on anterolateral platelets; setae Fch, Fp, Ve, Oe, He, Li, Le, Si and four pairs of lyriform organs (i1–i2, i 4–i5) occupy peripheral position on soft integument, i3 on the first pair of narrow lateral platelets. Setae and glandularia Vi and Hi separated, others idiosomal setae and associated glandularia located close to each other. Eyes lenses small, subequal in size and located on a small protrusion of the frontal margin near setae Fp.

Coxal shield large, covering about 8/10 of the ventral idiosoma, capitular bay U–shaped ( Fig. 2 ). Suture line between coxae II+III 5.2 times shorter than the medial portion of coxae I. Genital field pentagonal in shape with six pairs of subequal acetabula which are covered by a pair of genital flaps. Genital field located posterior to the middle of ventral surface. Genital flaps rather wide (L/W ratio 2.1). Size of coxae IV moderately, their posteromedial margins situated closely but not fused to each other posterior of genital field, insertion of leg IV with small condyles; glandularia Pe (= E4 sensu Wiles 1997) located at the apex of coxal plate I. Glandularia Sce at the level of posterior end of the genital field. Setae Pi and Ci placed in the zone of secondary sclerotization, excretory pore lying in the soft integument.

Capitulum ( Fig. 3 ) with rather long rostrum, ventral margin curved; rostrum is twice times shorter than the basic part of the capitulum; anterior end of the rostrum curved dorsally.

Chelicera ( Fig. 4 ) thin, very long; claw short, crescent-shaped, with two rows of fine teeth on the concave side. Pedipalp ( Fig. 5 ) robust: P-1 short, with a single dorsodistal setae; P–2 thick, with straight ventral margin, with five dorsal approximately subequal setae, and one further seta laterally at the base of the ventrodistal conic projection; P–3 shorter than P–2, with straight ventral margin and with three dorsal setae (one proximal and two distal unequal setae), ventral side of P–3 with a projection and a single seta; P–4 with more or less equally convex dorsal side, one heavy seta and five thin setae on dorsodistal portion; ventral side of P-4 concave, with a two small tubercles near middle of segment and bearing four subequal setae; P–5 short with four unequal terminal spines.

Legs without swimming setae. Tarsi of legs II–IV gradually thickened to distal end, their ventral margin convex ( Fig. 6 ). Claws with long external and short internal clawlets, ventral margin of blade slightly concave ( Fig. 7 ).

Measurements (n=1). Idiosoma L 640, W 600; anteromedial platelets L 123, W 45; anterolateral platelets L 170, W 65; dorsal shield L 505, W 480; distance from glandularia Sci to lateral margin of dorsal shield 125; capitular bay L 165; L of median portion of coxae I 130 long, L of suture line of coxae II+ III 25; genital flap L 140, W 65; distance from posterior margin of genital field to excretory pore 155; basal segment of chelicera L 300, cheliceral claw L 66; pedipalpal segments (P-1–5) L: 36, 93, 60, 90, 18; lengths of leg segments: I—Leg-1–6: 35, 90, 85, 100, 115, 95; II—Leg-1–6: 35, 65, 78, 108, 125, 130; III—Leg-1–6: 65, 102, 80, 120, 155, 160; IV—Leg- 1–6: 115, 110, 125, 155, 185, 175.

Remarks. The new species is similar to Torrenticola semisuta (Halik, 1930) and T. tetrapora (Viets, 1935) . The setae Ci in both species lying in the soft integument, the insertion of leg IV is without a condyle (Wiles 1997). In contrast, in the female of T. vietnamica sp. n. setae Ci lying in the zone of secondary sclerotization and the insertion of leg IV is with a condyle ( Fig. 2 ). The insertion of leg IV of other representatives of this genus is without a condyle (Cook 1974, Goldschmidt 2007).

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

Habitat. Running waters.

Distribution. Asia ( Vietnam: Khanh Hoa Province).

Figures

FIGURES 1 – 2. Torrenticola vietnamica, sp. n. female: 1, dorsal view; 2, ventral view. Scale bar: 100 Μm.

FIGURES 3 – 7. Torrenticola vietnamica, sp. n. female: 3, capitulum, lateral view; 4, chelicera, lateral view; 5, pedipalp, lateral view; 6, genu, tibia and tarsus of leg IV; 7, claw of leg IV. Scale bars: 3 - 5, 7 = 50 Μm; 6 = 100 Μm.