Limnesia (Limnesia) mongolica, Tuzovskij, 2021

Tuzovskij, Petr V., 2021, Description of a new water mite species of the genus Limnesia Koch, 1836 (Acari, Hydrachnidae: Limnesiidae) from Mongolia, Amurian Zoological Journal XIII (4), pp. 467-470 : 468-470

Limnesia (Limnesia) mongolica sp. nov.

(Figs. 1–8)

http://zoobank.org/NomenclaturalActs/ 5587A84A- 3A91-4E18-8A47-90120565E231

Type material. Holotype: male, slide 9946, Asia , West Mongolia , Durgun reservoir near a dam which has been constructed on Chonokharaikh River, depth 3.5 m, 21 August 2018, leg. A. Prokin. Paratype: one male, same locality and data as holotype .

Diagnosis. Seta Fch distinctly shorter than diameter of sclerite on which located; dorsum with two small transverse anterior sclerites bearing trichobothria Oi and comparatively large transverse unpaired posterior plate; genital field with three pairs of small acetabula, distance between ac.1 and ac.2 two to three times larger than any acetabulum, distance between ac.2 and ac.3 larger than diameter of any acetabulum; P-4 with two simple ventral setae near middle of segment; IV-Leg-6 with four to five ventral setae.

Figs. 1–5. Limnesia mongolica sp. n., male: 1 — seta Fch; 2 — left anterior dorsal platelet; 3 — posterior dorsal plate; 4 — coxal plates I–IV; 5 — genital field. Scale bars: 1 = 50 μm; 2, 3, 5 = 100 μm, 4 = 200 μm

Рис. 1–5. Limnesia mongolica sp. n., самец: 1 — щетинка Fch; 2 — Λевая переΑняя ΑорсаΛьная пΛастиночка, 3 — заΑняя ΑорсаΛьная пΛастинка; 4 — коксаΛьные пΛастинки I–IV; 5 — генитаΛьное поΛе. ШкаΛы: 1 = 50 μm; 2, 3, 5 = 100 μm, 4 = 200 μm

Description. Male. Integument soft and smooth. The number and position of idiosomal setae typical for the genus Limnesia ( Tuzovskij 1990) . Seta Fch (Fig. 1) thick, pointed and distinctly shorter than diameter of sclerite on which located. Dorsum with two small transverse anterior sclerites bearing trichobothria Oi (Fig. 2) and comparatively large transverse posterior plate (Fig. 3). Anterior coxal groups longer than wide, widely separated but connected by broad slightly sclerotized bridge, each with short posteromedial apodeme (Fig. 4). Posterior coxal groups wider than long, suture line between coxal plates III and IV incompletely obliterated medially. Setae and glandularia Pe separated and placed in medial portion of posterior coxal groups, glandularia Pe located close to medial end of suture line between coxal plates III and IV, seta Pe situated a little anteromedially to glandularia Pe on each side. Glandularium Hv free and located laterally between anterior and posterior coxal group on each side. Coxal plate IV triangular with a small broad-based extension near middle of medial margin.

Genital plate (Fig. 5) a little wider than long (L/W ratio 0.88–0.92), with 10–11 pairs short, thin setae and three pairs of small acetabula, distance between ac.1 and ac.2 two to three times larger than distance between ac.2 and ac.3. Posterior margin of genital plate slightly concave. Gonopore oval, about ½ genital plate length with pointed anterior and posterior ends.

Pedipalp slender (Fig. 6): P-1 short and without setae; P-2 large (L/H ratio 2.85–3.1), ventrally with a long projection inserted in the middle of segment and bearing short peg-like seta which is much shorter than the projection, dorsally with 9–11 short, thick subequal setae; P-3 relatively short (L/H ratio 1.55–1.60), with concave ventral margin, dorsally with six to seven short proximal setae and single dorsodistal one; P-4 very slen- der (L/H ratio 5.0–5.45), in the distal part strongly curved, longer than P-2 (length ratio P-4/P-2 1.45–1.50), maximum height in proximal quarter, with small ventral extension near middle of segment and bearing only two thin simple setae, proximal much longer than distal one; P-5 comparatively short, thin with slightly concave ventral margin.

Figs. 6–8. Limnesia mongolica sp. n., male: 6 — pedipalp; 7 — IV-Leg-4-6; 8 — leg claw. Scale bars: 6 = 100 μm; 7 = 200 μm, 8 = 50 μm

Рис. 6–8. Limnesia mongolica sp. n., самец: 6 – пе- ΑипаΛьпа, 7 – нога IV-4-6, 8 — коготок ног. ШкаΛы: 6 = 100 μm; 7 = 200 μm, 8 = 50 μm

Posterior two pairs of legs with swimming setae. III-Leg-5 with six to seven, IV-Leg-4 with two to three, IV-Leg-5 with six to nine long swimming setae, IV-Leg-6 with four to five relatively short ventral setae, terminal seta much longer than the ventral ones (Fig. 7). Leg claws (Fig. 8) with three unequal, pointed clawlets, central clawlet longest, dorsal clawl- et a little thinner and longer than ventral one. Claw lamella slightly developed with concave ventral margin.

Measurements (n = 2). Idiosoma L 1250– 1400; seta Fch L 25–30; anterior dorsal platelets L 30–35, W 48–60; posterior dorsal plate L 60–75, W 85–100; coxal plates III-IV L 410, W 480; genital plate L 200–210, W 210–225, genital acetabula (ac.1–ac.3) L: 30–37, 30–35, 30–37; cheliceral segments: base L 350–400, chela L 145–150; pedipalp segments (P-1–5) L/H: 60–65/87–100, 275–285/130–135, 175– 187/112–120, 410–425/75–85, 70–75/25–27; legs segments L: I-Leg-1–6: 100–105, 150– 175, 185–190, 200–210, 260–285, 225–235; II-Leg-1–6: 100–110, 200–210, 200–210, 300–310, 335–350, 210–285; III-Leg-1–6: 125–135, 175–210, 185–200, 285–290, 350– 365, 285–310; IV-Leg-1–6: 200–210, 200– 225, 250–255, 360–375, 410–425, 450–455; IV-Leg-6 terminal seta L 150–175.

Female. Unknown.

Differential diagnosis. The present species is similar to L. curvipalpis Tuzovskij, 1997 in the structure of pedipalps. Differences between the two species are found in the following characters (character states of L. curvipalpis given in parentheses, data from Tuzovskij 1997): male: seta Fch (Fig. 1) distinctly shorter than length of sclerite on which it located (seta Fch longer than diameter of sclerite on which it located, Fig. 9); genital acetabula small, distance between ac.1 and ac.2 two to three times larger than length of any acetabulum, distance between ac.2 and ac.3 equal or larger than diameter of any acetabulum, Fig. 5 (genital acetabula comparatively large, distance between ac.1 and ac.2 1.0–1.5 times larger than length of any acetabulum, distance between ac.2 and ac.3 much lesser than length of any acetabulum, Fig. 10); P-4 only with two simple ventral

Figs. 9–11. Limnesia curvipalpis Tuzovskij 1997 , male: 9 — seta Fch; 10 — genital field; 11 — pedipalp (after Tuzovskij 1997)

Рис. 9–11. Limnesia curvipalpis Tuzovskij 1997 , самец: 9 — щетинка Fch; 10 — генитаΛьное поΛе; 11 — пеΑипаΛьпа (по Тузовский 1997)

setae near middle of segment, Fig. 6 (P-4 with two simple ventral setae and one solenidion near middle of segment, Fig. 11); IV-Leg-6 with four to five ventral setae, Fig. 7 (IV-Leg-6 with six to eight ventral setae).

Etymology. The species is named after the name of the country ( Mongolia) where it was collected.

Habitat. Running and standing waters.

Distribution. Asia (West Mongolia).