Limnesia (Limnesia) scharfi, Pešic & Smit, 2016

Pešic, V. & Smit, H., 2016, New records of water mites from Southeast Asia (Acari: Hydrachnidia) with the description of two new genera and 12 new species, Acarologia 56 (3), pp. 393-433 : 398-401

Limnesia (Limnesia) scharfi n. sp.

( Figures 3-4 )

Type material — Holotype male, dissected and slide mounted, Vietnam, 15-44-1 Bach MAE National Park, brook with a pool behind a natural barrier, 16°11’15.5"N, 107°50’54.7"E, alt. 1130 m a.s.l., water depth 0.2 m, substrate: leaves in a lentic bay; 2.v.2015 . Paratypes: 2/1/0, same data as holotype, one female dissected and slide mounted .

Diagnosis — Genital field with 2-3 small setae between Ac-1 and Ac-2; separation between Ac-1 and Ac-2 smaller than half the diameter of Ac-2; IV- L-6 with two thick ventral setae.

Description — General features – Colour yellowbrownish; integument finely striated. Dorsum posteriorly with a small, rounded platelet ( Figure 3A ). Cx-I medially separated, medial margins well developed, apodemes short. Cxgl-4 close to anterior margin of Cx-III. Genital plates with small setae, 2-3 of them located between Ac-1 and Ac-2 ( Figure 3B ); acetabula large, separation between Ac-1 and Ac-2 smaller than half the diameter of Ac-2. Excretory pore between associated glandularia.

Gnathosoma with long dorsodistal projections ( Figure 3E ); P-2 ventral margin with a rounded distal protrusion, bearing a spine-like seta, not on a basal tubercle; P-4 slender, in anterior half ventrally with two setae (proximal seta shorter than distal one), each associated with a very small tubercle, and more distally one small seta ( Figures 3 C-D).

Legs — Numbers of swimming setae: III-L-4, 6- 7; III-L-5, 9; IV-L-4, 4; IV-L-5, 5; IV-L-6 with two stout ventral setae, and a long subterminal seta ( Figures 3H , 4C ), L ratio seta/IV-L-6 1.05-1.06; claws of I-III-L with dorsal and ventral clawlets ( Figure 3G ).

Measurements — Male (holotype): Idiosoma L/W 995/697; posterior dorsal plate L/W 39/47, ratio 0.83; coxal field L/W 303/525, L Cx-I+II 162, Cx-III+IV 255; genital plate L/W 139/204, ratio 0.68, consisting of two flaps not fused at both ends; Ac-1 separated from Ac-2/3, separation half of diameter Ac-2; diameter Ac-1, 56-62; Ac-2, 48-49; Ac- 3, 45-47. Gnathosoma vL 108; chelicera total L 180, H 39, L/H ratio 4.7, L basal segment 123, claw 60, L ratio basal segment/claw ratio 2.1. Palp: total L 267, dL/H, dL/H ratio: P-1, 15/29, 0.5; P-2, 63/46, 1.37; P-3, 61/39, 1.58; P-4, 97/22, 4.5; P-5, 31/11, 2.9; L P-2/4 ratio 0.65. Legs: dL of I-L-2-6: 52, 63, 79, 95, 109; L/H I-L-6 ratio 3.4; dL of IV-L: 115, 80, 99, 134, 127, 96; IV-L-6 subterminal seta L 91.

Female (paratype, n–1): Idiosoma L/W 1194/975; posterior dorsal plate 39/47, ratio 0.83; coxal field L/W 370/700, Cx-I+II 180, Cx-III+IV 303; genital field L/W 175/131, individual genital plate L/W 159/63, ratio 2.6, consisting of two flaps not fused at both ends; Ac-1 separated from Ac-2/3, separation half of diameter Ac-2; diameter Ac-1, 56; Ac-2, 53-56; Ac-3, 45-50. Gnathosoma vL 145; chelicera total L 223, H 49, L/H ratio 4.6, L basal segment 155, claw 68, L ratio basal segment/claw ratio 2.3. Palp: total L 302, dL/H, dL/H ratio: P-1, 15/32, 0.48; P-2, 75/54, 1.4; P-3, 71/45, 1.6; P-4, 109/25, 4.44; P-5, 32/11, 2.9; L P-2/4 ratio 0.69. Legs: dL of I-L-2-6: 64, 69, 91, 108, 115; L/H I-L-6 ratio 3.7; dL of IV-L: 142, 102, 118, 169, 159, 128; IV-L-6 subterminal seta L 122.

Etymology — Named after Prof. Burkhard Scharf (Bremen, Germany), the collector of the mites described in this paper.

Remarks — The new species is similar to Limnesia vietnamensis Tuzovskij, 2013 , described by Tuzovskij (2013a) on the basis of one female and one deutonymph from Vietnam. Both species have P-2 with a ventrodistal protrusion with a peg-like seta and a dorsum with the small posterior transverse platelet. Female L. vietnamensis differs from the new species in 1) separation between Ac-1 and Ac-2 considerably larger than half of diameter Ac-2, 2) peglike seta of P-2 longer and more slender, and (3) IV-L-6 with four short thick ventral setae (Tuzovskij 2013).

Distribution — Vietnam; known only from the locus typicus ( Figure 25C ).

Limnesia (Limnesia) cf. rimiformis Jin, 1997 ( Figure 5 )

Material examined — Vietnam, 15-43-1, ca. 35 km W of Dà Nang, rice field, recently flooded, 16°16’02.2"N, 107°51’52.2"E, alt. 10 m a.s.l., water depth 0.1 m, substrate: loam covered by detritus, 1.v.2015, 1/0/0 (mounted) .

Description — Male: Colour yellow-brownish; integument finely striated. Dorsum posteriorly with a small, rounded platelet ( Figure 5A ). Cx-I medially separated, medial margins well developed, apodemes short. Cxgl-4 separated from anterior and medial margin of Cx-III. Genital plate rounded, without anterior or posterior indentations, posterior margin convexly protruding; 5-10 small setae on genital plates, 3 of these located between Ac- 1 and Ac-2 ( Figure 5B ); Ac-2 and -3 closer to each other than Ac-1 and -2, separation Ac-1-2 as large as diameter of Ac-2; ejaculatory complex reduced to a spherical chamber with a pair of arms ( Figure 5I ). Excretory pore between associated glandularia.

Gnathosoma with slightly convex ventral margin and a long dorsodistal projections ( Figure 5E ); P-2 ventral margin slightly bulging, peg-like seta not on a tubercle, inserted in the distal half; P-3 dorsally with three long setae; P- 4 in anterior half ventrally with two long setae (proximal seta shorter than distal one), each associated with a tubercle, and more distally one small seta ( Figures 5 C-D).

Legs — Numbers of swimming setae: III-L-4, 6; III-L-5, 8; IV-L-4, 6; IV-L-5, 6; IV-L-6 bearing four stout ventral setae, and a long subterminal seta ( Figure 5K ), L ratio seta/IV-L-6; claws of I-III-L with dorsal and ventral clawlets ( Figure 5G ).

Measurements — Idiosoma L/W 756/644; posterior dorsal plate L/W 72/74, ratio 0.97; coxal field L/W 328/553; genital plate L/W 159/169, ratio 0.94; diameter Ac-1, 38-43; Ac-2, 31-33; Ac-3, 38-39. Gnathosoma vL 137; chelicera total L 217, claw L 69, basal segment L 159, L basal segment/claw ratio 2.3. Palp: total L 320, dL/H, dL/H ratio: P-1, 19/42, 0.45; P-2, 92/62, 1.5; P-3, 69/54, 1.3; P-4, 106/32, 3.3; P-5, 34/15, 2.2; dL P-2/4 ratio 0.87. Legs: dL of I-L- 2-6: 53, 59, 69, 87, 100, 117; dL/H I-L-6 ratio 3.3; dL of IV-L: 117, 85, 111, 155, 155, 151; IV-L-6 subterminal seta L 79.

Remarks — Due to the similar shape of palp (peg-like ventral seta of P-2 inserted directly on the slightly convex segment surface) and genital field (genital plate rounded, without anterior and posterior indentations, posterior margin convexly protruding, separation between Ac-1 and Ac-2 less than half of diameter Ac-2) the single specimen from Vietnam shows general agreement with Limnesia rimiformis Jin, 1997 from China ( Jin 1997). Following the original description of the latter species it differs by the dorsum without posterior platelet(s), a character lacking in descriptions of all other species of the genus from China (see Jin 1997). As it is possible that this character has been overlooked, we keep our specimen tentatively un- der L. rimiformis .

Figures

FIGURE 3: Limnesia (Limnesia) scharfi n. sp., male, Bach MAE National Park, Vietnam: A – idiosoma, dorsal view; B – coxal and genital field; C – palp, medial view (P-5 lacking); D – palp, lateral view; E – gnathosoma; F – chelicera; G – I-L-5 and -6; H – IV-L. Scale bars – 100 µm.

FIGURE 4: Limnesia (Limnesia) scharfi n. sp., female, Bach MAE National Park, Vietnam: A – coxal and genital field; B – palp; C – IV-L-6. Scale bars – 100 µm.

FIGURE 25: Photoghraphs of sampling sites: A – Laos, Kauangxi Waterfall (locus typicus of Monatractides laosensis n. sp., Hexaxonopsis laosensis n. sp., Sinaxonopsis laosensis n. sp. and Africasia purpurea n. sp.); B – Laos, Kouangxi Waterfall, pond behind artifical barrier (sampling site of Hygrobates hamatus K. Viets, 1935, H. henni Wiles, 2004 and locus typicus of Forelia gereckei n. sp.); C – Vietnam, Bach MAE National Park, brook with a pool (sampling site of Monatarctides sp. and locus typicus of Limnesia scharfi n. sp., Schwoerbelia pioniformis n. sp. and Arrenurus contortus n. sp.; D – Cambodia, moat around the main Angkor temple (locus typicus of Hexaxonopsis

FIGURE 5: Limnesia (Limnesia) cf. rimiformis Jin, 1997, male, rice field W of Dà Nang, Vietnam: A – idiosoma, dorsal view; B – coxal and genital field; C – palp, lateral view; D – palp, medial view; E – gnathosoma; F – I-L-5 and -6; G – III-L claw; H – chelicera; I – ejaculatory complex; K – IV-L-6. Scale bars – 100 µm.