Hygrobates tienshanensi, Pešić & Smit, 2021

Pešić, Vladimir & Smit, Harry, 2021, New records of the water mite genus Hygrobates Koch, 1877 from Kyrgyzstan (Acari, Hydrachnidia, Hygrobatidae), with the description of one new species, Ecologica Montenegrina 39, pp. 7-14 : 10-14

Hygrobates tienshanensi s sp. nov.

https://zoobank.org/ urn:lsid:zoobank.org:act:7A4D922D-1FFD-4645-A0D4-54ED31DB26C7

Figs. 3-4

Material examined — Holotype male ( RMNH), Kyrgyzstan, KR26 Kochkor region , along road Korchar-Balysky, rheocrenes + slow flowing stream, 42º16.391' N, 75º51.204' E, 1761 m asl., 15.viii.2013 dissected and slide mounted . Paratypes: 4/0/0, same place and data as the holotype ( RMNH); 1/0/0 , Kyrgyzstan, spring next to road, Ala-Archa National Park , 42°34.053 N, 74°28.959 E, alt. 2118 m asl, 9.viii.2013 ( RMNH) .

Diagnosis — Posterior margin of Cx-I+II medially equally rounded; number of Ac low (5-10), anterior margin of genital field (L/W ratio 0.99) with a small knob-shaped medial projection, posterior margin with a well-developed protrusion in the centre of indentation, extending beyond posterior genital plate margin.

Description — Integument finely striated; dorsal and ventrocaudal idiosoma without sclerotized muscle insertions. Coxae in three groups; posteromedial margin of Cx-I+II rounded ( Figs. 3A , 4A ); medial margin of Cx-IV almost straight. Genital field ( Figs. 3B , 4B ) rather slender, L/W ratio 0.99, with 5-10 pairs of Ac, anterior margin convex with a small knob-shaped medial projection, posterior margin with a well-developed protrusion in the centre of indentation, extending beyond posterior genital plate margin. Palp: ventral margin of P-2 proximally almost straight, distally protruding in a nose-shaped projection bearing denticles; P-3 distoventrally slightly protruding, covered by denticles; P-4 ventral margin slightly projecting near the insertion of two ventral setae, ventral setae located close together ( Figs. 3 C-D).

Measurements. Male (Holotype; in parentheses measurements of the paratypes) — Idiosoma: L 803 (581-911, n = 5), W 675 (472-761, n = 5); coxal field: L 397; mL of Cx-I + gnathosoma L 291; distance between lateralmost ends of Cx-II apodemes, 133; Cx-III W 503. Genital field L/W 169/171; gonopore L 85; number of Ac pairs: 6-7 (9-10 in one paratype specimen; 5-6 in juvenile paratype specimen). Ejaculatory complex ( Fig. 2C ) L 203.

Palp – total L 451; dL/H, dL/H ratio: P-1, 36/41, 0.88; P-2, 116/78, 1.48; P-3, 91/67, 1.35; P-4, 153/39[basal 38], 3.9 [4.1]; P-5, 55/22, 2.5; L ratio P-2/P-4, 0.76; P-3/P-4, 0.59.

Legs – dL of I-L-1-6: 66, 100, 113, 163, 172, 173. dL of IV-L-1-6: 144, 141, 197, 263, 275, 242.

Etymology — Named after the mountain range where the new species was found.

Discussion — The new species is similar to H. diversiporus Sokolov, 1927 , H. quanaticola Schwoerbel & Sepasgozarian, 1976 and H. zawali Pešić, 2015 in the equally rounded posteromedial margin of Cx-I+II and low number of acetabula (5–10, generally <12 pairs). Hygrobates diversiporus , a species originally described from a first order stream in the Caucasus ( Sokolow 1927) and later reported from Turkey (Erman et al. 2013) differs in the reverse heart-shaped genital field with an acute anterior angle and indented posterior margin having a broad, rounded median notch. H. quanaticola was originally described from a small channel which issues from a qanat near Rezayeh (= Urmia) in West Azerbaijan, Iran ( Schwoerbel & Sepasgozarian, 1976). Following the original description and re-examination of the type series by Pešić (2015), the male of H. quanaticola can be separated from H. tienshanensis sp. nov. in the shape of the genital field, with straight or weakly concave posterior margin (see Fig. 2C in Pešić 2015), and minor dimensions of palp segments (L P-2 <100, P-3 <80, P-4 <130 μm; data taken from the original description). H. zawali from Ohrid Lake, Macedonia (in parentheses measurements from Pešić 2015) differs in an ovoid male genital field (anterior margin without a medial projection, posterior margin irregularly convex), a shorter gonopore (52 μm) and the ventral setae on P-4 more distanced from each other (13–19 μm).

Habitat — The collecting sites are weakly flowing rheocrenes strongly exposed to sunshine and with substrata dominated by decomposing plants and organic detritus.

Figures

Figure 2. Hygrobates kirgizicus Sokolow, 1935, male: A – IV-L-5 and -6 (arrows indicate ventral setae, 2X); B – palp. Scale bars = 100 µm.

Figure 3. Hygrobates tienshanensis sp. nov., holotype male: A – idiosoma, ventral view; B – genital field; C-D – palp; E – I-leg. Scale bars = 100 µm.

Figure 4. Photographs of Hygrobates tienshanensis sp. nov., holotype male: A – idiosoma, ventral view; B – genital field; C – ejaculatory complex; D-E – palp.