Atractides (Polymegapus) grigorievka, Pešić & Smit, 2018

Pešić, Vladimir & Smit, Harry, 2018, A checklist of the water mites of Central Asia with description of six new species (Acari, Hydrachnidia) from Kyrgyzstan, Acarologia 58 (1), pp. 165-185 : 173-175

Atractides (Polymegapus) grigorievka n. sp. ( Figure 3 )

Zoobank: F96801F6-F88E-4206-87B4-4ABA0296BD75

Type material — Holotype female ( RMNH), Kyrgyzstan, KR10 Grigorievka Gorge , rheocrenic spring, 42°46.585’N, 77°28.391’E, 1960 m asl., 11.vii.2013, leg. Pešić & Smit, dissected and slide mounted . Paratype: one female, Kyrgyzstan, KR23 Karakal region, rheohelocrenic spring, Žeti-Egaz village, 42°19.238’N, 78°51.017’E, 2094 m asl., 13.vii.2013, leg. Pešić & Smit, left palp and I-L dissected and slide mounted.

Diagnosis — Female (Male unknown). Integument striated; suture line Cx-III and –IV in its medial part directed posteriorly; P-3 ventral margin slightly convex with one (occasionally two) ventral seta; P-5 short; excretory pore smooth; acetabula in a slightly curved line; I-L-5 with S-1 ending in a bluntly pointed tip.

Description — Female — Integument dorsally striated, muscle insertions unsclerotized. Posterior margin of Cx-I weakly curved, with a subcuticular protrusion; suture line Cx-III and -IV in its medial part directed posteriorly ( Figure 3A ). Genital plates with narrow sclerite border, slightly indented between Ac-1/2 and Ac-2/3, acetabula in a slightly curved line ( Figure 3B ). Excretory pore smooth; Vgl-1 not fused to Vgl-2. P-3 ventral margin slightly convex, with one (occasionally two) ventral seta(e), inserted in the middle of segment; P-4 setae insertions dividing ventral margin into sectors 1:4:2, sword seta proximally from proximoventral seta; P-5 short ( Figures 3 C-D). I-L-5: S-1 with a blunt tip, more slender than S-2, S-2 pointed, strongly enlarged in the proximal part ( Fig. 3G ); I-L-6 stout, very thick at the base, distally tapering ( Figures 3 E-F).

Measurements — (holotype; in parentheses some measurements of paratype) — Idiosoma L 938 (1113), W 688 (925); coxal field: L 434; Cx-III W 553; Cx-I+II mL 134, lL 355; genital field L/W 223/224, genital plates L 144-145, pregenital sclerite W 122, maximum diameter Ac 1-3: 44, 31-38, 47-51.

Gnathosoma — palp total L 450; dL/H, dL/H ratio: P-1, 48/44, 1.1 (50/47, 1.06); P-2, 127/92, 1.38 (121/91, 1.34); P-3, 103/80, 1.29 (95/79, 1.2); P-4, 138/43, 3.2 (123/44, 2.82); P-5, 34/19, 1.83 (33/19, 1.75); L ratio P-2/P-4 0.92 (0.98). Chelicera total L 298.

Legs — I-L-5 dL 248 (232), vL 217 (186), dL/vL ratio 1.15 (1.25), maximum H 67 (72), dL/maximum H 3.7 (3.2), S-1 L 66, L/W ratio 5.3, S-2 L 70, L/W ratio 4.5, distance S-1-2 5.0, L ratio S-1/2 0.95; I-L-6 L 119 (108), maximum H 42 (41), L/maximum H ratio 2.8 (2.6); L ratio I-L-5/6, 2.1 (2.15).

Discussion — The new species is provisionally assigned to the subgenus Polymegapus K. Viets, 1926 , which was considered by Gerecke (2003) to be a monophyletic clade. The new species does not fit the diagnosis of the subgenus given by Gerecke et al. (2016) in the following features: 1) suture line Cx-III and –IV in its medial part directed posteriorly, 2) Cx-4 without triangular laterocaudal extensions of secondary sclerite, 3) I-L-5 with ventral margin shorter than dorsal margin, 4) P-5 short and less slender, and 5) excretory pore unsclerotized. The combination of the characters given under 1), 3) and 5) make the new species close to A. putihi Wiles, 1991 from SE Asia ( Wiles 1991, Pešić & Smit 2009, Smit & Pešić 2014). The latter species differs in genital plates, restricted to the level of the postgenital platelet, with the acetabula in a triangular arrangement, P-3 ventral margin slightly concave, without setae and IV-L-5 with 2 swimming setae. Probably A. grigorievka n. sp. represents an early derivative member with the typical palp and I-L not yet fully developed.

Etymology — Named after the canyon where the new species was found. The name is a noun in apposition.

Distribution — Kyrgyzstan, known from one rheocrenic ( Figure 10C ) and one rheohelocrenic spring ( Figure 10G ).

Figures

Figure 3 Atractides grigorievkan. sp., female holotype: A – idiosoma, ventral view; B – genital field; C – palp, lateral view; D – palp, medial view; E – I-Leg; F – I-L-5 and -6; G – sword setae (S-1 and -2) at the ventrodistal margin of I-L-5. Scale bars = 100 μm.

Figure 10 Photographs of sampling sites: A – KR3, Ala Archa NP, spring outlet (locus typicusof Atractides alaarchaensis n. sp.); B – KR32, stream near Son Kul lake (locus typicusof Atractides sonkulensisn. sp.); C – KR10, spring in Grigorievka canyon (locus typicusof Atractides grigorievkan. sp.); D – KR8, Chon-Kemin NP, upper part of stream near Ashu resort (locus typicusof Torrenticola kyrgyzican. sp.); E – KR15, river on the road to May Saz Pass (locus typicusof Wandesia albertii n. sp.); F – KR22, stream in Karakal region (locus typicusof Atractides manasi n. sp.); G – KR23, rheohelocrenic spring in Karakal region (sampling site of Atractides grigorievkan. sp.); H – KR31, river near Son Kol Lake (sampling site of Atractides sonkulensisn. sp.).