Atractides (Atractides) magnisetus, Pešić & Smit, 2022

Pešić, Vladimir & Smit, Harry, 2022, Two new water mite species from Kyrgyzstan (Acari, Acariformes, Hydrachnidia), Ecologica Montenegrina 58, pp. 69-78 : 74-77

Atractides (Atractides) magnisetus sp. nov.

https://zoobank.org/ urn:lsid:zoobank.org:act:1BE5FF50-2ACC-4659-8EEC-F6DE838A9836

Figs. 5-6

Type material — Holotype ♂, Kyrgyzstan, KR27 River along the road to Som Kul Lake, 41º56.487' N, 75º35.272' E, 2428 m asl., 15.viii.2013, leg. Pešić & Smit, dissected and slide mounted ( RMNH).

Diagnosis (Female unknown) — Integument striated; excretory pore smooth; Vgl-1 not fused with Vgl-2. Anterior and posterior margins of genital plate with very shallow indentations, the caudal indentation filled with secondary sclerite, acetabula in a weakly curved line, maximum Ac diameter> 40 µm; ventrodistal margin od P-2 convexly protruding; P-4 sword seta strong near distoventral seta; I-L-5 S-1-2 separation ˂ 30 µm; I- L-6 dL/H ratio ˂ 6.0; L ratio I-L-5/6> 1.4.

Description. Male — Integument striated, muscle insertions unsclerotized; mediocaudal margin of Cx-I indented, apodemes of Cx-II in an obtuse angle with the idiosoma midline ( Figure 5 ). Anterior margin of genital field slightly concave, the caudal indentation filled with secondary sclerotization, acetabula in a curved line ( Fig. 5 ). Excretory pore smooth; Vgl-1 not fused with Vgl-2. Palp: P-2 ventral margin distally convexly protruding, P-3 stout, P-4 with maximum height near the proximoventral hair, sword seta strong and pinnate, located near distoventral seta ( Fig. 6A ). I-L-5 setae S-1 and S-2 separated, with obtuse tips, S-1 longish, S-2 slightly thicker, proximally enlarged; I-L-6 proximally thickened, slightly curved, from the centre to the claw furrow with parallel dorsal and ventral margins ( Fig. 6B ).

Measurements — Idiosoma L 634, W 527; maximum diameter Dgl-4, 25. Coxal shield L 384; Cx-III W 447; Cx-I+II mL 100, Cx-I+II lL 244. Genital field L/W 122/131, L Ac-1-3: 38-39, 44-45, 42- 40. Ejaculatory complex L 127.

Palp total L 334; dL/H, dL/H ratio: P-1, 39/38, 1.04; P-2, 80/63, 1.28; P-3, 66/52, 1.27; P-4, 110/44, 2.5; P-5, 39/14, 2.8; L ratio P-2/P-4 0.73. Chelicera total L 231.

Legs: I-L-5 dL 209, vL 134, dL/vL ratio 1.57, maximum H 59, dL/maximum H 3.53, S-1 L 98, L/W ratio 8.4, S-2 L 76, L/W ratio 5.4, distance S-1-2, 25, dL ratio S-1/2 1.3; I-L-6 dL 145, central H 25, dL/central H ratio 5.8; L I-L-5/6 ratio 1.44.

Female — Unknown.

Etymology — Named for its large sword seta of the palp.

Discussion — With regard to the shape of the palp (P-2 ventral margin distally convexly protruding, P-4 sword seta near distoventral seta) and genital field (anterior margin slightly concave, the caudal indentation filled with secondary sclerotization) the male of new species resembles Atractides arcuatus Thor, 1914 , a little known species originally described from a small mountain stream near Ordubad ( Azerbaijan) in the Caucasus ( Thor 1914) and later on reported from Armenia, Crimea, and Uzbekistan (see Sokolow 1940). The holotype of A. arcuatus was lost with the destruction of the Thor collection. In Gerecke’s (2003) revision of the Western Palaearctic species, the latter species was defined based on the proposed synonymy of A. dubius ( Sokolow, 1940) , a species which can be separated by the presence of a lineated integument ( Sokolow 1940). In the original description of A. arcuatus, Thor mentioned that ‘striae’ were dense, indicating that he probably observed a striated, rather than lineated integument as Gerecke (2003) explained in his revision. Based on the available information from the original description of A. arcuatus (see Gerecke 2003 for detailed discussion) the male of the latter species differs in the fusion of all coxae, I-L-5 with S-1 and -2 similar in shape and dimensions, I-L-6 slender and comparatively longer (I-L-5/6 ratio 1.31) and a lower dimensions of acetabula (about 30 µm). For a clear separation of the new species from A. arcuatus , a redescription of the latter species based on the material from the type locality is necessary.

In the key of Western Palaearctic species provided by Gerecke (2003), the new species is placed close to A. stankovici Pešić & Gerecke, 2010 and A. algeriensis (Lundblad, 1942) . Both species differ in a distinctly indented posterior margin of the male genital plate. Atractides stankovici (in parentheses data from Pešić et al. 2010), a crenophilous species known from the Balkans ( Pešić et al. 2010, 2021) differs in longer setae S-1 and -2, which are more separated (S-1/2> 100/90, interspace 27-39 µm), a slender I- L-6 (L/ H ratio 7.7-8.0) and length ratio I-L-5/6 ˂ 1.4. Atractides algeriensis , a rhitrobiontic species from Algeria, differs in considerably smaller Ac and genital field in the male (L/W <100/100, Ac diameter <25 µm; data from Gerecke 2003).

Distribution — Kyrgyzstan; only known from the type locality ( Fig. 7B ) in the Tien Shan Mountains at an elevation of about 2400 meters.

Figures

Figure 5. Atractides magnisetus sp. nov., ♂ holotype. Idiosoma, ventral view. Scale bar = 100 µm.

Figure 6. Atractides magnisetus sp. nov., ♂ holotype. A – palp, medial view; B – I-L-5 and -6. Scale bar = 100 µm.

Figure 7. Photographs of sampling sites: A – KR7 Chon-Kemin NP, upper part of stream near Ashu resort (locus typicus of Sperchon krameri sp. nov.); B – KR27 River along the road to to Som Kul Lake (locus typicus of Atractides magnisetus sp. nov.). Photos by V. Pešić.