A new species of Promicrodispus (Acari: Microdispidae) from the Altai Republic, Russia Author Khaustov, Alexander A. X-Bio Institute, Tyumen State University, Tyumen, 6 Volodarskogo Str., 625003 Russia alex1973khaustov@gmail.com Author Shulaev, Nikita A. X-Bio Institute, Tyumen State University, Tyumen, 6 Volodarskogo Str., 625003 Russia text Acarological Studies 2024 2024-01-30 6 1 9 18 http://dx.doi.org/10.47121/acarolstud.1388820 journal article 10.47121/acarolstud.1388820 2667-5684 12192699 EA5DAD30-085C-4887-9142-C7F4CFAD1A80 Promicrodispus altaicus Khaustov sp. nov. ( Figures 1- 9 ) https://zoobank.org/ 706600E4-A22A-45DF-BE9D-69B6D49CB787 Figure 1 . Promicrodispus altaicus Khaustov sp. nov. , female: A. Dorsum of body; B. Venter of body. Legs omitted. Description Female (n=13). Length of idiosoma 225 (200–235), width of tergite C 135 (120–135). Gnathosoma ( Figs 7 , 8 ). Length of gnathosoma 24 (22–24), width 16 (14–16). Dorsal median apodeme absent. Cheliceral setae cha 14 (13–15) weakly barbed, pointed. Postpalpal setae flattened and blunt-tipped ( Fig. 8C ), situated anterolaterally to setae cha . Setae dFe 6 (4–6) slightly shorter than dGe 7 (6–7), both smooth and pointed. Subcapitular setae m 12 (11–13) smooth and pointed. Palpal tibiotarsus ventrally with sausage-like accessory setigenous structure ( ass ) and tiny (about 0.5) solenidion ω ( Fig. 7F ); tibial claw well-developed; palpal tibiotarsus with short spiniform seta (probably l” ) laterad tibial claw, short eupathid-like seta ( ϛ ) mesad tibial claw, and tiny projection probably of setal origin (?) posterolaterad ϛ ( Fig. 7B ). Pharyngeal pumps grouped together; pumps 1 and 3 small, bowshaped; pump 2 large, subrectangular and transversely striated ( Fig. 5D ). Figure 2 . Promicrodispus altaicus Khaustov sp. nov. , female: A. Right leg I, dorsal aspect; B. Right leg II, dorsal aspect. Figure 3 . Promicrodispus altaicus Khaustov sp. nov. , female: A. Right leg III, dorsal aspect; B. Right leg IV, dorsal aspect. Idiosomal dorsum ( Figs 1A , 4A , 5 A-C, 6A, B). Prodorsum separated from tergite C in slide-mounted specimens ( Fig. 5A ) and covered by tergite C in alive mites ( Fig. 6A ). Prodorsum with one pair of elongate stigmata with longitudinal slit-like openings leading from dorsal side to ventral ( Figs 5A , 7D ) and one pair of lateral spines ( Fig. 5A ). Posterior margin of tergite H with short and wide lobe. All dorsal shields with numerous very small round puncta ( Figs 5 A-C). Setae sc 2 short, smooth, needle-like, other dorsal setae sparsely barbed and pointed. Trichobothria with short stem, clavate, sparsely barbed, with rounded apex ( Fig. 6E ). Cupules ia on tergite D and ih on tergite H large, round; ia situated anterolaterally to bases of setae d ; ih situated anteromedially to bases of setae h2 . Tergite C with two pairs of porous areas situated laterally to bases of c1 and with one pair posteromedially to c1 ; tergite D with one pair of porous areas situated anterolaterally to setae d ; tergite EF with oval porous areas situated medially to bases of setae e ; tergite H with oval porous areas situated anteriorly to setae h1 . Tergites C, D and EF with weak longitudinal striae posteriorly. Lengths of dorsal setae: sc2 9 (7– 9), c1 29 (27–29), c2 37 (33–37), d 50 (48–52), e 57 (54– 60), f 53 (47–54), h1 47 (45–47), h2 62 (58–64). Distances between setae: sc2–sc2 31 (29–31), c1–c1 56 (53–56), с1– с2 21 (18–21), d–d 53 (50–53), e–f – 30 (28–30), f–f 37 (33– 37), h1–h1 38 (32–38), h1–h2 25 (24–26). Idiosomal venter ( Figs 1B , 4B , 5E, F , 6D, F , 7 A-C). Ventral plates with numerous very small puncta ( Figs 5E, F ). All ventral setae pointed; setae ps2 smooth; other ventral setae barbed; in some specimens setae 4a smooth; setae ps1 and ps2 contiguous ( Figs 5F , 6D ). Lateral plates with several oblique sclerotized lines laterally to legs III–IV ( Fig. 6C ). Ap1, appr and apsej well sclerotized and fused together; ap2 very thin and fused with appr; appo and ap4 well sclerotized and fused; ap3 very weakly sclerotized and poorly visible ( Fig. 5E ); ap5 absent. Posterior sternal plate with two pairs of porous areas just laterad ap4 and with two pairs of porous areas anteriad legs III. Posterior margin of posterior sternal plate weakly concave. Posterior margin of aggenital plate evenly rounded. Lengths of ventral setae: 1a 24 (24–25), 1b 19 (16–19), 2a 32 (28–32), 2b 37 (32–38), 3a 26 (26–30), 3b 22 (20–24), 3c 27 (23– 28), 4a 24 (24–26), 4b 47 (46–48), 4c 30 (28–31), ps1 29 (26–29), ps2 6 (5–6), ps3 44 (38–44). Legs ( Figs 2 , 3 , 9 ). Setation of legs as in generic diagnosis ( Khaustov 2017 ) except absence of seta s on tibiotarsus. Leg I ( Figs 2A , 9 A-D). Lengths of solenidia ω 1 13 (13), ω2 10 (9–10), φ1 8 (8–9), φ2 7 (6–7); φ1 weakly clavate, ω1 digitiform with attenuate tip, ω2 and φ2 baculiform. All setae of leg I (except eupathidia ( tc ), ( ft ) and p” ) sparsely barbed and pointed. Leg II ( Fig. 2B ). Solenidion ω 14 (12– 1) digitiform with attenuate tip, solenidion φ 4 (3–4) rodlike, situated in shallow depression. All setae on leg segments pointed and sparsely barbed; seta tc” usually with only several weak barbs in basal part. Leg III ( Fig. 3A ). Solenidion φ 2 (2) very short, situated in depression and hardly visible. All setae on leg segments pointed and sparsely barbed; seta tc” usually with only several weak barbs in basal part. Leg IV ( Fig. 3B ). Solenidion φ absent, but tibia with small pore-like depression instead of solenidion. Setae v” of tibia and pl” of tarsus smooth, other setae on leg segments sparsely barbed; seta v” of genu blunt-tipped, other leg setae pointed. Figure 4 . Phase-contrast micrographs of Promicrodispus altaicus Khaustov sp. nov. , female (holotype): A. General view dorsally; B. General view ventrally. Male and larva unknown. Type material. Holotype female, slide ZISP T-Mcd-4, Russia , Altai Republic , Turochaksky District , vicinity of Teletskoye Lake , bank of Tebenek River , 453 m a.s.l. , 01 October 2023 , in forest litter, 51°47'28.914" N 87°19'15.132" E , coll. A. O. Svinin ; paratypes : 12 females , same data. Type deposition. The holotype and one paratype female are deposited in the collection of ZINRAN; other paratypes are deposited in the collection of the TSUMZ . Differential diagnosis. The new species is closely resembles to P. pumilis in having very similar relative lengths of idiosomal setae and presence of one pair of cheliceral setae. The new species differs from P. pumilis in having setae ps2 (vs. setae ps2 absent in P. pumilis ) and in absence of seta s on tibiotarsus of leg I (vs. present in P. pumilis ). Etymology. The name of the new species altaicus refers to its geographical distribution in Altai Mountains.