Description of Chaetocladius (Chaetocladius) spiridonovi sp. nov. from the Russian Arctic Region (Diptera, Chironomidae) Author Krasheninnikov, Andrey B. 0000-0001-9876-1008 Institute of Biological Problems of the North Far East Branch of the Russian Academy of Sciences, Portovaya St. 18, 685000 Magadan, Russia. & krasheninnikov 2005 @ yandex. ru; https: // orcid. org / 0000 - 0001 - 9876 - 1008 krasheninnikov2005@yandex.ru Author Tanadbaeva, Dana A. 0000-0002-1854-3666 Laboratory of Ecology and Evolutionary Biology of Aquatic Organisms, Institute of the World Ocean, Far Eastern Federal University, Suhanova St. 8, 690950 Vladivostok, Russia. & teda 2611 @ gmail. com; https: // orcid. org / 0000 - 0002 - 1854 - 3666 teda2611@gmail.com Author Vshivkova, Kristina A. 0000-0002-2472-7429 Institute of Biological Problems of the North Far East Branch of the Russian Academy of Sciences, Portovaya St. 18, 685000 Magadan, Russia. & kaktusovak @ inbox. ru; https: // orcid. org / 0000 - 0002 - 2472 - 7429 kaktusovak@inbox.ru text Zootaxa 2022 2022-03-18 5116 2 292 298 journal article 20175 10.11646/zootaxa.5116.2.6 79701af6-c816-4584-87fe-67e31915c5fc 1175-5326 6367383 81120B67-D46B-4E51-93A1-5C017B145D19 Chaetocladius spiridonovi sp. nov. , Krasheninnikov urn:lsid:zoobank.org:act: FCCC4401-F3AD-4635-80B8-E3FBF42F3642 ( Figs. 1–5 ) Chaetocladius sp. 7 ES| available from: http://boldsystems.org/index.php/Public_RecordView?processid=ATNA483-10 Material examined. Holotype , ♂ , RUSSIA : Nenets Autonomous Okrug , Yugorsky Peninsula , cape Beliy Nos , lake, N 69,607361º E 60,211639º 6 m , 08.viii.2015 , leg. Andrey B. Krasheninnikov ( CCK ). Paratypes , 5 ♂ , same locality and data as for holotype ; 1 ♂ , RUSSIA : Nenets Autonomous Okrug, Vaygach Island, Lyamchin Peninsula, neighborhood of Cape Bolshoi Lyamchin Nose, stream, N 69,857806º E 59,147222º 4 m , 07.viii.2015 , leg. Andrey B. Krasheninnikov (CCK). Derivatio nominis. The species is named ‘ spiridonovi ’ in honor of the Russian marine biologist Vasiliy A. Spiridonov ( 07.04.1957 – 17.12.2020 ), who devoted many years of his life in studying and preserving the region delimited by the polar latitudes. FIGURES 1–5. Male adult of of Chaetocladius spiridonovi sp. nov . , 1-2, hypopygium in dorsal and ventral view; 3, anal point in lateral view; 4, gonostylus; 5, tibial spur of hind tibia. Description. Adult male (n = 3) Total length 2.9–3.1 mm , and abdomen 2.1–2.2 mm . Wing length 1.8–1.9 mm . Ratio total length/wing length 1.60–1.65. Head, thorax, abdomen and legs light brown. Head. Eye bare, reniform. Temporal setae 8–10 including inner and outer verticals and 1–2 postorbitals.Antenna with partly reduced plume, AR 0.74–0.77. Clypeus with 8–9 setae. Lengths (in μm) of palpomeres): 24–31; 27–43; 122–125; 86–106; 122–149. Thorax. Lateral antepronotals 4–7; dorsocentrals 10–12; acrostichals 13 (begin close to antepronotum), prealars 4–5. Scutellum with 5–9 setae. Wing. Brachiolum bare. Membrane with strong punctation under X400 magnification. R with 13–16, R 1 with 3–6, R 4+5 with 0–8 setae; other veins bare. Anal lobe slightly truncated. Costa extending to apex of R 4+5 on 15–30 μm. R 4+5 ending distal to end of M 3+4 . R 2+3 weak. Squama with 3–5 setae. Legs. Fore tibia with 59 μm long spur; mid tibia with 31 μm and 24 μm long spurs; hind tibia ( Fig. 5 ) with 47 μm and 24 μm long spurs. Hind tibial comb consists of 17 setae. Pseudospurs present on: ta 1 -ta 2 of P 2 and ta 1 -ta 3 of P 2 . Pulvilli reduced, empodium present. Length (in μm) and proportions of legs as in Table 1 . TABLE 1. Male adult of Chaetocladius spiridonovi sp. nov. Length (in μm) and proportions of legs (n = 3).

fe	ti	ta1	ta2	ta3	ta4	ta 5	LR	BV	SV	BR
P 1	796– 889	920– 1014	515– 608	328– 343	172– 250	140– 156	109– 125	0,55– 0,61	3,00– 3,04	3,22– 3,36	2,0–2,2
P2	780– 858	874– 920	343– 406	234	156	94	94	0,39– 0,45	3,46– 3,66	4,38– 4,82	2,75
P3	889– 936	920– 1045	530– 593	281– 312	203– 234	109– 140	94–109	0,57– 0,58	3,19– 3,58	3,32– 3,41	2,2–2,8

Hypopygium ( Figs 1–4 ). Tergite IX with 22–26 setae located on each side of the dorsal midline and the basal part of anal point. Anal point 120 µm long, reaching almost apex of gonocoxite, basal part rectangular, protruding dorsally into a characteristic dorsal hump which is clearly visible in lateral view ( Fig. 3 ), basal part with lateral setae. Laterosternite IX with 4–7 setae. Virga 86 μm long consisting of 2 long spines. Transverse sternapodeme 110–125 μm long, phallapodeme 98–102 μm long. Gonocoxite 239–255 μm long. Superior volsella absent. Inferior volsella (IVo) sub-rectangular to large lobe shaped, located on distal part of gonocoxite; dorsal side with 15-20 short setae; posterior margin with characteristic undulation. Gonostylus 71–78 μm long, massively globular with rounded posterior margin; crista dorsalis low, located distally; megaseta 8–12 μm long, well-developed. HR 3.25–3.39. Female, pupa and larva. Unknown. Diagnostic characters. The new species is similar to C. crassisaetosus , C. elenae , C. variabilis , C. eugenyii but differs from them in having: anal point very long, with dorsal projection and ending almost at apex of gonocoxite; virga composed of 2 pointed long spines; IVo nearly sub-rectangular, inner and caudal margins with undulation, dorsal side with about 15-20 short setae; gonostylus massively globular, with rounded posterior margin, crista dorsalis low, located distally. Distribution The new species is known from its type-locality at the Yugorsky Peninsula, Russia , from the Vaygach Island, Russia and Vidjedalsbekken (upper), Dovre, Rondane nationalpark, Norway ( N 61,9717º E 9,83606º 1280 m , 31.viii.2008 , leg. T. Hoffstad, sequence ID in BOLD: ATNA483-10.COI-5P) ( Ekrem et al., 2018 ).