Geologicheskii Vestnik

For the first time, remains of extremely rare fossil crustaceans – cyclidans – have been discovered in the Cisuralian (Lower Permian) reef of Toratau. The specimen in question is an internal mold of a carapace in poor preservation, with a partially eroded surface. However, the general morphology, as well as a preserved portion of the marginal rim, allow this cyclidan to be identified as Skuinocyclus sp. Previously, representatives of Skuinocyclus were known exclusively from the Shakhtau reef.

Crustaceans, cyclidans, Skuinocyclus, Permian, Asselian, Sakmarian, Urals, Toratau

• Ufa Automobile Atlas. (2020) The Republic of Bashkortostan. Ufa: Publishing Center "OOO PKK ZetaPrint. 48 p. (In Russian).
• Gorozhanin V.M., Gorozhanina E.N. (2023) Tectonic structure and stages of geological development of the Sterlitamak Shikhans. Geologicheskii vestnik. 3, 98–129. DOI: 10.31084/2619-0087/2023-3-9 (In Russian).
• Gorozhanina E.N., Gorozhanin V.M., Sagdeeva N.S. (2023) Lithofacial features of the lower permian limestones of the Sterlitamak shikhans. Geologicheskii vestnik. 2, 4–25. DOI: 10.31084/2619-0087/2023-2-1 (In Russian).
• Kramarenko N.N. (1961) A representative of Cyclidae (Crustacea) from the Lower Permian of the Urals. Paleontologicheskiy Zhurnal. 2, 86–89. (In Russian).
• Mychko E.V. (2022a) Amazing Cyclidans — the Witnesses of the Great Extinction: Part 1. Priroda. 9, 12–23. DOI: 10.7868/S0032874X22090022 (In Russian).
• Mychko E.V. (2022b) Amazing Cyclidans — the Witnesses of the Great Extinction: Part 2. Priroda. 10, 26–35. DOI: 10.7868/S0032874X22100039 (In Russian).
• Mychko E.V., Mazaev A.V., Davydov A.E., Gibshman N.B., Sakhnenko K.V., Alekseev A.S. (2019) Akkermanovka-Khabarnoe – new Early Carboniferous Lagerstätt in Russia (South Urals) Bulletin of Moscow Society of Naturalists. Geological Series. 94 (3), 46–55. (In Russian).
• Register of Specially Protected Natural Territories of the Republic of Bashkortostan (2010). Izd. 2-e, pererab. Ufa: Izdatel’skiy centr «MediaPrint». 414 p. (In Russian).
• Chernyshev B.I. (1933) Artchropods from the Urals and other places of the USSR, 7. Representatives of the genus Cyclus from the Lower Carboniferous of the Urals and Turkestan: Materialy Tsentralnogo Nauchnoissledovatelskogo Geologo-Razvedochnogo Instituta, Sbornik 1, Paleontologia i Stratigrafia. P. 20–21. (In Russian with English summary).
• Shamov D.F. (1984) Permian section of Shakhtau and Tratau solitary mounts. 27th International Geological Congress. Guidebook for the South Urals. Excursion 047. Moscow: Nauka Publ. P. 22–25. (In Russian).
• Clark N.D.L., Hoare G., Murdoch M.P. (2026) A new occurrence of Britanniclus (Pancrustacea, Multicrustacea) from Blairskaith Quarry, East Dunbartonshire, and a redescription of Cyclidae from Trearne, North Ayrshire, from the Lower Limestone Formation (Brigantian, Visean, Carboniferous) of Scotland. Scottish Journal of Geology. 62 (1). DOI: 10.1144/sjg2025-016
• Dernov V.S. (2022) The first record of Cyclida (Pancrustacea, Multicrustacea) in the Carboniferous of the Donets Basin, Ukraine. Collection of Scientific Works of the Institute of Geological Sciences of NAS of Ukraine. 15 (1), 78–85. https://doi.org/10.30836/igs.2522-9753.2022.267079
• Dzik J. (2008) Gill structure and relationships of the Triassic cycloid crustaceans. Journal of Morphology. 269, 1501–1519. DOI: 10.1002/jmor.10663 PMID: 18690662
• Feldmann R.M., & Schweitzer C.E. (2019) The enigmatic Cyclida (Pancrustacea): morphological terminology and family-level classification. Journal of Crustacean Biology. 39, 617–633. DOI: 10.1093/jcbiol/ruz053
• Hopwood A.T. (1925) On the family Cyclidae Packard. Geological Magazine. 62 (7), 289–309. DOI: 10.1017/S0016756800105606
• Mychko E.V. (2025) The first Triassic cyclidan (Multicrustacea: Cyclida) from Russia. Historical Biology. P. 1–19. DOI: 10.1080/08912963.2025.2592987
• Mychko E.V., Feldmann R.M., Schweitzer C.E., Alekseev A.S. (2019) New genus of Cyclida (Crustacea) from Lower Carboniferous (Mississippian, Viséan) of Russia and England and new species from Viséan of Russia. Neues Jahrbuch für Geologie und Paläontologie – Abhandlungen. 294 (1), 81–90. DOI: 10.1127/njgpa/2019/0847
• Mychko E.V., Alekseev A.S. (2018) Two new genera of Cyclida (Crustacea: Maxillopoda: Branchiura) from the Cisuralian (Lower Permian) of Southern Urals. Neues Jahrbuch für Geologie und Paläontologie – Abhandlungen. 289 (1), 23–34. DOI: 10.1127/njgpa/2018/0747
• Mychko E.V., Alekseev A.S., Schweitzer C.E. (2025) New Carboniferous and Permian cyclidans (Multicrustacea: Cyclida) from the Urals (Russia): unpublished collection of B.I. Chernyshev at the CNIGR museum in St. Petersburg. Journal of Paleontology. 99 (3), 567–581. DOI: 10.1017/jpa.2024.85
• Mychko E.V., Alekseev A.S., Zaytseva E.L., Schweitzer C.E., Feldmann R.M. (2022) New finding of Cyclida (Crustacea) from Mississippian and not-cyclidan from Permian of Russia. Neues Jahrbuch für Geologie und Paläontologie – Abhandlungen. 305 (1), 75–85. DOI: 10.1127/njgpa/2022/1077
• Pieroni V. (2024) The first Cyclida from the Triassic of Ital. Swiss Journal of Palaeontology. 143 (1). No. 9. DOI: 10.1186/s13358-024-00306-9
• Schweitzer C.E., Mychko E.V., Lehnert M.S. (2025) North American midcontinental cyclidans (Pancrustacea: Multicrustacea: Cyclida) revisited. Journal of Crustacean Biology. 45 (3). DOI: 10.1093/jcbiol/ruaf045
• Schweitzer C.E., Mychko E.V., & Feldmann R.M. (2020) Revision of Cyclida (Pancrustacea, Multicrustacea), with five new genera: Neues Jahrbuch für Geologie und Paläontologie. Abhandlungen. 296 (3), 245–303. DOI: 10.1127/njgpa/2020/0905
• Tang H.Y., Mychko E.V., Feldmann R.M., Schweitzer C.E., Shaari H., Sone M. (2021) Malayacyclus gen. nov., the first Southeast Asian Cyclida (Crustacea) from the Early Carboniferous of Terengganu, Malaysia. Geological Journal. 56 (12), 6022–6030. DOI: 10.1002/gj.4128
• Tang H.Y., Mychko E.V., Feldmann R.M., Schweitzer C.E., Shaari H., Sone M. (2023) Validation of Malayacyclus Tang, Mychko, Feldmann, Schweitzer, Shaari & Sone, a cyclidan crustacean from the Early Carboniferous of Terengganu, Malaysia. Zootaxa. 5318 (3), 439–440. DOI: zootaxa.5318.3.10