Genus-level revision of the Alycaeidae (Gastropoda, Cyclophoroidea), with an annotated species catalogue Author Pall-Gergely, Barna Plant Protection Institute, Centre for Agricultural Research, Herman Otto ut 15, Budapest, H- 1022, Hungary https://orcid.org/0000-0002-6167-7221 pallgergely2@gmail.com Author Sajan, Sheikh Zoological Survey of India, Prani Vigyan Bhawan, M Block, New Alipore, Kolkata 700053, West Bengal, India & Wildlife Institute of India, Chandrabani, Dehradun 248 002, Uttarakhand, India https://orcid.org/0000-0002-2785-6824 Author Tripathy, Basudev Zoological Survey of India, Prani Vigyan Bhawan, M Block, New Alipore, Kolkata 700053, West Bengal, India Author Meng, Kaibaryer National Zoological Museum of China, Institute of Zoology, Chinese Academy of Sciences, Beijing, China Author Asami, Takahiro Department of Biology, Shinshu University, Matsumoto 390 - 8621, Japan https://orcid.org/0000-0001-5706-0272 Author Ablett, Jonathan D. Mollusca Section, Invertebrates Division, Department of Life Sciences, The Natural History Museums, London SW 7 5 BD, United Kingdom text ZooKeys 2020 981 1 220 http://dx.doi.org/10.3897/zookeys.981.53583 journal article http://dx.doi.org/10.3897/zookeys.981.53583 1313-2970-981-1 5194AAC86B8A473F8A41470A60182A0B 7C44C797C4125A71BAE032A55E6FA5DC Dioryx compactus (Bavay & Dautzenberg, 1900) Alycaeus (Dioryx) compactus Bavay & Dautzenberg, 1900a: 119-120. Alycaeus (Dioryx) compactus - Bavay and Dautzenberg 1900b : 454, pl. 11, figs 9, 10. Dioryx compactus - Kobelt 1902 : 337-338; Varga 1972 : 136, figs 15, 16; Pall-Gergely et al. 2017 : 10, fig. 4C. Type locality. "Bac-Kan" . Material examined. Tonkin, Bac-Kan, leg. Messager, MNHN-IM-2000-31796 (1 syntype). Remarks. Five shells in the Senckenberg Museum (Tonkin, Bac-Kan, Cho-Ra, leg. Messager, coll. Rolle ex coll. Bosch, SMF 192287) were labelled as syntypes, although they clearly belong to a different species than the single syntype in MNHN Paris, which agrees with the figures in Bavay and Dautzenberg (1900b) . This single shell is identical to Dioryx distortus , but smaller. A comprehensive revision would probably reveal that the two names are synonyms. The following remarks are based on the syntype from Paris: protoconch matte; R1 with irregular, very weak, widely spaced ribs and dense spiral striae of the same strength, although due to small space between spiral striae, they are much more conspicuous than the rare radial lines; R2 long, with very thin lighter and darker thicker stripes, the overall surface is smooth, glossy.