Nineteen new species of Alycaeidae from Myanmar and Thailand (Gastropoda: Caenogastropoda: Cyclophoroidea) Author Páll-Gergely, Barna Author Hunyadi, András 0000-0003-3488-2817 hunand@freemail.hu Author Grego, Jozef 0000-0002-4977-0415 jozef.grego@gmail.com Author Reischütz, Alexander 0000-0002-8844-7004 alexander.reischuetz@gmx.at Author Auffenberg, Kurt 0000-0001-9660-6776 kurtauffenberg@gmail.com text Zootaxa 2021 2021-05-18 4973 1 1 61 journal article 6241 10.11646/zootaxa.4973.1.1 d0967b08-98d1-4ccd-b472-a678e0e57eda 1175-5326 4771958 42EB4BF2-A571-4894-9EEF-783649A27E4F Chamalycaeus krabiensis Páll-Gergely & A. Reischütz n. sp. Fig. 11 Material examined. Holotype : Thailand , Krabi Province , Phi-Phi Islands , Phi Phi Don Island , climbing rock at W end of beach in Ton Sai Bay , 7°44.011’N , 98°45.936’E , ca. 70 m a.s.l. (locality code: Th22), Mar. 2010 , A. Reischütz leg., at base of limestone rocks in the forest, NHMW 113487 (D: 3.61 mm , H: 2.62 mm ) . Paratypes : 1 shell, same data as holotype; 1 shell, Thailand , Krabi Province , Phi-Phi Islands , Phi Phi Don Island , ascent to climbing rock at W end of beach in Ton Sai Bay , 7°44.049’N , 98°45.966’E , ca. 20 m a.s.l. (locality code: Th 21), Mar. 2010 , A. Reischütz leg., at base of limestone rocks in forest, NHMW 113488 (photographed paratype : Fig. 11B, D : 3.73 mm , H: 2.37 mm ) ; 9 shells, same data as preceding, RE ; 2 shells, same data as preceding, CUMZ 5269 ; 7 shells, Thailand , Krabi Province , Phi-Phi Islands , Phi Phi Don Island , limestone rocks at Monkey Beach , 7°43.386’N , 98°46.135’E , ca. 10 m a.s.l. (locality code: Th 23), Mar. 2010 , A. Reischütz leg., RE . Other material: 4 juvenile / broken shells, Thailand , Krabi Province , Phi-Phi Islands , Phi Phi Don Island , ascent to climbing rock at W end of beach in Ton Sai Bay , 7°44.049’N , 98°45.966’E , ca. 20 m a.s.l. (locality code: Th 21), Mar. 2010 , A. Reischütz leg., at base of limestone rocks in forest, RE ; 5 juvenile /broken shells, Thailand , Krabi Province , Phi-Phi Islands , Phi Phi Don Island , limestone rocks at Monkey Beach , 7°43.386’N , 98°46.135’E , ca. 10 m a.s.l. (locality code: Th 23), Mar. 2010 , A. Reischütz leg., RE ; 7 shells, 1.5 km SE of Ao Luek Tai , 8°22.386’N , 98°44.130’E , 40–45 m a.s.l. , 16–19 Mar. 2020 , S. Aiken leg., SA ; 4 shells (one photographed here: Fig. 11C ), 1.7 km SE of Ao Luek Tai , 8°22.020’N , 98°44.004’E , 25 m a.s.l. , 19 Mar. 2020 , S. Aiken leg., in dry debris on rock, at base of limestone cliff, SA . Etymology. This new species is named for the Thai province in which it occurs. Diagnosis. A medium-sized Chamalycaeus species with R2 and R3 of almost a quarter whorl each, blunt, elongated swelling on R3, protruding inner peristome, and strongly expanded outer peristome. Description. Shell off-white to light grey; shell outline slightly oval in dorsal view; spire elevated, conical; body whorl rounded or parabolic; protoconch somewhat elevated, finely granular, rather glossy, spiral striae lacking, 1.5 whorls; R1 of 1.75–2.5 whorls, with strong, narrow, elevated, regularly arranged ribs, spaces between ribs relatively wide, fine spiral striation between ribs; boundary between R1 and R2 distinct due to change in rib density; R2 ribs more elevated than those of R1, narrow, lamella-like; ca. 26–28 ribs present; R2 and R3 of comparable lengths, covering approximately a half whorl or slightly less; boundary between R2 and R3 distinct due to rather deep constriction and change in sculpture; R3 with elongated, convex, central swelling, posterior portion almost smooth, anterior bears ribs of similar density as on R1; aperture strongly oblique to shell axis, rounded, with a very small upper (parieto-palatal) incision; boundary between inner and outer peristomes conspicuous, inner peristome strongly protruding (extreme in some specimens) and slightly expanded; outer peristome slim, strongly expanded except in umbilical region; umbilicus narrow, ca. one fourth of shell width. Measurements. D: 3.41–3.81 mm , H: 2.34–2.62 mm ( type samples). Operculum. Unknown. Differential diagnosis. Chamalycaeus reinhardti ( Mörch, 1872 ) (examined material: Great Nicobar, coll. Godwin-Austen, NHMUK 1903.7.1.2711, 1 shell) and Chamalycaeus reinhardti sabangensis ( Rensch, 1933 ) (examined material: Sumatra: Wald b. Sabang, Pulu Weh., exp. Rensch, 1927, SMF 6241, 1 paratype ) both have a narrower swelling on R3 and a more elevated spire. Distribution. This species is known from the Phi-Phi Islands and the vicinity of Ao Luek Tai town, Krabi Province , Thailand ( Fig. 3 ). Remarks. The shells from the two sites near Ao Luek Tai are slightly smaller (D: 2.8–3.3 mm ), more depressed and conical from above, have overall denser ribs, lower R3 swelling, and the outer peristome is expanded in a smaller portion of the lip. However, although these differences occur, we consider them conspecific with those from Phi-Phi Islands due to the overall similar sculpture and proportions of shell regions.