Mid-Holocene marine faunas from the Bangkok Clay deposits in Nakhon Nayok, the Central Plain of Thailand Author Jirapatrasilp, Parin 0000-0002-5591-6724 Animal Systematics Research Unit, Department of Biology, Faculty of Science, Chulalongkorn University, Bangkok 10330, Thailand & Leibniz-Institut zur Analyse des Biodiversitätswandels - Standort Hamburg, Martin-Luther-King-Platz 3, Hamburg 20146, Germany Author Cuny, Gilles 0000-0001-7680-1697 Université Claude Bernard Lyon 1, LEHNA UMR 5023, CNRS, ENTPE, F- 69622, Villeurbanne, France Author Kocsis, László 0000-0003-4613-1850 Institute of Earth Surface Dynamics, University of Lausanne, Rue de la Mouline, 1015 Lausanne, Switzerland Author Sutcharit, Chirasak 0000-0001-7670-9540 Animal Systematics Research Unit, Department of Biology, Faculty of Science, Chulalongkorn University, Bangkok 10330, Thailand Author Ngamnisai, Nom Department of Geography, Faculty of Social Sciences, Srinakharinwirot University, Bangkok 10110, Thailand Author Charoentitirat, Thasinee Animal Systematics Research Unit, Department of Biology, Faculty of Science, Chulalongkorn University, Bangkok 10330, Thailand Author Kumpitak, Satapat Animal Systematics Research Unit, Department of Biology, Faculty of Science, Chulalongkorn University, Bangkok 10330, Thailand Author Suraprasit, Kantapon 0000-0002-3428-9549 Animal Systematics Research Unit, Department of Biology, Faculty of Science, Chulalongkorn University, Bangkok 10330, Thailand text ZooKeys 2024 2024-05-15 1202 1 110 journal article 10.3897/zookeys.1202.119389 D04EE090-0D05-4EB2-ADA6-3EE4E19F59D9 Cylichna modesta Thiele, 1925 Figs 4 R , 10 B Cylichna modesta Thiele, 1925: 241–242 [275 – 276], pl. 44 [32], fig. 7. Type locality: “ Neu-Amsterdam ”, Station 167 (37 ° 47 ’ südl. Br., 77 ° 33.7 ’ östl. L., 496 m ). Swennen et al. 2001: 137 , fig. 497. Wells et al. 2021: 144 . Adamnestia modesta . Robba et al. 2004: 230 , pl. 34, fig. 5 a, b. Robba et al. 2007: 97 (appendix). Negri et al. 2014 : table 3. Referred material. CUF - NKNY - G 39 (11 shells; Figs 4 R , 10 B ). Habitat. Sublittoral in muddy or fine sandy bottoms ( Robba et al. 2004 ). Distribution. Southwest Pacific. Records of fossils from the Holocene in Thailand ( Robba et al. 2004 ). Record in Thailand . Gulf of Thailand ( Wells et al. 2021 ). Taxonomic remarks and comparisons. This species differs from its similar species, Cylichna sibogae Schepman, 1913 , by having a less slender shell and an adapical umbilicus unbounded by sharp angulation ( Robba et al. 2004 ). The generic assignment to either Adamnestia Iredale, 1936 or Cylichna requires further investigation. Subcohort Panpulmonata Jörger et al., 2010 Superorder Eupulmonata Haszprunar & Huber, 1990 Order Ellobiida Van Mol, 1967 Superfamily Ellobioidea Pfeiffer, 1854