An updated inventory of sea slugs from Koh Tao, Thailand, with notes on their ecology and a dramatic biodiversity increase for Thai waters Author Mehrotra, Rahul Reef Biology Research Group. Department of Marine Science, Faculty of Science, Chulalongkorn University, Bangkok 10330, Thailand & Aow Thai Marine Ecology Center, Koh Mun Nai, Kram, Klaeng District, Rayong 21110, Thailand Author A. Caballer Gutierrez, Manuel American University of Paris, Department of Computer Science Math and Environmental Science, 6 rue du Colonel Combes, 75007 Paris, France & Museum national d'Histoire naturelle, 55 rue de Buffon, 75005 Paris, France Author M. Scott, Chad Conservation Diver. 7321 Timber Trail Road, Evergreen, Colorado, 80439, USA Author Arnold, Spencer Conservation Diver. 7321 Timber Trail Road, Evergreen, Colorado, 80439, USA Author Monchanin, Coline Aow Thai Marine Ecology Center, Koh Mun Nai, Kram, Klaeng District, Rayong 21110, Thailand & Research Center on Animal Cognition (CRCA), Center for Integrative Biology (CBI); CNRS, University Paul Sabatier, Toulouse III, France Author Viyakarn, Voranop https://orcid.org/0000-0002-2089-6356 Reef Biology Research Group. Department of Marine Science, Faculty of Science, Chulalongkorn University, Bangkok 10330, Thailand Author Chavanich, Suchana https://orcid.org/0000-0001-6266-7300 Reef Biology Research Group. Department of Marine Science, Faculty of Science, Chulalongkorn University, Bangkok 10330, Thailand & Center of Excellence for Marine Biotechnology, Department of Marine Science, Faculty of Science, Chulalongkorn University, Bangkok 10330, Thailand suchana.c@chula.ac.th text ZooKeys 2021 2021-06-09 1042 73 188 http://dx.doi.org/10.3897/zookeys.1042.64474 journal article http://dx.doi.org/10.3897/zookeys.1042.64474 1313-2970-1042-73 9CF986D86A474E179A67245C78FB8AFD 1BB0A10A35DD5541850FDAFFDB7119C2 Aeolidiopsis harrietae Rudman, 1982 Figure 16L Material examined. Two specimens 21-29 mm , LB; one specimen 17 mm , SRB. Ecology. Cryptic on their prey, Palythoa sp. which has thus far only been recorded growing on isolated pieces of rubble or artificial substrate (i.e., discarded plastic) in deeper soft sediment habitats outside the coral reef. Distribution. Known from Japan ( Ono 2004 ), Australia ( Rudman 1982 ), the Philippines and Papua New Guinea ( Gosliner et al. 2008 ). Previously recorded from the Gulf of Thailand ( Mehrotra and Scott 2016 ). Remarks. Specimens from Koh Tao have papillate rhinophores (similar to Carmona et al. 2014a : fig. 3D) with distinctly white tips, have between 4-6 cerata per row which are the same brown colour as the dorsum with distinctive yellowish to pale brown cnidosacs.