Hexabranchus giganteus Tibiriçá, Pola & Cervera, 2023

Photographed by: 遠藤彩子
Location: Unse, Kerama(Kuro･Tokashiki･Gisippu･Mae), Okinawa, Japan
Date
Length: 50mm
Depth: 10.0m
Water temperature: 29.0℃

MORPHOLOGY

Commonly up to 500 mm (with some reports to 700 mm in Madagascar). The notum of resting, mature animals is evenly pustulate (“quilted”). The body of mature animals is oval. The mantle is wide, expanding, and rolled on the sides and posteriorly (but not anteriorly). The foot extends slightly beyond the mantle. There are five to eight multi-pinnate gill branches separated in gill pockets. The anus is on an elevated papilla located in the center of the gill branches. The kidney pore is on the right side of the anus. The rhinophore clubs are elongate and slightly bent with approximately 80 lamellae (in large, mature individuals). The oral tentacles are large, fleshy, and elongated.

DISTRIBUTION

Western Pacific and Western Indian Ocean. Red Sea (Yonow, 2008), Djibouti, Yemen (Debelius, 1996), Mozambique (Tibiriçá et al., 2017), Seychelles, Madagascar (Debelius & Kuiter, 2007), Tanzania (Debelius, 1996), South Africa (pers. obs.), Hong Kong (Yonow, 2008), New Caledonia (Hervé, 2010), Indonesia (Tonozuka, 2003; Valdés, 2002), Papua New Guinea (Colin & Arneson, 1995; Debelius, 1996), Japan (Nakano, 2018) including Okinawa (Coleman, 2008). On-line sources: Oman, Philippines (iNaturalist), Emirates Arab (MedSlug), Mayotte (South-west Indian Ocean Seaslug site), Vanuatu (Underwater Australasia), and Fiji (Sea Slug Forum).