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| Bathynomus wilsoni Ahyong, 2025 RAFFLES BULLETIN OF ZOOLOGY . 73; |
Abstract
A new species of supergiant isopod, Bathynomus wilsoni, is described from the Sulu Sea, Philippines, from a depth of 2,500 m, the deepest record for the genus. Bathynomus wilsoni is the fifth Indo-West Pacific species having upcurved posterior spines on the pleotelson in adults and is readily distinguished from these species by the combination of longer posterolateral cephalic incisions, proportionally wider uropodal exopods with a more strongly convex lateral margin and a near semi-circular pleotelson with a bifid instead of simple apex on the central spine. The new species is most similar to B. kensleyi Lowry & Dempsey, 2006, from northeastern Australia, a species with which it has been previously confused, but further differs in the stouter uropodal exopod, the shape of the pleotelson and ornamentation of the anterior surface of the cephalon. Given that 26% of the 23 named extant species of Bathynomus were described within the last decade, species richness in the genus is probably significantly underestimated. Aspects of diagnostic characters of B. kensleyi and allies are also discussed.
Key words. Bathynomus, giant isopod, Sulu Sea, South China Sea, Philippines
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| Bathynomus wilsoni, new species, female holotype, 215 mm, Sulu Sea, Philippines, AM P42711: A, cephalon, oblique anterior view; B, clypeal region; C, pleotelson; D, pleotelson central spine; E, right uropod, dorsal view; F, left uropod, ventral view; G, posterior pleonites, pleotelson and uropod, right oblique lateral view; H, pleotelson, right lateral view; I, pereonites 6–7 coxal plates, pleonites 1–5 pleura, right lateral view; J, pereonites 4–7 and pleonites 1–5, right lateral view. |
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| Bathynomus wilsoni, new species, Sulu Sea, Philippines, colour when fresh: dorsal and ventral habitus: A, B, female holotype, 215 mm, AM P42711; C, D, male paratype, 212 mm, ZRC 2025.0098. (Photographs: G.D. Wilson). |
Bathynomus wilsoni, new species
Diagnosis. Cephalon anteromedian surface without shallow,
irregularly ridged sulcus; cephalic ridge above eyes
discontinuous; maxillipedal somite incisions deep, extending
inward from posterolateral margin for length equivalent to
about ⅓ distance between left and right incisions. Pleonites
1–5 combined length 17–18% body length; pleonites 3–5
pleural apices extending posteriorly to about same level or ...
Etymology. The type specimens were collected during the
Scripps Institution of Oceanography expedition, PAPATUA,
and brought to the Australian Museum by George D. F. (Buz)
Wilson, my former Professor. It is most fitting to name the
new species after Buz.
SHANE T. AHYONG. 2025. The Deepest known Supergiant deep-sea isopod: Bathynomus wilsoni, A New Species from the Sulu Sea, Philippines (Crustacea: Isopoda: Cirolanidae). RAFFLES BULLETIN OF ZOOLOGY . 73; 169–183.
