Bursa bufonia (Gmelin, 1791). (Synonym: Ranella luteostoma Pease, 1861a.) Length, 80 mm; diameter, 49 mm. Shell: somewhat depressed with lateral varices and siphonal canals; sculpture of knobbed spirals and finer threads; shell and perture white, cream, or yellow. Spire: rather obtuse, suture obscured, whorls somewhat flattened. Sculpture: encircled by knobbed spiral threads with finer threads between. Aperture: ovate; outer lip irregularly denticulate, edge frilled; columella plicate. Color: white or cream with brown markings; aperture white or yellow within, denticles white. These gastropods are infrequently encountered in shallow water, and are collected at depths of 20 m. Their habitat in the Hawaiian Islands is in contrast to the habitat elsewhere in the Pacific; in Micronesia the species is recorded as "abundant along the windward shores of Bikini, Eniwetok, Rongelap, and Ronerik" (Demond. 1957).

Bursa bufonia was recorded previously from the Marquesas Islands by Trondle and Cosel (2005: 288). It is recognisable by being much the largest and heaviest of the shallow-water, short-spired Bursa species, reaching c. 90 mm in height. The surface of most specimens is sculptured with large, low, rounded nodules, and most specimens are encrusted with algae, even when collected alive. Throughout most of its range the shell exterior is pale grey with irregular small black or dark brown flecks. Many of the Marquesan specimens have dark brown flecks in the small hollows of the primary spiral cords, giving them a darker colour pattern than usual, so that they resemble southern Japanese specimens of the dunkeri form. Unlike most other Bursa species, the interior of the aperture is plain white, although it bears the closely spaced transverse ridges on the inner lip that are present in all other Bursa species.

Bursa bufonia, the type species of Bursa, occurs widely in the central Indo-West Pacific, from East Africa and Mauritius to an eastern limit at the Marquesas and Tuamotu Islands. Richard (1985) and Trondle and Boutet (2009) recorded B. bufonia from all island groups of French Polynesia, and these records are confirmed by the material listed here. It is largely replaced in Hawaii by the similar but taller, narrower, more elaborately sculptured, restricted Hawaiian species Bursa luteostoma (Pease, 1861) (Kay 1979: fig. 80G, identified as B. bufonia; Severns 2011: 150, pi. 59, fig. 5), but a single authentic Hawaiian specimen of B. bufonia in a private collection has been shown to us (Severns 2011: 154, pi. 61, figs 2a, b). In the north of its range, in southern Japan (particularly the Ryukyu Islands), some specimens of B. bufonia are more colourful than the usual pale grey form, and have been provided with the name Bursa dunkeri Kira, 1959, but they intergrade completely with paler shells. The Hawaiian specimen (Severns 2011) also is this colour form. B. bufonia does not occur in New Caledonia or northern Australia, and seems to extend only as far south as northern Papua New Guinea. Kohn (1983: 28, fig. 2) illustrated B. bufonia predating echinoids such as Echinometra in the same way as Charonia, so the distribution of B. bufonia is likely to be controlled by the occurrence of its echinoid prey. The MNHN Marquesan material studied here was all collected in the intertidal zone at Ua Huka, but it occurs moderately commonly (14 specimens examined) and reaches a large size. Also, the other Marquesan material listed above demonstrates that it occurs also at Tahuata and Ua Pou Islands. Specimens are fairly common in Tahiti (Society Islands; six localities recorded above) and the Tuamotu Islands (eight localities reported above), and two specimens are reported from the Austral Islands.