Allonautilus

Allonautilus is a genus of nautilus containing two living species, Allonautilus scrobiculatus and Allonautilus perforatus, both markedly different from the related genus Nautilus, its sister taxon, in shell and soft body form. Comparisons of mitochondrial genomes indicate that Allonautilus represents the oldest divergence among the living nautiloids. Allonautilus scrobiculatus, known as the crusty nautilus, is found around Papua New Guinea and the Solomon Islands, while Allonautilus perforatus, the Bali chambered nautilus, is known from Bali and Papua New Guinea. Both species live in deep water, are less studied than the shallower dwelling Nautilus species, and are protected under CITES Appendix II.