Conclusions

The formal descriptions of Princaxelia malohi sp. nov. and Princaxelia kahat sp. nov. are presented expanding the known diversity of large predatory amphipods inhabiting the hadal zone and highlighting how much remains unresolved about predator-prey dynamics below 8,000 m. Together, the new morphological descriptions, genetic data, and in situ behavioural observations show that Princaxelia is not simply a rare taxonomic curiosity, but a potentially important predator within hadal amphipod communities. Continued collection of specimens, combined with high-resolution imaging, molecular data, and video observations, will be essential for resolving the true diversity, distribution, and ecological role of this genus. These findings reinforce that even among the most conspicuous animals of the deepest trenches, fundamental aspects of taxonomy, behavior, and food-web structure remain poorly understood.