Introducing Haploniscus hades, isopod of the underworld.
The deep sea is the largest yet least explored biome in the world, with estimates suggesting that up to 91% of marine species are yet to be discovered.
Indeed, when it comes to finding new species in the deep sea, things are more than a little tricky. Besides the obvious difficulties associated with scouring such vast, inaccessible depths, researchers also face the obstacle of so-called ‘cryptic’ species: groups of closely related taxa that are almost impossible to tell apart from looks alone.
The recently discovered Haploniscus belyaevi isopod species complex is one such group, collected from the the abysso-hadal Kuril-Kamchatka Trench (KKT) region in the Northwest Pacific Ocean.
Isopods collected from the region were initially believed to represent a single species, but are now known to represent at least six distinct species, five of which are new to science. Published in the journal Zoosystematics and Evolution, a new study combines classical morphology with DNA barcoding, confocal laser scanning microscopy, and the first-ever genomic sequencing of Haploniscidae isopods to distinguish these cryptic species.
In the research paper, lead author Dr Henry Knauber and his colleagues from the Senckenberg Research Institute and Goethe University Frankfurt provide detailed descriptions of each species and reveal the names of the new species, inspired by Greek mythology.
Meet the new isopods
Haploniscus hades
Who else could rule the hadal zone but Hades himself? This isopod’s pleotelson (tail segment) hides its uropods (tail appendages), which, to the endlessly creative research team, evoked the cap of invisibility used by Hades.
Haploniscus apaticus
Named after Apate, the goddess of deceit, this ‘deceptive’ isopod hides in plain sight thanks to its unassuming looks, which kept it hidden amongst its sibling species until recently.
Haploniscus erebus
Bearing the name of Erebus, the primordial god of darkness, this species lurks in the shadowy depths.
Haploniscus kerberos
Named after Kerberos (Cerberus), the multi-headed guardian of the underworld’s gates, this species is currently only known from the abyssal plains, watching over the borderlands between deep and deeper.
Haploniscus nyx
Nyx, the goddess of night, lends her name to this elusive species.
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The isopod specimens were collected during deep-sea research expeditions between 2012 and 2016, covering depths of up to 8,000 meters.
While the names of these species represent little more than creative fun, the study’s findings help illuminate evolutionary processes across natural barriers such as the Kuril-Kamchatka Trench and underscore the potential for new discoveries in Earth’s least explored environments.
Who knows, perhaps Haploniscus hades has two brothers, H. zeus and H. Poseidon, hiding above, still waiting to be found.
Original source
Knauber H, Schell T, Brandt A, Riehl T (2025) Across trench and ridge: description of five new species of the Haploniscus belyaevi Birstein, 1963 species complex (Isopoda, Haploniscidae) from the Kuril-Kamchatka Trench region. Zoosystematics and Evolution 101(2): 813-853. https://doi.org/10.3897/zse.101.137663
Cover image credit: Isopods: Knauber et al.; Illustration: macrovector/Freepik.
