A new species of stygobitic Hyalella Smith, 1874 (Amphipoda: Hyalellidae) from Ash Meadows National Wildlife Refuge, Nevada, USA, with discussion of the unique presence of the species in the Nearctic groundwater fauna.

The article focuses on the description of a new species of stygobitic (groundwater-dwelling) hyalellid amphipod, *Hyalella cretae* n. sp., discovered in Ash Meadows National Wildlife Refuge, Nye County, Nevada, USA. Morphological and molecular analyses distinguish *H. cretae* from its closest Nearctic groundwater relative, *Hyalella muerta*, despite their superficial similarity, indicating independent colonization events of groundwater habitats. The study discusses the biogeographic significance of these findings within the Nearctic region, noting the rarity of hypogean *Hyalella* species compared to other amphipod genera like *Stygobromus*. The research highlights the need for further taxonomic and evolutionary studies on *Hyalella* to better understand its diversity, distribution, and ecological roles, especially given the conservation concerns for groundwater habitats.