20.500.12556/RUL-190629 Embryonic and early postembryonic development of the freshwater isopod crustacean Asellus aquaticus - staging based on morphology The developmental biology of arthropods has advanced rapidly in recent decades, largely through the application of novel experimental techniques to a limited number of established model organisms. Extending comparative embryology beyond these traditional models is essential for a comprehensive understanding of arthropod evolution. Among crustaceans, the freshwater isopod Asellus aquaticus Linnaeus (1758) represents a promising emerging evo-devo model. This widespread European species inhabits diverse freshwater environments, including groundwater, resulting in pronounced phenotypic variation, most apparent in cave-adapted populations. It is easy to culture in the laboratory, reproduces year-round, and produces numerous accessible embryos with relatively fast development. Here, we present the most comprehensive developmental staging system for A. aquaticus to date. Using light microscopy, fluorescence microscopy with DAPI staining, and transmission electron microscopy, we integrate event-based and age-based landmarks to define nine embryonic stages (S1–S9) and a first postembryonic, premanca stage (S10). We further provide a coarse description of postembryonic development through mancae and juveniles to sexual maturity and provide a practical guide for non-invasive staging of embryos within intact marsupia of live gravid females. This refined staging framework resolves ambiguities in previous descriptions and provides a precise temporal backbone for comparative and functional evodevo studies of arthropods. It enables detailed investigations of developmental divergence between surface and cave populations, facilitates field-based studies of reproductive phenology and environmental effects on development, with potential applications in climate-change biology. Together, these advances establish A. aquaticus as a powerful model for studying the evolution of development across environmental gradients and adaptive transitions. embryonic development arthropods staging system Asellus aquaticus Isopoda Crustacea embrionalni razvoj členonožci opis razvojnih stadijev Asellus aquaticus Isopoda Crustacea true false true Angleški jezik Slovenski jezik Članek v reviji 2026-10-30 14:35:37 2026-10-30 14:35:38 2026-10-31 04:34:10 0000-00-00 00:00:00 2026 0 0 Str. 1-20 article 101574 Vol. 95 0000-00-00 Zaloznikova Objavljeno NiDoloceno 0000-00-00 0000-00-00 0000-00-00 595.2/.7 1467-8039 10.1016/j.asd.2026.101574 303266051 RAZ_Bogataj_Urban_2026.pdf RAZ_Bogataj_Urban_2026.pdf 1 79B877AFE35340E0D97D50C3C4E11EFF 086b4e3f488ac23b68c8d65684d200fdfb25fa4152ebbe7953bc981b68c065b4 1f37729f-d467-11f1-aea2-0050569b8976 https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=252184 https://www.sciencedirect.com/science/article/pii/S146780392600068X 0 2f179587-d467-11f1-aea2-0050569b8976 https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=252185 Biotehniška fakulteta 0 0 0