Siduridae

Siduridae is a taxonomic designation that has appeared in zoological literature as a family within the branchiopod crustaceans. In modern usage, Siduridae is not generally recognized as a valid family; most classifications treat Sididae, a family within the order Cladocera (water fleas), as the correct lineage, with Siduridae either considered a synonym of Sididae or as an historical name no longer in use.

Taxonomy and relationship: The status of Siduridae varies by source. Some older treatments placed certain freshwater cladoceran genera into Siduridae, but current taxonomic databases typically do not list Siduridae as an accepted family. When encountered, taxa formerly assigned to Siduridae are usually reclassified under Sididae or related families.

Description and ecology: If equated with the water fleas, sidurid taxa would be small aquatic crustaceans with a simple carapace, a laterally compressed body, and feeding appendages adapted for filter feeding. They inhabit freshwater environments such as ponds, lakes, and slow-moving rivers, where they contribute to plankton communities and serve as prey for larger invertebrates and fish.

Reproduction and life history: Cladocerans commonly reproduce by cyclical parthenogenesis, with occasional sexual reproduction under unfavorable conditions, though specifics vary among taxa historically placed in Siduridae.

Nomenclature and history: The name Siduridae reflects historical taxonomic practices; revisions and phylogenetic analyses have led to its obsolescence in favor of Sididae in many sources.