A New Bivalve Species of the Genus J. E. Gray, 1828 (Bivalvia, Venerida, Cyrenoidea, Glauconomidae), from Shandong, China.

The family Glauconomidae has few species, limited molecular data description, and insufficient research attention. The biodiversity of Glauconomidae within China deserves further exploration. In recent years, the taxonomic status of Glauconomidae has undergone changes, and some studies have found a close relationship between Glauconomidae and the family Cyrenidae based on molecular data, suggesting that Glauconomidae should be classified under the superfamily Cyrenoidea. However, both domestic and international research has mainly focused on only four species of Glauconomidae, indicating an urgent need for more species data support. Recently, 46 specimens of Glauconomidae were collected in the Yellow River Estuary in Dongying City of Shandong Province in China. Through a comparative analysis of shell morphology and molecular phylogenetic analysis of and , two species of Glauconomidae was discovered. One is Reeve, 1844, and the other is a new species of Glauconomidae found in the Yellow River, named sp. nov. The sp. nov. exhibits distinct differences in shell shape and shell color compared to other species of Glauconomidae, resembling . There are also significant differences in shell color, shell sculpture, ligament size, and shell thickness. Furthermore, the molecular phylogenetic analysis based on and genes supports the validity of sp. nov. as a species. It indicates a close phylogenetic relationship with , making them sister species. This study provides a redescription of the morphological characteristics of and sp. nov., laying the foundation for the morphological classification, biodiversity research, and conservation of Glauconomidae species.