This study reports two novel species, Gogorevia contracta sp. nov. and G. recticentralis sp. nov., which were isolated from freshwater environments in South Korea. Using an integrative taxonomic approach, we conducted morphological analyses using light microscopy and scanning electron microscopy, along with molecular phylogenetic investigations using SSU rRNA and rbcL gene sequences. Phylogenetic reconstructions highlighted the distinct characteristics of both species, confirming their classification within the genus Gogorevia and elucidating their evolutionary relationships. Morphologically, G. contracta was characterized by a bow-tie-shaped central area and circular depressions in the rapheless valve, whereas G. recticentralis exhibited a rectangular-to-wedge-shaped central area with parallel striae near the center of the raphe valve. Our findings highlighted the ecological significance of Gogorevia species and suggested their potential role as bioindicators of water quality in relatively unpolluted freshwater systems. Over the past decade, our research has focused on the taxonomic and ecological study of diatoms in the Han River system and identified 136 species, including nine newly described taxa. The findings of the present study contribute to a growing understanding of Gogorevia diversity, underscore the importance of region-specific diatom indices, and support the integration of morphological and molecular methods into diatom systematics.

This study reports the discovery of four novel Pinnularia species—P. latocentra sp. nov., P. rhombocentra sp. nov., P. seouloflexuosa sp. nov., and P. paristriata sp. nov.—from urban freshwater streams in South Korea. Species delimitation was achieved using a polyphasic approach that integrated light and scanning electron microscopy, ecological profiling, and molecular evidence from SSU rRNA and rbcL sequences. Each taxon was confirmed as morphologically and genetically distinct from its closest congeners. Our findings broaden the recognized diversity of Pinnularia in East Asia and demonstrate that urban streams, often regarded as degraded habitats, can harbor hidden diatom diversity and ecological complexity. By clarifying diagnostic traits, validating type material in a recognized repository, and aligning molecular and morphological evidence, this study contributes to a more robust taxonomy of Pinnularia. These results also highlight the importance of polyphasic taxonomy and the strategic inclusion of urban habitats in diatomological surveys and biodiversity assessments.

Diatoms (Bacillariophyta) are among the most diverse and ecologically significant microalgae, contributing nearly one-fifth of global carbon fixation and driving the biogeochemical silicon cycle (R...