Taxonomic review of Korean Siphonaria Species (Mollusca, Gastropoda, Siphonariidae)

Many molluscan species exhibit a high degree of shell morphological plasticity in their shape (including sculptures), size, and color patterns, which can vary significantly depending on environmental conditions. These shell morphological variations make it challenging to differentiate species based on morphology alone, often resulting in various taxonomic errors, such as misidentifications, overlooking cryptic species diversity, or a plethora of nominal species. The genus Siphonaria constitutes a significant component of the macrobenthic invertebrate fauna in intertidal habitats across temperate to tropical region. Given the limited attention to shell variation in previous taxonomic studies on the Korean Siphonaria species, the extensive range of ecophenotypic shell variations documented in this group raises questions about the taxonomic validity of previously reported in Korean Siphonaria species.

The present study provides a comprehensive taxonomic review of Korean Siphonaria species using a combination of shell morphology, radula structure, and phylogenetic analysis of the mtDNA cox1 sequences. This integrative analysis confirmed the validation of S. acmaeoides , S. japonica , and S. sirius in Korea, highlighting differences in shell and siphonal groove morphology among these species. Detailed descriptions of shell and radula characteristics, along with mtDNA cox1 sequences as DNA barcodes, are also provided, which is very useful for the accurate identification of Siphonaria species. Considering geographic distribution range of the Siphonaria species, the present study questions the validity of S. javanica , S. laciniosa , and S. rucuana previously reported in Korea, suggesting potential misidentifications of shell variants in the Korean malacofauna. Further research with extensive taxon sampling is needed to clarify these taxonomic ambiguities.