Razor clams are highly prized for their delicious taste and nutritional benefits. Species of razor clams, such as Solen grandis and Cultellus attenuatus, are particularly important in the edible shellfish market. There has been a growing interest among researchers in the artificial breeding, aquaculture, development and utilization of these species. However, the taxonomy and phylogeny of these bivalves have not received much attention.

A research team led by Prof. ZHANG Junlong from the Institute of Oceanology of the Chinese Academy of Sciences (CAS) has reported a new species named Cultellus exilis. They used an integrative taxonomic approach that included morphological comparisons, geometric morphometrics, and genetic analyses to accurately identify and classify this new species.

The study was published in Zoosystematics and Evolution on Apr. 9.

The holotype of the new species was collected with the Agassiz trawl in the South China Sea in May 2021. This species can be distinguished morphologically from other congeners by its slender valve. The geometric morphometric analyses based on valve outline data showed that samples of the new species were obviously separated from other cultellusids.

The results of three species delimitations (ABGD, bPTP, GMYC) based on mitochondrial c oxidase subunit I (COI) genes showed that this species belongs to the genus Cultellus but is genetically distinct from other known species.

In addition, the researchers performed a phylogenetic analysis of the superfamily Solenoidea based on the concatenation of three genes (COI+16S+28S). "The previously established division of the subfamily Pharellinae based on morphology is problematic and needs to be revised by combining more information and taxa," said YU Yanan, first author of the study.

The type specimens of this new species are kept in the Marine Biological Museum of CAS (MBMCAS). The researchers discovered some historical specimens collected over a century ago in the same museum that belong to this new species.

"MBMCAS has a large number of historical marine specimens, which can provide valuable materials for studying the taxonomy and phylogeny of marine organisms," said Prof. ZHANG, corresponding author of the study and also the lead curator of the museum.

The holotype of Cultellus exilis. (Image by ZHANG Junlong & YU Yanan)

The type materials of other species of the genus Culetellus. (Image by ZHANG Junlong & YU Yanan)