Brissopsis pohangensis sp. nov., a New Echinoid Species (Spatangoida) from the Middle Miocene Duho Formation, Pohang Basin, Korea

Abstract

A new species of spatangoid echinoid, Brissopsis pohangensis sp. nov., is described based on morphological, systematic, and taphonomic analyses of fossil material collected from the Middle Miocene Duho Formation in the Pohang Basin, southeastern Korea. A total of 428 specimens were recovered as a dense habitat assemblage from a single locality, most of which are preserved as two-dimensionally flattened tests. This unusual preservation suggests that death and burial occurred nearly simultaneously, contrasting with the typical three-dimensional preservation observed in most fossil echinoids. While the new species shares the diagnostic features of the genus Brissopsis, it is clearly distinguished from its congeners by the shape of its petals, the deeply indented fasciole pattern, and the considerable variation in labral plate length. This study represents the first formal description of a Cenozoic spatangoid echinoid species from Korea and provides important paleontological evidence for reconstructing Miocene marine ecosystems and depositional environments in the East Asian region. This discovery fills a significant gap in the fossil record of spatangoid echinoids in East Asia and provides a critical basis for future comparative studies.