Endoxocrinus (Diplocrinus) kexuei, a new species of stalked crinoid (Echinodermata, Crinoidea, Isocrinida, Balanocrinidae) from rotten wood in the cold seep area of the Taixinan Basin, South China Sea

A new species of stalked crinoid, Endoxocrinus (Diplocrinus) kexuei sp. nov. belonging to the family Balanocrinidae, is described from cold seeps in the South China Sea. The general appearance of the new species is similar to E. (Diplocrinus) alternicirrus, but can be distinguished from its congener in both morphological characteristics and significant genetic divergences. Endoxocrinus (Diplocrinus) kexuei sp. nov. shows cryptosymplexies without marked symmorphy, and an axial canal usually incompletely filled with a lattice needlelike network, preserving an irregular secondary lumen.

The new species attribution is well supported by genetic distance based on the mitochondrial c oxidase subunit I (COI), and molecular phylogenetic analyses based on COI and 16 S rRNA. This discovery enhances our understanding of species diversity of Endoxocrinus crinoids in the South China Sea.