Echinoderes hakaiensis sp. nov.: a new mud dragon (Kinorhyncha, Echinoderidae) from the northeastern Pacific Ocean with the redescription of Echinoderes pennaki Higgins, 1960

Abstract

Surveys of kinorhynch diversity in the northeastern Pacific Ocean are rare, and only eight species have been described from the region so far. We explored the diversity of kinorhynchs from a pristine coastal habitat of British Columbia (Calvert Island) and discovered a new subtidal species, Echinoderes hakaiensis sp. nov. We also redescribed one of the oldest described echinoderid species, E. pennaki. Both species were characterized with high-resolution light microscopy (LM), scanning electron microscopy (SEM), and DNA sequences from the mitochondrial cytochrome c oxidase subunit 1 (COI) gene. Echinoderes hakaiensis sp. nov. can be differentiated from other species by a unique pattern of spines and tubes (i.e., four pairs of tubes on segment 2 combined with three middorsal spines). Echinoderes pennaki shows a configuration of traits on segment 2 that questions the reliability of conventional morphological characters used to distinguish different genera within the Echinoderidae. Reevaluation of these characters will require a resolved molecular phylogenetic context including a more comprehensive sampling of species within the group.