New Taxonomic Insights into Paradraconema (Nematoda: Draconematidae) from Korea: Valid Establishment of P. tamraense sp. nov. from Jeju Island and Description of P. gangchii sp. nov. from Dokdo Island

We describe two new species of Paradraconema from subtidal sediments of Korean waters: P. tamraense sp. nov. from Jeju Island and P. gangchii sp. nov. from Dokdo Island. Although the epithet tamraense had appeared previously in the literature, it was treated as a nomen nudum and therefore lacked nomenclatural availability under the ICZN. In this study, the species is newly and validly established based on a critical reassessment of the original material, supported by new line drawings and detailed observations using differential interference contrast (DIC) and scanning electron microscopy (SEM). Paradraconema amraense sp. nov. is characterized by a slender body; pharyngeal annules bearing weakly developed longitudinal bars with smooth margins; a narrow lateral field at midbody; abundant and relatively long somatic setae; a head capsule partially covered with vacuolated ornamentation; an amphidial fovea that is elongate loop-shaped in males and circular, unispiral in females; eleven cephalic adhesion tubes (CAT); and comparatively long sublateral adhesion tubes (SlAT) and subventral adhesion tubes (SvAT). Paradraconema gangchii sp. nov. is characterized by a slender body; cuticle ornamentation with numerous longitudinal bars bearing finely crenulated margins in the pharyngeal region; sparse and short somatic setae; a head capsule fully covered with vacuolar ornamentation (reticulate under SEM); an amphidial fovea that is elongate loop-shaped in males and circular, unispiral, slightly over one coil in females; relatively short spicules (36–46 µm); eleven CAT; and relatively short SlAT and SvAT. SEM revealed several fine morphological features not previously documented in the genus, including the precise number and arrangement of CAT and detailed structures of the cuticle ornamentation and lip region. This study provides comprehensive SEM-based documentation for Paradraconema, increases the number of valid species in the genus to thirteen, and enhances our understanding of draconematid diversity in the northwestern Pacific.