Deladenus coreanus n. sp. (Rhabditida: Neotylenchidae), a new species from South Korea.

A new species of the genus Deladenus isolated from the outer wood and bark layers of a dead red pine tree (Pinus densiflora f. erecta) was characterized using morphological and morphometric data, as well as DNA sequences. Deladenus coreanus n. sp. is characterized by the medium sized body of mycetophagous female abruptly narrowing behind vulva, lateral fields with four incisures, pharyngeal corpus without a distinct median bulb and lacking a chamber, pharyngo-intestinal junction immediately behind the nerve ring, hemizonid 13.0-37.0 μm posterior to nerve ring, excretory pore at level with hemizonid, vulva with prominently protuberant lips and with no lateral vulval flaps, post-uterine sac absent, vulva-anus distance approximately equal to tail length, tail conoid, gradually tapering to a broadly or narrowly rounded terminus, or subcylindrical and clubbed, males with slender spicules, 19.0-21.0 μm long and bursa reaching tail tip. The phylogenetic relationships were reconstructed using partial 18S rRNA, 28S rRNA, and COI gene sequences. The newly generated 18S rRNA and 28S rRNA sequences appeared as independent lineages in corresponding trees, and the new COI gene sequence formed a clade with the corresponding gene sequence of Deladenus brevis with moderate (87) Bayesian posterior probability.