A new actinolaim, Egtitus invaginatus n. sp. (Nematoda: Actinolaimidae) from South Korea

Egtitus invaginatus n. sp. isolated from litter soils sampled around a dead black pine was characterized using morphometrics and DNA barcodes. Egtitus invaginatus n. sp. is characterized by a medium sized body 1.67–2.12 mm long, lip region expanded, 2.1–2.5 times as wide as high, anteriorly truncate, with rounded to angular sides, offset by a depression, odontostyle 19.0–21.0 μm long or as long as the lip region diameter, pars refringens vaginae with two irregularly ovoid to D-shaped pieces, vulva flush with body contour in lateral view, a transverse slit in ventral view, vulva opening equatorial to slightly post-equatorial; one to three ventral cleft-like invaginations present at 4.0–6.0 μm posterior to anal opening, forming papilla-like outgrowth, tail straight or slightly curved ventrad, 12.5–17.5 times anal body diameter; spicules 46.5 μm long, seven spaced ventromedian supplements and male tail conoid to broadly rounded. The phylogenetic relationships among species were reconstructed using 18S-rRNA and 28S-rRNA gene sequences. The two phylogenies showed that E. invaginatus n. sp. is genetically similar to the only gene sequences of the genus available in GenBank database.