Guerrerostrongylus marginalis n. sp. 1, Ventral view of the anterior end of male, showing cephalic vesicle, esophagus, nerve ring, deirids (indicated by arrows), and excretory pore (between deirids). 2, Posterior end of a paratype, showing caudal bursa, genital cone, and spicules. 3, Lateral view of cephalic vesicle and stoma with esophageal tooth (upper left) not projected toward lumen. 4, Apical view of a female featuring dorsal tooth and triangular stoma. 5, Apical view of a male, showing dorsal tooth and triangular stoma. 6, Posterior end of a paratype showing cuticular invagination covering vulva, vulva, anus, ovejector, infundibulum, eggs in uterus, and tail.