The fourth-stage larva of Tridentoinfundibulum gobi, one of the rare species of Cyathostominae, is identified and described. The larva was identified as T. gobi as a result of finding molting forms showing characteristics of both larvae and adults. The buccal capsule is large and spherical; its width exceeds its depth. The buccal capsule walls are thick, gradually narrowed to the apical edge and abruptly narrowed to the posterior edge. The esophageal funnel has 3 large, triangular teeth projecting into the buccal cavity similar to those of Triodontophorus spp. and Gyalocephalus capitatus. The fourth-stage larva of T. gobi can be distinguished by its buccal capsule having a smaller diameter than the esophagus. In addition, the buccal capsule of T. gobi fourth-stage larvae is wider than deep but is as deep or deeper than wide in the fourth-stage larvae of Triodontophorus spp., and the buccal teeth of T. gobi fourth-stage larvae are much more steeply pointed and have smoother anterior edges than those of G. capitatus.