This study provides the first data on the genital anatomy, jaw and radula of Guladentia subtussulcata (L. Pfeiffer, 1863). The auxiliary copulatory organ of this species is very peculiar, similar to that of Jeanneretia L. Pfeiffer, 1877, and different from that of other cepolids. It consists of an elongate, pedunculate mucus gland inserted apically on a muscular papilla and an atrial sac, all covered by a sheath. A sheath-like accessory gland is inserted at the base of the atrial sac. Another similarity with Jeanneretia is the presence of a fertilization pouch-spermatheca complex with a single exposed spermatheca. Like Jeanneretia, G. subtussulcata has an oxygnath, highly arched jaw with slight striae over the entire surface and a broad, well-developed median projection. The radula has triangular and monocuspid central and lateral teeth (the central teeth are smaller than the rest). The marginal teeth are multicuspid with the mesocone and ectocones smaller than the endocones. The similar structures of the auxiliary copulatory organ (without dart sac) and spermatheca (simple) strongly suggest that G. subtussulcata and Jeanneretia spp. are closely related. As such, it remains to be decided whether Guladentia Clench & Aguayo, 1951 and Jeanneretia should continue to be treated as separate genera.