Abstract

A new species of Encotyllabe Diesing, 1850 (Monopisthocotylea: Capsalidae), Encotyllabe tantaliani n. sp., is described from the pharyngeal plates of the Lorna drum, Sciaena deliciosa (Tschudi, 1846) (Eupercaria: Sciaenidae), collected from two localities along the Peruvian coast. This new species was originally proposed as E. callaoensis Tantaleán, 1974, in an unpublished doctoral thesis, and is herein recognized as a nomen nudum under the International Code of Zoological Nomenclature (ICZN). Encotyllabe tantaliani n. sp. is distinguished from all known congeners by the following combination of morphological features: (1) an anteriorly tapering body proper, (2) slightly lobed testes markedly larger than the ovary, (3) vitelline follicles beginning at the level of the male copulatory organ (MCO) and absent from the regions of the reproductive organs, (4) a genital pore positioned posterolateral to the pharynx, and (5) an oblong-shaped MCO. Phylogenetic analysis based on cox1 sequence places E. tantaliani n. sp. in a clade with Encotyllabe percussa Morales-Ávila, Jufaili & Ogawa, 2024, a parasite of Lethrinus nebulosus (Forsskål, 1775) (Eupercaria: Lethrinidae) from the Arabian Gulf. Pairwise genetic distances support the distinctiveness of the new species from its closest congeners. Encotyllabe tantaliani n. sp. represents the first species of the genus described from a host belonging to the Sciaenidae host. © 2025 by the authors.