The polyclads (Platyhelminthes: Polycladida) from the Tropical Eastern Pacific: Commented checklist and description of a new species Author Ramos-Sánchez, Mariela E9D05B3F-CF64-48E3-B5ED-8D24E47F9D2A Doctorado en Ciencias Biológico Agropecuarias, Área Ciencias Biológico Agropecuaria y Pesquera, Ciudad de la cultura “ Amado Nervo ”, Tepic, Nayarit, 63000, Mexico. & Laboratorio de Sistemática de Invertebrados Marinos (LABSIM), Universidad del Mar, campus Puerto Ángel, Ciudad Universitaria, Puerto Ángel, Oaxaca, 70902, Mexico. rmariela220@gmail.com text European Journal of Taxonomy 2024 2024-10-17 962 1 1 67 https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2683/12419 journal article 10.5852/ejt.2024.962.2683 2118-9773 13947260 40171C5B-90EB-4641-91FF-EA8CA2C60D23 Bivesaculosuteri marcelae Ramos-Sánchez, Bahia & Bastida-Zavala, 2019 Bivesaculosuteri marcelae Ramos-Sánchez et al. , 2019: 37–41 , figs 4a–h, 5a–e, 6a–l ( type locality: Agua Blanca Beach, Puerto Escondido, Oaxaca , Mexico ). Distribution Agua Blanca Beach, Puerto Escondido, Oaxaca , Mexico . Habitat Epibiont (in Padina Adans. –Jellyella Taylor & Monks, 1997). Remarks Bivesaculosuteri marcelae is characterized by an oval to circular body, cerebral and tentacular eyes, absence of marginal eyes, and pyriform nuchal tentacles. The male reproductive system features a poorly differentiated interpolated prostatic vesicle, an oval and prominent seminal vesicle, spermiducal vesicles, and cylindrical sclerotized stylet with acicular tip. The female reproductive system features a uterine duct, a paired uterine sac, ovoid and strongly muscularized uterine vesicles, a muscularized vaginal pore located posteriorly to the female gonopore, a vaginal duct, an oval Lang’s vesicle, and poorly developed duct of Lang’s vesicle.