First study of the Polycladida (Rhabditophora, Platyhelminthes) from the Pacific Coast of Costa Rica Author Soutullo, Patricia 0000-0002-9691-0038 Dept. Biodiversidad y Biología Evolutiva, Museo Nacional de Ciencias Naturales (CSIC). José Gutiérrez Abascal 2, Madrid, Spain. Patricia Soutullo: patriciasoutullo @ gmail. com; https: // orcid. org / 0000 - 0002 - 9691 - 0038 patriciasoutullo@gmail.com Author Cuadrado, Daniel 0000-0002-9691-0038 Dept. Biodiversidad y Biología Evolutiva, Museo Nacional de Ciencias Naturales (CSIC). José Gutiérrez Abascal 2, Madrid, Spain. Patricia Soutullo: patriciasoutullo @ gmail. com; https: // orcid. org / 0000 - 0002 - 9691 - 0038 patriciasoutullo@gmail.com Author Noreña, Carolina 0000-0002-9691-0038 Dept. Biodiversidad y Biología Evolutiva, Museo Nacional de Ciencias Naturales (CSIC). José Gutiérrez Abascal 2, Madrid, Spain. Patricia Soutullo: patriciasoutullo @ gmail. com; https: // orcid. org / 0000 - 0002 - 9691 - 0038 patriciasoutullo@gmail.com text Zootaxa 2021 2021-04-22 4964 2 363 381 journal article 7069 10.11646/zootaxa.4964.2.7 c36b481b-c2c3-4f7c-b5b9-614607673bb8 1175-5326 4709585 7E356498-C414-4B75-A3E5-5E9E85291BBB Enchiridium magec , Cuadrado, Moro & Noreña, 2017 (Fig. 5) FIGURA 5. Enchiridium magec Cuadrado, Moro & Noreña, 2017 . A. Distribution map and sample points; B. Whole live animal, dorsal view; C. Ventral view of whole live animal; D-E. Histological sections of the copulatory organs stained with Azan; F. Sagittal reconstruction of the reproduction system (D, E, F anterior end to the right). Material examined : Two specimens. One fixed in Bouin and one sagittal sectioned and stained with Azan. Deposited in the National Museum of Natural Sciences. 49 slides: MNCN 4.01/2412 to MNCN 4.01/2460 Location: Both specimens were collected in Playa Carbon ( Las Baulas National Park of Guanacaste , Costa Rica ) 10 ° 20’53.4 “N 85 ° 51’44.5” W ; 19, May, 2018 (Fig 5A) Habitat: Low intertidal, below stones on sand. Description : External features (Fig.5B, C): Body shape elongated with smooth dorsal surface. Background colour yellow with cream dots and dark brown spots in the central area, forming a continuous longitudinal midline. Ventral colouration whitish. Without pseudotentacles or tentacles. With marginal eyes in the first third of the body and two elongated clusters of cerebral eyes. Tubular pharynx located in the anterior third of the body, anteriorly oriented. Reproductive system: Male copulatory apparatus with a single male gonopore (Fig. 5C), anterior to the female. With an elongated penis papilla armed with a long tubular stylet (Fig. 5E). Two interpolated prostatic vesicles, included in a very characteristic muscular bulb, and the seminal vesicle surrounded in a second muscular bulb (Fig. 5D). The female copulatory apparatus presents a short vagina, oriented posteriorly, surrounded by cement glands (Fig. 5F). Distribution: Enchiridium magec has been found in the Atlantic Ocean, Canary Islands, ( Cuadrado et al., 2017 ) and in Costa Rica in this study. It is the first record for the Pacific Ocean and for the American west coast, Costa Rica .