Paraplanocera angeli Soutullo, Cuadrado & Norena 2021

Paraplanocera angeli Soutullo, Cuadrado & Noreña, 2021 Paraplanocera angeli Soutullo et al., 2021: 368–369, fig. 3b–d (type locality: Playa Langosta Beach, Las Baulas National Marine Park of Guanacaste, Costa Rica). Distribution Playa Langosta Beach, Las Baulas National Marine Park of Guanacaste, Costa Rica. Habitat Benthic. Remarks Prudhoe (1945: 197–198, figs 1–2) divided the genus into two groups based on the internal morphology of the male reproductive system and thereby reduced the genus to three species (P. oligoglena (Schmarda, 1859), P. aurora Laidlaw, 1903, and P. marginata Meyer, 1922), these groups were characterized by the following characters: Group 1: Cirrus cavity lined with numerous spines (comparatively they are largest near the male atrium); the spermiducal duct (= the seminal vesicle canals) opens into the ventral wall of the prostatic vesicle. Group 2: Cirrus cavity lined with numerous small spines with a pair of conspicuous sclerotized projections (teeth); the spermiducal duct opens into the prostatic duct just before entering the cirrus sac. However, Hyman (1955b) and Faubel (1983) considered the criteria proposed by Prudhoe (1945) for species reduction to be inadequate. They argued that these criteria lacked a thorough review of characters, presented unsatisfactory descriptions, and omitted certain features, in particular the presence or absence of accessory prostatic vesicles and the glandular pouch of the male atrium. The latter character was used by Kato (1936) to divide the species of the genus into two groups (Prudhoe 1945). Consequently, Faubel (1983) validated ten species for the genus (P. oligoglena, P. aurora, P. discus (Willey, 1897), P. fritillata Hyman, 1959, P. langii angi (Laidlaw, 1902), P. marginata, P. misakiensis Yeri & Kaburaki, 1918, P. oceanica (Hyman, 1953), P. rotumanensis Laidlaw, 1903 and P. rubrisfasciata Kato, 1937). Recently, two new species have been added: Paraplanocera angeli (Soutullo et al. 2021) and Paraplanocera oligoglenoides (Ramos-Sánchez et al. 2019); however, the present study suggests a detailed review of the existing biological material for the described species in the genus together with the re-evaluation of each of the characteristics that define the species. Paraplanocera angeli has a translucent coloration pattern, a cirrus sac that lacks sclerotized adenoids, and a smooth, ciliated Lang’s vesicle (Soutullo et al. 2021).