Paraplanocera oligoglena

Paraplanocera oligoglena (Schmarda, 1859) Stylochus oligoglenus Schmarda, 1859: 34, pl. 7 fig. 77 (type locality: South coast of Sri Lanka, Indian Ocean). Stylochus amphibolus Schmarda, 1859: 34, pl. 7, fig. 78 (description). Planocera amphibola – Lang 1884: 444 (description). Paraplanocera oligoglena – Stummer-Traunfels 1933: 3552–3556, figs 123–125 (new combination). — Prudhoe 1985: 109, fig. 90 (identification keys). — Hyman 1953a: 353, figs 118–124 (description and new record from Coronado Islands, Baja California; Punta San Marcial reef, La Paz Bay, Baja California Sur and Miramar Beach, Sonora, Mexico); 1954: 333 (Hilo, Hawaii); 1955a: 75–78, fig. 4c (description and new record from Kwajalein Atoll, South Loi Island, Marshall Islands). — Brusca 1980: 70 (identification keys). — Soutullo et al. 2021: 366–367, fig. 2b–d (description and new record from Carbón Beach, Las Baulas National Marine Park of Guanacaste, Costa Rica). Distribution Pantropical distribution. Sri Lanka, Christmas Island, Quobba Beach, Australia, archipelagos of Polynesia, Micronesia and Melanesia; Hilo, Hawaii, west coast of Japan. On the Mexican Pacific coast, it has been recorded in the Coronado Islands, Baja California; Punta San Marcial reef, La Paz Bay, Baja California Sur and Miramar Beach, Sonora, Mexico; Carbón Beach in Las Baulas National Marine Park of Guanacaste, Costa Rica. Habitat Benthic. Remarks Paraplanocera oligoglena has been recorded from the Indo-West Pacific (Schmarda 1859; Stummer-Traunfels 1933; Hyman 1954, 1955a; Prudhoe 1978; Ken-Ichi et al. 1991). In the Mexican Pacific, P. oligoglena has been recorded from Isla Coronado, Baja California; Punta San Marcial reef, Baja California Sur and Playa Miramar, Sonora (Hyman 1953a; Brusca 1980; Lamothe-Argumedo et al. 1997); it has also been recorded from Carbon Beach, in Las Baulas National Marine Park of Guanacaste, Costa Rica (Soutullo et al. 2021), therefore it is considered a circumtropical species. Paraplanocera oligoglena was described by Schmarda (1859), as Stylochus oligoglenus, Planocera amphibola, Stylochus amphibolus. Later Stummer-Traunfels (1933) made a revision of the specimens described by Schmarda (1859) under these taxa, establishing them as Paraplanocera oligoglena. The species is characterized by an oval body with smooth dorsal coloration brown, cerebral eyes and tentacular eyes, surrounding the base of the nuchal tentacles, and a pharynx with four or five lobes. The male reproductive system features a prostatic vesicle, ducts and paired spermiducal bulbs, accessory prostatic vesicles, a cirrus sac armed with spines and a pair of conspicuous teeth, and a male atrium with a glandular pouch. The female reproductive system features a bulbous vagina, a short female atrium, an elongate oval bursa copulatrix oriented towards the anterior region of the female gonopore, with a thick muscular wall and posteriorly presenting a very scalloped lining, and an elongate Lang’s vesicle oriented towards the anterior region of the female gonopore.