Phaenoplana longipenis

Phaenoplana longipenis (Hyman 1953) Stylochoplana longipenis Hyman, 1953a: 305–307, figs 46–48 (type locality: Playa Miramar, Guaymas, Sonora, Mexico). Stylochoplana longipenis – Brusca 1980: 70, fig. 4.6 (identification keys); 2005: 69 (checklist). Phaenoplana longipenis – Faubel 1983: 104 (new combination). Distribution Point Fermin, San Pedro, California, Santa Catalina Island, Newport Bay, California, United States; Miramar Beach, Sonora, Mexico (southern California to southern Gulf of California). Habitat Benthic and epibiont (found on rocky shores of Miramar beach; as epibionts of Cladophora Kütz. seaweed populations and in the rhizoids of phaeophyte seaweed (kelp)). Remarks Initially, P. longipenis was described by Hyman (1953a) in the genus Stylochoplana. Later, Faubel (1983) proposed the genus Phaenoplana and transferred the species to this genus. The characters Faubel (1983) proposed for the separation of the genera are: a conical penis papilla and a rudimentary oval Lang’s vesicle for Stylochoplana, and a rod-like penis papilla and a horseshoe-like Lang’s vesicle for the genus Phaenoplana. However, P. longipenis presents an elongated cylindrical penis papilla (which by morphology could be considered rod-like) and an elongated oval Lang’s vesicle (different from a horseshoe-like shape). Based on this discrepancies, the present study suggests a complete revision and analysis of the characters that define both genera. Phaenoplana longipenis has an elongated body, with rounded anterior and posterior terminal region, grayish dorsal coloration, cerebral and tentacular eyes present, and a central pharynx oriented slightly towards the anterior region of the body. The male reproductive tract features seminal vesicle and an interpolated prostatic vesicle, the latter with an elongated tubular morphology forming a pronounced V-shaped curvature, and an inert elongated cylindrical penis papilla, structures oriented towards the anterior region of the body. The female reproductive tract has a bulbous vagina, elongated Lang’s duct and a prominent elongated oval an Lang’s vesicle, all oriented towards the posterior region of the body.