Armatoplana panamensis

Armatoplana panamensis (Plehn, 1896) Leptoplana panamensis Plehn, 1896: 151–153, pl. 10 figs 3–5, 10–11, pl. 13 fig. 11 (type locality: Gulf of Panama). Stylochoplana panamensis – Laidlaw 1903: 308 (new combination). — Bock 1913: 179 (description). — Hyman 1953a: 301–304, figs 39–41 (new record from Santa Barbara Island, Catalina Island, Newport Harbor, California; Guaymas, Sonora, Mexico). — Brusca 1980: 70, fig. 4.6 (new record from Gulf of California, identification keys); 2005: 69 (checklist). Distribution Southern California to southern Gulf of Panama. Santa Barbara Island, Catalina Island, Newport Harbor, California; Guaymas, Sonora, Mexico and Gulf of Panama. Habitat Benthic and fouling (rocks, sandy bottom at 73.152 m depth off Santa Catalina Island and on floating pilings and buoys in Newport Harbor, California). Remarks Plehn (1896) described the species, whose type locality is the Gulf of Panama. Later, Hyman (1953a) recorded it in California and Guaymas, Sonora, Mexico. Hyman (1953a) observed morphological and size variations in the seminal vesicle, prostatic vesicle, and the distance between the ejaculatory duct and the seminal vesicle; however, she determined these differences as a possible intraspecific variation and assigned the specimens to A. panamensis based on the arrangement and distribution of the eyes, the presence of a long-curved stipe, and an elongated Lang’s vesicle, described in the nominal species. The present study, based on the revision and comparison of the diagnoses and schemes made by Plehn (1896) and Hyman (1953a), found a difference in the coloration pattern of the species. Plehn (1986) described a dark grayish-brown coloration with a pattern composed of three dark longitudinal lines (Plehn 1986: figs 3, 10–11). This pattern was not observed or described in the specimens of Hyman (1953a), who mentions a grayish dorsal coloration. In addition to the morphological variations previously determined by Hyman (1953a), we suggest an exhaustive review of the material described by both authors.