Latocestus mexicana

Latocestus mexicana (Hyman, 1953) Alleena mexicana Hyman, 1953a: 275–275, figs 1–3 (type locality: Gulf of California, Mexico). Alleena mexicana – Brusca 1980: 70–71, fig. 4.1 (identification keys); 2005: 69 (checklist). — Lamothe-Argumedo et al. 1997: 15 (new record from El Carrizalillo, Oaxaca, Mexico). Latocestus mexicana – Faubel 1983: 63 (new combination). Distribution Los Ángeles Bay, Willard Island, San Luis Gonzaga Bay, Ángel de la Guarda Island, Puerto Refugio, Baja California; San Ignacio Lagoon, Puerto Loreto (Puerto Escondido); San Carlos, Guaymas, Sonora; Puerto Peñasco, Sonora; Punta Piaxtla, Sinaloa; El Carrizalillo, Oaxaca, Mexico. Habitat Benthic. Remarks Hyman (1953a) described the species as Alleena mexicana. The genus Alleena was established by Marcus (1947) in the family Latocestidae based on the elongated body shape and the perpendicularly oriented male reproductive system. However, Faubel (1983) considered these characters questionable and insufficient to establish the genus; therefore, he assigns Alleena Marcus, 1947 as a synonym of Latocestus. Latocestus mexicana has an elongated body with gray coloration; a band of marginal eyes distributed in the first third of the body; cerebral eyes, scarce tentacular and marginal eyes distributed in a fan shape; elongated and scarcely branched pharynx positioned in the last third of the body, with the oral opening located in the last third of the pharynx, the main intestine occupying two-thirds of the body and is positioned anterior to the pharynx. The male reproductive tract has spermiducal bulbs, and an oval prostatic vesicle lined with digitiform epithelium and positioned directly above the penis papilla, the latter being inert. The female reproductive system has a short female atrium, a tubular vagina, and a thin, elongated Lang’s vesicle.