Gnesioceros sargassicola Mertens 1832

Gnesioceros sargassicola Mertens, 1832 Fig. 23 A Material examined. Quintana Roo coast, Mexico • 2; Mahahual; 18.6°N, 87.7°W; 7.7 m; 17 Mar. 2018; A. Hernández leg.; CRPPY -0037. Distribution. Currently, Gnesioceros sargassicola is known from Bermuda (Hyman 1939) and Florida to Texas, Gulf of Mexico US coast (Hyman 1954); on Sargassum algae, near the west coast of Africa (Moseley 1877); Boa Vista Island, Cape Verde (Laidlaw 1903); Gaira Bay, Colombia (Quiroga 2008); Curaçao, Bonaire, Little Bonaire, (Netherlands Antilles, Caribbean), Saint Barthelemy, France Antilles; Bahia Fosforescente, Puerto Rico; Marine Biological Station, Virginia Key, Florida, USA; Central Atlantic Ocean, Sargasso Sea (Marcus and Marcus 1968). New record for the coasts of Mahahual, Quintana Roo (Mexican Caribbean). Description. Dorsoventrally flattened body, anteriorly widened with a shallow constriction after the tentacles, undulated body margins, and a blunt-tailed posterior end, 0.8 cm in length and 0.3 cm in width. Yellowish grey background colouration with numerous, rounded, orange or brown spots. Narrow elongated pharyngeal pouch with a central oral opening (Fig. 23 A). Biology. Associated with Sargassum algae.