PROC. BIOL. SOC. WASH. 101(3), 1988, pp. 693-706 A REVIEW OF THE MARINE NEMATODE GENERA PLATYCOMA AND PROPLATYCOMA, WITH A DESCRIPTION OF PROPLATYCOMA FLEURDELIS (ENOPLIDA: LEPTOSOMATIDAE) W. Duane Hope Abstract. —The taxonomic histories of the genera Platycoma Cobb, 1 894 anid Proplatycoma Platonova, 1976 are reviewed. Proplatycoma fleurdelis, n. sp. from Barbados West Indies, is described, and it is the first record of this genus in the western North Atlantic. The structure of the buccal capsule, amphidial flaps, spicula and gubemacula are discussed, and the genera Proplatycoma and Platycoma are redefined. An artificial key to the males of the species of Platyco-ma and Proplatycoma is provided. The genus Platycoma was proposed by Cobb (1894:399) to receive a single new species, P. cephalata and named for the "Two flat hairs of unequal length that grow from the inner margin of the anterior border of each ..." amphid of the males (Cobb 1894:400). Platonova (1976:138) and Piatt & Warwick (1 983: 1 78) have identified these structures as setae. Platycoma africana (Gerlach, 1959) Gerlach, 1962, P. curiosa (Gerlach, 1955) Gerlach, 1962, and P. sud-africana Inglis, 1966 were subsequently added to the genus. Males of species whose descriptions were subsequent to those of the type species lack the pair of "hairs" or "se-tae" emerging from each amphid, but all possess what is presumed to be a modifi-cation of this character. The amphid in males of P. africana is covered by a flap that is broad at its posterior end and tapered an-teriorly to a blunt, central point. The am-phidial flap in males of P. curiosa and P. sudafricana is tapered to form a central, an-teriorly directed lobe, and each has a dorsal and ventral lobe as well. The dorsal and ventral lobes in P. curiosa are highly branched, whereas in P. sudafricana they are not branched, but sloped posteriorly, giving the flap the appearance of an arrow-head. Platonova (1976:139) proposed the genus Proplatycoma to which she transferred P. curiosa, P. africana, and P. sudafricana, with the latter designated as the type species. In the diagnosis of Proplatycoma, Platonova (1976:139) states that the amphids of the males are elongated anteriorly, sometimes with unique processes, and that cuticular, labial outgrowths are absent around the buccal aperture. Although Platonova (1 976: 138) did not give a formal diagnosis for Platycoma, it is stated in her key to the gen-era of Platycominae that there are two flat setae situated near each amphid, and cutic-ular, labial outgrowths are present. Plato-nova (1976:137) also proposed a new subfamily, Platycominae, for the genera Platycoma, Proplatycoma, Platycomopsis and Pilosinema. A collection of marine nematodes from Barbados, West Indies, deposited at the Na-tional Museum of Natural History, Smith-sonian Institution (USNM), contains two males, three females and three juveniles of Proplatycoma fleurdelis, n. sp. These spec-imens most closely resemble those of /*. sud-africana, known only from males. The syn-types of/*, sudafricana were studied for the purpose of making a comparison between members of the two species. The morpho-
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