A new marine nematode genus Pseudoplatycoma with a new species from <br />the Sulu Sea and revision of the subfamily Platycominae (Enoplida: Leptosomatidae)

Abstract

The nematode Pseudoplatycoma malaysianis n. gen. n. sp. is described from the Sulu Sea (Malaysia). The new genus is classified in the subfamily Platycominae Platonova 1976. Revision of the new genus and four other genera in Platycominae, resulted in four species from the genus Platycomopsis being transferred to other genera: P. dimorphica and P. mazjatzavi to the genus Platycoma; P. effilata to the genus Micoletzkyia; and P. gibbonensis to the genus Anticoma. Pilosinema is regarded as a asynonym of Platycomopsis and Platycomopsis paracobbi is regarded as a synonym for P. cobbi. A key for identification of the genera and species of Platycominae is presented.

A New Species of Free-living Marine Nematode, <i>Proplatycoma tsukubae</i> sp. nov. (Enoplida: Leptosomatidae), from Japan

“…The genus Proplatycoma differs from all the other genera in Platycominae based on the amphidial apertures with an expanded posterior edge forming a flap-like structure in males and simple elliptical shape in females, in addition to the presence of a pair of accessory structures on ventrolateral side of each spicule and a pair of dorso-caudal apophyses of the gubernaculum (Platonova 1976;Hope 1988a;Chen 2015). Morphologically, Proplatycoma seems to closely resemble Platycoma, which is a monospecific genus with the type species Platycoma cephalata Cobb, 1894 characterized by amphidial apertures with two unique flat setae only in males (Cobb 1894;Platt and Warwick 1983).…”

“…Chen (2015) followed Platonova (1976), distinguishing Proplatycoma and Platycoma based on whether setae or flaps were present. However, according to Chen (2015), whether the setae were "flat" or not was not critical, and he transferred two Platycomopsis species, P. mesjatzevi (Filipjev, 1927) and P. dimorphica Mawson, 1956, to Platycoma because of the several normal setae they possessed, which were located posterior to (not on the posterior edge of) the amphidial apertures (cf. Filipjev 1927;Mawson 1956).…”

“…Chen 2015established Pseudoplatycoma as a monospecific genus based on Pseudoplatycoma malaysianis Chen, 2015. He differed Pseudoplatycoma from Platycomopsis based on the presence of the ocellus-like paired pigment spots throughout the body, and the bluntly rounded proximal end of spicules.…”

“…The taxonomic key for the genera of Platycominae amended from Smol et al (2014) and Chen (2015) is as follows:…”

“…The subfamily Platycominae in the family Leptosomatidae hosts the genera Platycoma Cobb, 1894, Platycomopsis Ditlevsen, 1926(=Dactylonema Filipjev, 1927=Parabarbonema Inglis, 1964=Pilosinema Platonova, 1976, Proplatycoma Platonova, 1976, and Pseudoplatycoma Chen, 2015(Chen 2015. Proplatycoma is a genus of free-living marine nematodes hitherto containing only four valid species.…”