<i>Metachromadora parobscura</i> sp. nov. and <i>Molgolaimus longicaudatus</i> sp. nov. (Nematoda, Desmodoridae) from Mangrove Wetlands of China

Abstract

Two new species of free-living marine nematodes, Metachromadora parobscura sp. nov. and Molgolaimus longicaudatus sp. nov., from mangrove wetlands of Beihai, Guangxi province in China, are described. Metachromadora parobscura sp. nov. is characterized by eight longitudinal rows of somatic setae arranged from the posterior part of the body, loop-shaped amphidial foveae with an open top and double contours, pharynx with bipartite cuticularized internal cavity, spicules with well-developed capitulum, gubernaculum canoe-shaped, without apophysis, 6–8 precloacal tubular supplements, and a short, conical tail with two ventral protuberances. It could be easily distinguished from the known species by spicule length and numbers of precloacal supplements. Molgolaimus longicaudatus sp. nov. is characterized by short cephalic setae, relatively small amphidial fovea, slender spicules ventrally bent with pronounced hooked capitulum and tapered distal end, two poriform precloacal supplements, and a relatively long conico-cylindrical tail. It differs from other species by the shape of spicules and long tail. Nearly full-length SSU sequences (1542–1592 bp) of the two species were provided, and phylogenetic trees based on maximum likelihood analyses supported the taxonomic position of the two new species. The combined use of traditional morphology-based taxonomy and molecular approaches has been proven to be a good choice for identification of free-living nematodes.

Keywords

• free-living marine nematodes
• taxonomy
• Beibu Gulf of the South China Sea
• small subunit (SSU) 18S rDNA