Two new species of the family Comesomatidae (Nematoda, Chromadorea, Araeolaimida) from the South China Sea

Two new species of free-living marine nematodes found in the South China Sea are described and illustrated. Comesoma gracilis sp. nov . is characterized by very slender body (a = 107.7–111); long, thick cephalic setae up to 28 µm in length; large amphidial fovea with 2.5–3 turns (86%–88% of corresponding body diameter); slender, arcuate spicules 4.5 times cloacal body diameter, with distinct transverse striations and a cephalate capitulum; plate-like gubernaculum without an apophysis; and approximately seven small papilliform precloacal supplements. This species is the only one among all known congeners with a de Man ratio a exceeding 107. Paracomesoma sinica sp. nov . is characterized by its relatively slender body ( a = 123–148); long, thick cephalic setae up to 25 µm in length; spiral amphidial fovea with 2.5 turns; buccal cavity cylindrical with three teeth; slender, arcuate spicules 3.4–3.5 times cloacal body diameter long, with slightly swollen proximal end; plate-like gubernaculum without apophysis; 28–30 papilliform precloacal supplements. The species can be identified from other known species within the genus by a very slender body ( a = 123–148) and relatively shorter spicules (79–84 µm). Comparative tables of main morphometric data of valid Comesoma species and Paracomesoma species are given.