Two new species of Comesomatidae (Nematoda, Araeolaimida) from the Rizhao coast of the Yellow Sea, China

To study the diversity and taxonomy of marine nematodes on the Rizhao coast, undisturbed sediment samples have been systematically collected since 2022. Two new species of the family Comesomatidae, Comesoma macramphida sp. nov. and Paramesonchium tubulosupplementa sp. nov. are described. Comesoma macramphida sp. nov. is characterized by having the outer labial sensilla setiform, the buccal cavity cup-shaped with a cuticularized projection, the amphidial fovea wide with 2.5 turns, spicules L-shaped with faint striation, the gubernaculum short with a small caudally directed apophysis, 10 or 11 papilliform precloacal supplements, and a conico-cylindrical tail with two long terminal setae.

Paramesonchium tubulosupplementa sp. nov. is characterized by having the cuticle ornamented with transverse punctations and lateral pores, four long cephalic setae, a wide buccal cavity with three ridges, a wide amphidial fovea with 2.5–2.75 turns, spicules curved with a cephalate proximal end, the gubernaculum with a dorso-caudal apophysis, 11 or 12 tubular precloacal supplements, and a conico-cylindrical tail with a short, cylindrical portion.