Two new marine nematode species of the family Chromadoridae collected from coastal zone of North Vietnam sea were described and illustrated are Ptycholaimellus brevisetosus sp. n. and Ptycholaimellus areniculus sp. n The new species P. brevisetosus sp. n. resembles to P. pandispiculatus (Hopper, 1961) but differs from it by the longer body, absence of somatic and cervical setae, more wide labial region, longer cephalic setae and longer spicules, and P. areniculus sp. n. resembles to P. macrodentatus (Timm, 1961) but differs from it by the longer body, relatively shorter cephalic setae, absence of knob-like swellings at base of dorsal tooth in stoma and presence of small piece in spicular apparatus of males. | TẠP CHÍ SINH HỌC, 2012, 34(4): 413-418 TWO NEW SPECIES OF THE GENUS PTYCHOLAIMELLUS COBB, 1920 (NEMATODA: CHROMADORIDAE) FROM COASTAL ZONE OF NORTH VIETNAM SEA Nguyen Vu Thanh1*, Nguyen Dinh Tu1, Vladimir G. Gagarin2, Alekcei V. Tchesunov3, Nguyen Thanh Hien1 1 Institute of Ecology and Biological Resources, VAST, *nvthanh49@ 2 Institute of Inland Water Biology, Russian Academy of Science 3 Moscow State University, Faculty of Biology, Department of Invertebrate Zoology ABSTRACT: Two new marine nematode species of the family Chromadoridae collected from coastal zone of North Vietnam sea were described and illustrated are Ptycholaimellus brevisetosus sp. n. and Ptycholaimellus areniculus sp. n The new species P. brevisetosus sp. n. resembles to P. pandispiculatus (Hopper, 1961) but differs from it by the longer body, absence of somatic and cervical setae, more wide labial region, longer cephalic setae and longer spicules, and P. areniculus sp. n. resembles to P. macrodentatus (Timm, 1961) but differs from it by the longer body, relatively shorter cephalic setae, absence of knob-like swellings at base of dorsal tooth in stoma and presence of small piece in spicular apparatus of males. Keywords: Chromadoridae, Ptycholaimellus, free-living marine nematodes, new species, North Vietnam coastal sea. INTRODUCTION taken with a plastic tube. The fauna of marine nematodes has been studied recently in Vietnam. At present, this investigating field on nematode biodiversity is strongly improved in connection with building up basic biomonitoring data for water quality assessment in watershed and wetland ecosystems along the country’s coatline. This work is revealed as a part of the project funded by Vietnam Academy of Science and Technology (VAST) for study of biodiversity and free-living nematode fauna of the coast of Vietnam. The nematode samples were collected in March 2010 and November 2012. In this paper two new species of the genus Ptycholaimellus Cobb, 1920 .
