ONE NEW AND 2 KNOWN NEMATODE SPECIES FROM THE SUB-ANTARCTIC ISLANDS-SOUTH GEORGIA AND EAST FALKLAND ISLAND

Populations of three species of nematodes, Pelodera arnbomi n. sp., Pl ectus rhizophilus and Acrobeloides nanus, are described from the Suban tarctic island South Georgia for the first time. Pelodera arnbomi n. s p. differs from all species of Pelodera with a dome-shaped female tail by its conical female tail shape. It differs from P. teres, P. conica and P. incilaria by the number of preanal papillae in the male bursa (2 vs > 2). It is distinguished from P. punctata by a smaller body siz e (880 mu m us 1200-2500 mu m) and smaller c'-value (2.8 vs 4) and fro m P. comandorica by a smaller body size (880 vs 1080-1500 mu m) and la rger c'-value (2.8 vs 1.5) in the females. The relation between some s pecies of Plectus, especially the identity of P. rhizophilus and P. va rians, is discussed. A population of A. nanus from East Falkland Islan d is compared with the South Georgia population and found to differ si gnificantly in many quantitative characters. However, the ranges of me asurements and ratios and also the qualitative characters are overlapp ing between the two populations.