On the nematode genus Heterodorus Altherr, 1952 (Dorylaimida: Nordiidae) with descriptions of three new species

The genus Heterodorus Altherr, 1952 is analysed and redefined. Of the nominal species, four are synonymized,namely H. magnificus Altherr, 1952 and H. thornei (Baqri & Jairajpuri, 1974) with H. arcuatus (Thorne, 1939), H. bongersi(Mushtaq, Baniyamuddin & Ahmad, 2007) with H. brevidentatus (Thorne, 1939) and H. satendri (Baqri & Jairajpuri, 1974) withH. constrictus (Jairajpuri & Loof, 1968). Three species, new to science, are described. Heterodorus unicus sp. n. from PapuaNew Guinea is distinguished by its small body (on average 1.23 mm), continuous lip region, short odontostyle as long as lipregion width, far posteriorly located D nucleus, greenish intestine, deep vulva, and by a single ventromedial supplement.Heterodorus monticola sp. n. from Peru is characterized by its short body (on average 1.36 mm), continuous lip region, shortodontostyle as long as 1.1–1.2 lip region widths, far posteriorly widened pharynx, strongly swollen vagina, and by two or threeventromedial supplements. Heterodorus alius sp. n. from Papua New Guinea also belonging to the small species (on average 1.22mm long) shows some atypical or marginal characters: a longer cylindrus, more anteriorly located D nucleus (54–57 %), moreanteriorly posited vulva (39–41 %), longer vagina, longer spicula, and a row of six or seven ventromedial supplements beginningcloser to the adanal pair as usual. A key to the identification of Heterodorus species is added. Finally, an Enchodelus species istransferred to Papuadorus Andrássy, 2009 as P. coomansi (Nicholas & Stewart, 1985) comb. n.