Criconematina (nematoda: tylenchida) from the aleutian islands.

A new genus (Cerchnotocriconenta) and three new species (C. psephinum, Hemicycliophora amchitkaensis, and Paratylenchns amundseni) are described from Adak and Amchitka Islands in the Aleutian chain. The new genus differs from all other criconematid genera in having irregular, convex sculpturing consisting of small, oval plates on the anterior and posterior regions of each annule, with the mid-annular region minutely punctate or dentate. H. arnchitkaensis n. sp. resembles H. similis Thorne and H. zuckermani Brzeski, but has only one head annule, instead of two. P. antundseni n. sp., which has a stylet 17-19 mum long, is similar to P. tateae Wu &Townshend and P. labiosus Anderson &Kimpinski, but differs by the presence of males and the possession of conoid-truncate lip region, functional spermatheca, and long male tail (c = 8.5-9.5). Seriespinula seymouri Wu (Mehta &Raski), Nothocrieonema longulum (Gunhold) De Grisse &Loof, and Macroposthonia xenoplax (Raski) De Grisse &Loof are also reported from the islands.