Studies on some species of the Xiphinema americanum group (Nematoda, Dorylaimida) occurring in Florida

The study of the morphometrics of putative Xiphinema amevicanum group populations collected in various habitats in Florida, United States of America, revealed the presence of four species: X. citvtcol~mL amberti et Bleve-Zacheo, 1979; X. j7ovidae Larnberti et Bleve -Zacheo, 1979; X. geovgianum Lamberti et Bleve-Zacheo, 1979 and X. Iaevistn'atu??z Lamberti et Bleve-Zacheo, 1979. The relationships of these species with X. amevicanum sensu stvicto and similar species are discussed. It is shown for the first time that X. citn'col~nz and X. laeuistviatum have three juvenile stages. The SOD isozyme iso-electrofocusing patterns also separated the studied populations into four groups; however, it confirmed only partially the morphotypes. The analysis of the ribosomal DNA of seven populations characterized three groups identifying X. flovidae, X. citvicolum and X. laeuistviatum. However, one population morphometrically identified as X. laeuistviatum presented a pattern as X. citvicolum.