A Contribution to the Taxonomy of the Genus Xiphinema Cobb, 1913

In a comparative study of different populations of Xiphinema, the significance of the female gonad structure in species determination is stressed, and monodelphic, pseudomonodelphic, and didelphic forms in the genus are defined. X. chambersi is redescribed and illustrated, X. ensiculiferum and X. krugi are redefined, and X. ensiculiferoides n.sp. and X. orthotenum n.sp. are described. Proposed new synonymies are: X. itanhaense = X. brasiliense; X. bulgariensis and X. conurum = X. italiae; X. ifacolum = X. basiri; X. macrostylum = X. ensiculiferum; X. truncatum = X. elongatum; and X. vulgare = X. setariae. X. yapoense is considered species inquirenda and X. obtusum a nomen dubium. The following eight subgenera of the genus Xiphinema are proposed: Radiphinema n. subg., Krugiphinema n. subg., Xiphinema n. subg., Elongiphinema n. subg., Halliphinema n. subg., Basiphinema n. subg., Rotundiphinema n. subg., and Diversiphinema n. subg. A key to the subgenera of Xiphinema is presented, plus a list of 50 species in the genus, their synonyms, and 10 species inquirendae.