Comments On the Taxonomy, Occurrence and Distribution of Longidoridae (Nematoda) in North America

Abstract

The occurrence, distribution and associations with nepoviruses of members of the Longidoridae in North America are presented for each species. Three genera of Longidoridae, Longidorus (10 species), Paralongidorus (2 species), and Xiphinema (38 species) have been reported from North America. Twenty of the Xiphinema species are from the X. americanum group, twelve species have a conoid digitate tail, six species have a hemispherical tail with or without a peg, and two have a long conical tail. Seven North American Xiphinema species have a Z-differentiation and five have only one ovary. One species, X. krugi, has a normal posterior genital branch and ovary and a reduced anterior genital branch lacking an ovary. Longidorus diadecturus differs from all other North American Longidorus species in having weakly developed odontophore flanges and a guide-ring at about mid-odontostyle. Many of the species identifications require to be confirmed, especially those within the X. americanum-group. Five Xiphinema and one Longidorus species are natural vectors of nepoviruses in North America. It is suggested that methods routinely used in North American laboratories for extracting nematodes from soil are inappropriate for recovering Longidoridae and that these nematodes are more widespread and occur more frequently than indicated in published literature.