The systematic position of Pratylenchoides ritteri Sher with observations on its embryogenic development

Abstract

Sher (1970) described Pratylenchoides ritteri from soil around an unknown grass and weeds collected near Cap Antibes, France. At that time he differentiated the genus Pratylenchoides Winslow from the genus Radopholus Thorne by the presence of deirids, oesophagus overlapping the intestine ventrally and dorsally « with at least one oesophageal gland nucleus above the oesophageal intestinal valve », less sexual dimorphism, and the gubernaculum not projecting from the body. Seinhorst (1971) separated Pratylenchoides from the genus Radopholus by the arrangement of the oesophageal glands. He included the former in the generic group with asymmetrical oesophagus (the oesophageal lumen is shifted laterally and situated between the dorsal and the shorter subventral gland) and the latter in the generic group with symmetrical oesophagus (the oesophageal lumen is ventrally shifted and situated between the subventral glands). In this paper we discuss the systematic position of P. ritteri according to the diagnosis of Sher and Seinhorst, report on the embriogenesis and biology of this species, and describe a case of intersexuality.