Descriptions and Comparative Morphology of Cactodera milleri n. sp. (Nematoda: Heteroderidae) and Cactodera cacti with a Review and Key to the Genus Cactodera.

A new species, Cactodera milleri n. sp., is described and illustrated from specimens obtained from roots of common lambsquarter, Chenopodium album L., from Mattawan, Michigan. Cactodera milleri can be differentiated from other Cactodera species by the presence of punctated egg shells and a second-stage juvenile (J2) stylet length averaging 21.8 mum as measured from freshly killed specimens in water mounts. Thirty-four plant species, including 11 weed species, 18 agronomic crop species, and 5 cactus species were tested as potential hosts of C. milleri. The new species reproduced only on Chenopodium album, C. amaranticolor Cofte. Reyn., and C. quinoa Willd. Cactodera cacti (Filipjev &Schuurmans Stekhoven, 1941) Krall &Krall, 1978, a morphologically similar species, is reexamined. A description of the female and additional morphometric and morphologic data of cysts, males, J2, and eggs are provided for several populations of C. cacti. A review of the morphometrics of all species of Cactodera and a taxonomic key to the seven species are presented.