MORPHOLOGY OF FEMALES AND CYSTS OF GLOBODERA-TABACUM TABACUM, G-T-VIRGINIAE, AND G-T-SOLANACEARUM (NEMATA, HETERODERINAE)

Detailed morphological comparisons with light and scanning electron mi croscopy were made of white females and cysts of several isolates of G lobodera tabacum sspp. tabacum (GTT), virginiae (GTV), and solanacearu m (GTS). Observations focused on body shape, anterior region including head shape, lip pattern, stylet morphology, and the terminal area in females; and body shape and terminal area of cysts. The most useful ch aracters to separate the three subspecies were forms of the female bod y, cyst, stylet knobs, tail region, perineal tubercles, anal-fenestral ridge patterns, and the distinctiveness of the anus. GTT is character ized by having round females and cysts, sharply back sloped stylet kno bs, clumped perineal tubercles in the vulval region, tight parallel ri dges in the cyst anal-fenestral region, and a uniformly conoid tail re gion. GTV is characterized by its ovoid to ellipsoid female and cyst s hape, the ''Dutch shoe'' shape of the dorsal stylet knob, the more dis persed perineal tubercles, a maze-like pattern of ridges in the anal-f enestral region, and an indistinct anus. GTS is characterized by its o void to ellipsoid female and cyst shape, moderately backward sloped st ylet knobs, more widely separated ridges, a distinct anus, and a usual ly crescent shaped tail region. Much variability in,shape and patterns is visible among all the isolates of the different subspecies. Tuberc les in the neck, as well as bullae, are reported, and their taxonomic value is discussed.