H. Taxon; 8 



2. Basic element of pattern of outer layer of cyst wall at middle 

 portion of cyst short zig-zag lines with little or no trace of 

 regular transverse arrangement (figs. 7 and 8) sometimes modi- 

 fied to appear as network (fig. 12) 



Basic element of pattern at outer layer of cyst wall at middle 

 portion of cyst straight or wavy lines (figs. lU and 16) lines 

 at right angles to axis of cyst; sometimes broken by short ob- 

 lique or vertical lines; outer layer of cyst may have grainy 

 appearance (fig. 18) Heterodera cacti group 7. 



Mature cysts with dark bodies (brown knobs) and often sheaf - 

 shaped object (lining of vagina) at posterior end (fig.ll) . 

 On immature cysts, these seldom visible, and then do not appear 

 dark Heterodera schachtii group 8. 



Mature cysts without brown knobs or sheaf-shaped object at 

 posterior end Heterodera giSttingiana group 11 



H. rostochiensis group. Cyst often ovoid, anus located at a 

 transparent spot on cyst so that anal and vulvar openings 

 appear to be about the same size when seen by transmitted 

 light (fig, 21). hyaline portion of larval tail much longer 

 than stylet Heterodera punctata 



Cyst ovoid to globular; anal opening appears much smaller than 



vulva opening (figs. 19 and 20). I^aline portion of larval 



tail about the same length as stylet -5 



5. Larvae very slender; length about 39 times greatest width; 

 orifice of dorsal oesophageal gland about two-thirds stylet 

 length posterior to stylet knobs — Heterodera leptonepia 



Length of larvae about 22 times greatest width; orifice of 

 dorsal oesophageal gland about one-fourth stylet length 

 posterior to stylet 



6. Distance between vulva and anus about one and one- half times 

 diameter of vulva Heterodera rostochiensis 



Distance between anus and vulva about two and one-half times 

 diameter of vulva Heterodera tabacum 



7. H. cacti group. Hyaline portion of larval tail about as lon^ 



as stylet; stylet knobs concave anteriorly 



Heterodera weissi 



Hyaline portion of larval tail usually shorter than stylet; 

 stylet knobs convex anteriorly — Heterodera cacti 



8. H. schachtii group. Cyst always with distinct punctation 

 consisting of dots of uniform size but not in rows (fig. 25); 



