Cactodera weissi
Steiner, 1949
Photo Gallery- Nebraska nursery
FEMALES (20):  Length (including neck) 408-688 um (503, SD 76); width 201-408 um 278, SD 65); L/W ratio = 1.4 -2.3 (1.4, SD 1.9); stylet 21.8 - 24.3 um (22.8, SD 0.53); dorsal esophageal gland orifice 4.5 - 5.6 um (5.2, SD 0.34) from base of stylet.
Hololectotype (female): Length 605 um; width 405 um; L/W ratio = 1.5; stylet 22.6 um; dorsal esophageal gland orifice 5.2 um form base of stylet.
Description:  Body pearly-white, basically lemon-shaped, with protruding neck and vulva.  Cuticle about 12 um thick; randomly arranged punctation on surface, often giving granular appearance and sometimes obscuring external cuticular pattern, which is essentially as described for the cysts.  Head (bearing two annules, the second being larger) set off from body.  Stylet rather delicate with small distinct knobs sloping posteriorly.  Esophageal glands and excretory pore commonly located at base of neck as illustrated.  Vulva distinct, with slit measuring 13 - 20 um (15, SD 1.9).  Anus small, inconspicuous, located about 10% of body length from posterior end.

CYSTS (20):  Length (including neck) 385 - 750 um (598, SD 87); width 230 - 460 um (350, SD 68); L/W ratio =  1.2 - 2.3 (1.7, SD 0.3); diameter of fenestra (on longest axis) 29 - 38 (34, SD 2.8).
Description:  Cysts abullate, circumfenestrate, light brown to brown in color, basically lemon-shaped, and with protruding neck and vulva.  Excretory pore situated near base of neck.  Vulval denticles about 16 - 20 um below fenestral surface and measure approximately 6 - 11 um in length and 3 - 5 um in width at their base.  Vulval denticles might occur singly at random, in small clusters, as a partial ring, or ocasionally as a complete ring.  External cyst wall pattern at midbody consists of basically straight to wavy lines extending around the cysts at right angles to the long axis of the cyst and commonly broken by short oblique or vertical lines.  Rather fine punctation, arranged randomly, often present on cyst wall.  Anus distinct though small, without a surrounding pattern; located about 10% of cyst length from posterior end.

MALES (20):  Length 943 - 1240 um (1034, SD 69); a = 27 - 33 (31, SD 2.1); b = 5.1 - 6.7 (6.0, SD 0.9); dorsal esophageal gland orifice 4.5 - 5.6 um (4.8, SD 0.4) from base of stylet; spicules 30.8 - 33.6 um (32.4, SD 0.5); tail length 1.1 - 2.8 um (1.6, SD 0.5).
Allolectotype (male): Length 1040 um; a = 32; b = 5.6; c = 928; stylet = 24.6 um; body width 31 um.
Description:  Body cylindrical, elongate, and tapering gradually at each end.  Head offset, bearing 5-6 annules.  Cuticular annulation distinct, annules approximately 1.8 um wide; subcuticle with annules about one-half this size but twice as numerous.  Lateral field 5.6 - 6.2 um (5.7) in width, consisting of 4 incisures forming 3 bands of equal width on most of body and not areolated except in extreme anterior portion.  Mid-body width measures 29 - 36 um (33, SD 2.1).  Cephalic framework heavily sclerotized; stylet strong with rather rounded, prominent knobs.  Center of median bulb 45 - 60 um (51, SD 3.4) from anterior end.  Hemizonid small but distinct, usually located 5 -6 annules anterior to excretory pore;  hemizonion smaller, about 10 annules posterior to excretory pore.  Esophageal region appearing about as illustrated.  Testis one.  Spicules arcuate, singly notched at tips.  Tail extremely short, somewhat variable in shape.  Small phasmids near tail terminus.

SECOND-STAGE LARVAE (20):  Length 372 - 420 um (407, SD 12); a = 18 - 22 (20, SD 0.9); b = 2.3 - 3.5 (2.6, SD 0.1); c =  8.4 - 9.5 (8.9, SD 0.3); stylet 19.6 - 21.8 um (20.4, SD 0.5); dorsal esophageal gland orifice 4.5 - 5.6 um (5.3, SD 1.9); hyaline tail terminal 17 - 24 um (20.2, SD 1.9); caudal ratio A = 3.0 - 3.9 (3.5, SD 0.3); caudal ratio B = 6.6 - 10.5 (8.4, SD 1.2).
Description:   Body cylindrical, elongate, tapering especially to posterior end.  Head, bearing 5 indistinct annules, offset from body.  Cuticular annulation of body distinct, annules measuring about 1.4 um at mid-body; subcuticular annules less distinct and twice as numerous.  Lateral field without areolation except anteriorly; composed of 3 incisures and averages 3.5 um in width at mid-body.  Cephalic framework heavily sclerotized. Stylet strong, with prominent knobs concave on anterior surface.  Center of median bulb 35 - 42 um (38, SD 1.6) from anterior end.  Hemizonid prominent, located anterior and adjacent to excretory pore;  hemizonion usually about 8 - 10 annules posterior to the latter.  General esophageal region commonly appearing as illustrated. Tail tapering to a fine, rounded terminus, with annulation continuing to terminus, sometimes giving a bead-like effect.  Phasmids small, indistinct; located in center of lateral field about midway on tail.

EGGS (20) (Larvae within):  Length 96 - 106 um (101, SD 2.9); width 40 - 44 um (42, SD 0.8); L/W ratio = 2.3 - 2.6 (2.4, SD 0.09).  Egg shells hyaline, without visible markings, as seen with both an optical microscope and a scanning electron microscope.

TYPE HOST AND LOCALITY (designated by original author):  Roots of knot-weed, Polygonum pensylvanicum L., growing near the steam plant at Plant Industry Station (now Beltsville Agricultural Research Center-West), Beltsville, Maryland.

DIAGNOSIS:  Heterodera weissi is most closely related to H. amaranthi but differs mainly in having a longer larval tail and tail terminal (46 um and 20 um vs 35 um and 15 um, respectively, for H. amaranthi).  Though of an indefinite nature, the cysts of H. weissi are lighter in color than those of H. amaranthi which are commonly dark brown to almost black.  Hyaline egg shells without punctation and larval stylet knobs with concave anterior surface distinguish H. weissi from H. cacti which have heavily punctate egg shells and convex stylet knobs in larvae.

(Description- Golden & Raski, 1977)