Females: Variable in size, some giant form reaching 10 cm. Cuticle smooth, head truncate to slightly rounded, lips united, two circles of anterior papillae: six inner labial papillae and four outer cephalic papillae. Amphids small, posterior to labial papillae. Stoma partially collapsed with only an anterior vestibule remaining. Collar lacking, esophageal tissue close to mouth opening, reaching to the base of the vestibule. Cheilorhabdions represented as lightly sclerotized areas lining the inside of the lip region anterior to the esophagus. A small sclerotized area just beneath the cheilorhabdions probably represents the modified prorhabdions. Posterior to these rhabdions, an asymmetrical funnel structure connecting with esophagus lumen at the stoma bottom . Esophagus muscular, the anterior portion of the procorpus slightly expanded just behind the stoma, then extending into a slightly enlarged metacorpus, followed by an isthmus and a basal bulb containing a small valve. Nerve ring surrounding isthmus just anterior to the basal bulb. Excretory pore usually anterior to nerve ring. Lateral fields and phasmids inconspicuous. Gonads amphidelphic, reflexed. Vulva a transverse slit, situated on a protuberance. Vagina short with muscular walls. Tail bluntly conical to dome-shaped with or without a short spine on tip. Second and succeeding generation females in the host are smaller in size. Pigmy forms never found.

Males: Anterior region similar to females. Testis single reflexed. Spicules paired, symmetrical, moderately or slightly curved. Spicule head wider than long (FIG.SEM), ventrally projected. Shaft present. Blade moderately curved, tapering to a point or with bluntly pointed terminus. Velum present. In ventral view, gubernaculum tapering anteriorly to form a short narrow part. Cuneus arrowhead-shaped or Y-shaped. Corpus separated posteriorly. Male tail with 23 genital papillae (11 pairs and a single ventral preanal): 5 pairs subventral preanal, 2 pairs cloacal, one pair lateral and 3 pairs post cloacal. Tail tip with a mucron. Bursa absent.

Measurements (n=25): L=1450 um (1090-1710); W=102 um (77-131); EP=61 um (47-74); NR=110 um (93-124); ES=155 um (136-167); testis reflexion=563 um (400-808); tail=30 um (30.4 um (23.4-39); ABW=42.6 um (32.5-54.6); spicule length=64.6 um (58.5-71.5); spicule width=11.1 um (9.1-13); gubernaculum length=47 um (39-56); gubernaculum width=52 um (3.9-6.5)
(These mearurements are from Poinar, 1967, collected from the strain DD-136)

Infective-juveniles: Much narrower than corresponding parasitic juveniles. Mouth and anal opening closed, esophagus and intestine collapsed; tail pointed; lateral fields distinct.

Measurements (n=55): L=558 um (438-650); W=25 um (20-30); EP=38 um (30-60); NR=85 um (76-99); ES=120 um (103-190); tail=53 um (46-61); a=21 (19-24); b=4.4 (4.0-4.8); c=10 (9.1-11.2); D%=26 (23-28); E%=60 (54-66).

    (These data from Poinar, 1990, in "Entomopathogenic nematodes in biological control" edited by R. Gaugler and H. K Kaya, Bocaraton, FL)

REFERENCES

Nguyen, K. B., and G. C. Smart, Jr. 1992. Steinernema neocurtillis n. sp. (Rhabditida:
 Steinernematidae) and a key to species of the genus Steinernema. Journal of Nematology
 24:463-477.

Poinar, G. O., Jr. 1990. Taxonomy and biology of Steinernematidae and Heterorhabditidae.
Pp. 23-60 in R. Gaugler and H. K. Kaya, eds. Entomopathogenic nematodes in biological
control. CRC Press, Boca Raton, FL.

Poinar, G. O. JR. 1967. Description and taxonomic position of the DD-136 nematode (Steinernematidae: Rhabditoidea) and its retionship to Neoaplectana carpocapsae Weiser.
Proceedings of Helminthological Society of Washington 34:199-209).