DESCRIPTION

        Male (first generation). Body ventrally curved, J-shaped or C-shaped when heat--killed. Cuticle smooth under light microscope. Head rounded, offset from the body with distinct labial papillae. SEM face view with six labial and four cephalic papillae. Amphids inconspicuous. Mouth opening usually funnel-shaped with prominent cheilorhabdions. Esophagus muscular with cylindrical procorpus; metacorpus distinct, swollen and non-valvate; isthmus distinct; basal bulb pyriform, valve not observed. Nerve ring sur-rounding isthmus just above basal bulb. Cardia prominent and protruding into intestine lumen. Excretory pore anterior to nerve ring at middle of esophagus. Excretory duct less cuticularized than excretory pore, excretory glands swollen. Monor-chic gonad reflexed. Spicules paired, curved and golden dark yellow in color. Spicule head short about 1/5 of spicule length (SEM1). Velum large. Gubernaculum about 65% of spicule length, boat shaped, swollen at middle, proximal end with knob, ventrally curved. A single ventral precloacal and twelve pairs of genital papillae, seven pairs preanal si-tuated subventrally, and one pair late-rally. Three pairs caudal, subventral and one pair caudal, subdorsal (SEM2). Phasmids inconspicuous. Tail shorter than anal body width with a small mucron  not always observed in permanent mounts.

        Measurements, in micrometers (n=20): L=1674 ±221(1440-2325), W=159±27(120-225), EP=82±9.2(67-99), NR=126±13(109-166), ES=166±15(150-221), testis reflexion=332±50(244-428), tail=32±3.9(27-42), ABW=43±2.6((40-50), spicule length=63±4.4(58-80), gubernaculum length=40±3.1(34-46), D%=49±5.8(42-63), SW=1.5±0.1(1.2-1.6), GS=0.6±0.04(0.5-0.7).

        Female (first generation). Female larger than male. Body robust, spiral shaped or C-shaped when heat-killed. Anterior end rounded, not offset from the body. SEM face view with 6 labial and 4 cephalic papillae. Pore-like amphids located behind lateral labial papillae. Mouth opening cup-shaped to funnel-shaped. Cuticle smooth, lateral field not observed. Excre-tory pore anterior to nerve ring near middle of e-sophagus. Esophagus muscular; procorpus cylin-drical, metacorpus swollen non-valvate, isthmus distinct, basal bulb pyriform, valve not observed. Nerve ring surrounds isthmus or above basal bulb. Cardia prominent and protruding into intestine lumen. Didelphic, amphidelphic gonads, reflexed. Vulva a trans-verse slit at mid-body. Vulva lips pro-truding from the body. Epiptygma absent. Vagina short, straight, with muscular walls. Tail shorter than anal body width with mucron (SEM3). Phasmids inconspicuous.

        Infective juveniles. Body ventrally curved when heat-killed, striated. Sheath (second- stage cuticle) present, sometimes lost. Head nar-row. SEM face view with 4 prominent cephalic papillae. Pore-like amphids anterior to ce-phalic papillae. Mouth and anus closed. Esopha-gus narrows with slender isthmus surrounded by nerve ring. Basal bulb distinct, pyriform, valve not observed. Cardia prominent. Excretory pore ante-rior to middle of esophagus. Hemizonid distinct at isthmus level. Lateral field with eight ridges (at mid-body), submarginal and central pair less distinct (SEM4). Tail elongate, conoid and straight without mucron . Hyaline portion about 39% of tail length. Phas-mids distinct in anterior half of tail.
        Measurements, in micrometers (n=50):L=753±18(704-784), W=35±2.3(30-40), EP=51±1.8(46-54), NR=91±3(78-97), ES=127±3.9(120-138), tail length=81±3(76-89), H%=49±2.6(44-52), ABW=18±0.6(17-19), a=22±1.3(19-25), b=5.9±0.2(5.6-6.3), c=9.3±0.3(8.7-10.2), D%=40±1.7(36-44), E%=62±3.1(56-70).

Type locality. The forest of Xuanmy, Thuongxuan, Thanhhoa province, Vietnam (longitude 105°14'E, latitude 19°57'N, altitude 600 m above sea level). Type host cannot be attributed; the species was isolated using Galleria mellonella as bait. Symbiotic bacterium present has not been identified, and emits a characteristic aroma.
Type material. Holotype male (first generation) and paratypes deposited in the University of Gent, Institute for Zoology, Belgium. Paratype slides with 6 males, 6 females of first generation and 10 infective juveniles deposited in the Department of Nematology, Institute of Ecology and Biological Resources, National Centre for Science and Technology, Nghiado, Caugiay, Hanoi, Vietnam.

Reference
Phan ke, L., N. C. Nguyen, M. Moens. 2001. Steinrnema sangi sp. n. (Rhabditida: Steinernematidae) from Vietnam. Russian Journal of Nematology 9:1-7.