Steinernema thanhi
Phan, Nguyen & Moens, 2001

KHUONG B. NGUYEN
Entomology & Nematology Department
University of Florida

DESCRIPTION

       Male (first generation). Body curved ventrally or J-shaped when heat-killed. Cuticle smooth. Head rounded and offset from the body. SEM face view with six prominent labial papil-lae and four cephalic papillae. Amphids pore-like below labial papillae. Mouth opening fun-nel-shaped or cup-shaped. Esophagus with cylindrical pro-corpus; metacorpus slightly swollen non-valvate. Isthmus indistinct; basal bulb pyriform, valve not observed. Nerve ring usually surrounding isthmus or situated above basal bulb. Excretory pore between nerve ring and middle of pharynx. Excretory duct cuticularized and excretory gland swollen. Monorchic gonad reflexed. Spicule paired. yellow-brownish in color and ventrally curved; spicule head (manubrium) longer than wide (SEM1) . Velum thin. Gubernaculum boat-shaped, swollen at middle and proximal end with knob, ventrally curved. A single ventral precloacal papilla and 13 pairs of genital papillae present and arranged as follows: six pairs subventral, preanal and two pairs lat-eral at the same level of the first and second subven-tral preanal papillae; one pair postanal subven-tral close to the cloacal opening and one pair lateral at the same level; two pairs caudal (SEM2), subventral close to the tail terminus and one pair caudal, subdorsal. Tail shorter than anal body width and without macron. Phasmids in-conspicuous.
        Measurements, in micrometers (n=20): L=1591±93(5370-9180) , W=97±15(76-124), EP=144±9(129-163), NR=167±11(134-182), ES=198±(10(182-214), testis reflexion=263±57(178-396), tail length=29±3(24-35), ABW=41±5(34-48), spicule length=72±3(67-78), gubernaculum length=49±4(40-56), D%=73±4(64-82), SW=1.8±0.2(1.5-2.1), GS=0.7±0.1(0.5-0.8).

        Female (first generation). Body robust, spiral-shaped or C-shape when heat-killed. Cuticle smooth under light microscope. Head rounded, offset from the body. SEM face view with six prominent labial and four cephalic papillae. Mouth open-ing tunnel-shaped or cup-shaped. Stoma shallow. Esophagus with cylindrical procorpus; metacorpus slightly swollen without valve. Isthmus indistinct. basal bulb pyriform and valve not observed. Nerve ring surrounding isthmus or sit-uated above basal bulb. Excretory duct cuticu-larized and excretory gland swollen. Excretory pore be-tween nerve ring and middle of esophagus. Cardia prominent. Didelphic, amphidelphic gonad reflexed and tightly filled with eggs. Vulva transverse slit on a protuberance without epiptygma. Vagina short and oblique. Tail usually shorter than anal body width with terminal peg (SEM3).

Infective juveniles.Often enclosed  in the cuticle of second-stage. Bodyusually straight or sIightly curved  when  heat-killed. Head smooth rounded. slightly offset from the head. On SEM face view, labial papillae not observed; four cephalic papillae prominent; amlphid pore-like, post-labial but anterior to cephalic papillae. Mouth and anus, closed.  Esophagus long and narrow, isthmus distinct with surrounding nerve ring; basal bulb elongate. Valve not observed. Cardia prominent. Excretory pore bet-ween nerve ring and middle of esophagus. At mid-body, lateral field with eight ridges (nine incisures)(SEM4) . Hyaline portion about 40%i of tail length . Tail conoid without mucron . Phasmids distinct and, located in anterior half of tail.
    Measurements, in micrometers (n=20): L=851±(720-960), W=31±3(27-39), EP=75±4(68-84), NR=96±6(83-112), ES=129±6(115-146), H%=40±4(33-46), ABW=21±2(18-24), a=27±2(23-33), b=7±1(6-8), c=14±1(12-16), D%=58±4(52-67), E%=119±8(101-138).

    Type host: unknown
    Type locality: sandy soil of a garden near the sea beach in Haithanh, Tinhgia, Thanhhoa, Vietnam.
    Type specimens: Holotype: Gent University, Institute of Zoology, K.L. Ledeganckstraat 35, 9000, Belgium.

Reference

Phan, K. L, N. C. Nguyen, and M. Moens, 2001.Steinernema loci sp. n. and Steinernema thanhi sp. n. (Rhabditida:Steinernematidae) from Vietnam. Nematology 3:503-514.