Steinernema puertoricense

Roman & Figueroa 1994


Female, first generation : Body spiral-shaped when relaxed by gentle heat, cylindroid. Body cuticle smooth. Head truncate to slightly rounded, continuous with body contour. Labial papillae and lips slightly visible in side view, amphids not observed. Stoma short, lined by protorhabdions. Esophagus muscular with nonvalvated metacorpus slightly swollen, isthmus short, basal bulb slightly enlarged and lumen cavity with refractive ridges, cardia present. Nerve ring surrounding isthmus just anterior to basal bulb. Excretory pore usually anterior to nerve ring. Gonads amphidelphic, usually reflexed and filled with eggs that commonly hatch inside the uterus. Vulva a transverse slit protruding from body surface, double-flapped epiptygma present. Vagina short and muscular. Tail usually shorter than anal body width, conical or terminating in a slightly swollen rounded projection.

 Holotype (female, first generation): Length, 7.6 mm; width, 37.5 um; distance from head to excretory pore, 142 um; to nerve ring, 200 um; to esophagus base, 238 um; tail, 45 um; vulva 50%.

 Pigmy-formed females, first generation : Body swollen, C-shaped when relaxed by gentle heat. Resembling female but about two and one half times smaller. Uncommon, observed only in one of the three life cycle studies conducted.

 Female, second generation : Resembling female of first generation but about four times smaller. Body usually C-shaped when relaxed by gentle heat. Tail conical, about two times longer than anal body width.

 Male, first generation : Resembling female. Body C-shaped and curved posteriorly when relaxed by gentle heat. Cuticle smooth. Head truncate to slightly rounded. Gonad single, reflexed. Spicules (FIG.SEM) paired, symmetrical, arcuate, yellow-orange in color. Distal tips of spicules generally lacking ventral concavity or hook, which when present is very indistinct. Gubernaculum long, boat shaped. Under SEM, spicule well curved, slender. Spicule head somewhat longer than wide. Shaft present. Blade arcuate with spicule tip curved ventrally. Velum thin sometimes not observed. In ventral view, gubernaculum tapering anteriorly. Cuneus somewhat Y-shaped reaching end of corpus. Corpus not separated posteriorly. Male tail with about 23 genital papillae (seven pairs ventro lateral, three pairs post anal, one pair dorso lateral, and a single ventral preanal). Terminus rounded. Bursa absent.

Allotype (male, first generation): Length, 1.5 mm; width, 119 um; distance from head to excretory pore, 128 m; to nerve ring, 109 m; to esophagus base, 152 um; tail, 31 um; spicule. 78 um; gubernaculum, 45 um.

 Measurements (n=10): Length=1461micrometers (um), With=101 um (1214-1667), anterior end to excretory pore=123 um (95-143), to nerve ring= 122 um (98-138),esophagus length=159 um (143-178), Tail=34 um (24-43), spicule=78 um (71-88), gubernaculum=40 um (36-45).

Male, second generation : Resembling male of first generation but slightly smaller. Excretory pore anterior to nerve ring.

Juvenile, infective third-stage (IJ): Third-stage juveniles usually enclosed in second stage cuticle. Body narrow and long (more than 1 mm long). Mouth and anus generally closed. Pharynx and intestine usually indistinct. Lateral field composed of six incisures (?). Tail pointed, twice as long as body width.

 Measurements (n=10): Length=1171 micrometers (um)(1057-1238), Width=51 um (47-54), distance from anterior end to excretory pore=95 um (90-102), to nerve ring=117 um (111-121), esophagus length=143 um(138-147), Tail=94 um (88-107), a=23 (20-24), b=8.2 (7.4-8.6), c=12.4 (11.6-13.6), D=0.66 (0.62-0.74), E=1.01 (0.88-108).

Development : The studies conducted demonstrated that S. puertoricense entered larvae of G. mellonella and completed its life cycle in 5 days at 27 to 28 degrees C. It took 2 days for the IJ to enter, killed the host and developed into first generation males and females. Second generation adults appeared 4 days after infection. Infective juveniles began emerging 5 days after infection.

Type locality:Sand from coconut plantation at Loiza, Puerto Rico.

Type specimens:Holotype: First generation female (in glycerin) isolated from sand of coconut plantation at Lofza, P. R. Slide number 1, deposited in the United States Department of Agriculture Nematode Collection (USDANC), Beltsville, Maryland. Allotype: First generation male (in glycerin). Same data as holotype. Slide number 2, deposited in the USDANC, Beltsville, Md. Paratypes: First generation adults and third stage juveniles (in glycerin). Same data as holotype. First generation females, vial number 1; first generation males, vial number 2; thirdstage juveniles, vial number 3; deposited in the USDANC, Beltsville, Md.

Diagnosis : First generation females with large, wide body, males with excretory pore anterior or posterior to nerve ring, spicules lacking a terminal ventral hook, arcuate. Infective third-stage juveniles over 1 mm in length, with smaller esophagus and ratio a value and greater tail length.

Relationships :Steinernema puertoricense can be distinguished from its most closely related species, S. glaseri by the first generation males of S. puertoricense having the excretory pore anterior or posterior to nerve ring, as compared with S. glaseri where the excretory pore is always posterior to the nerve ring. Second generation males have a larger tail: 37 um, range: 33-40 (28 um, range 25-31 for S. glaseri). Steinernema puertoricense males usually lack the hook located at the ventral side of the spicule tip, characteristic of S. glaseri, and spicules are distinctly arcuate. Infective third-stage juveniles have shorter esophagus: 143 um, range 138-147 (162 um, range 158-168 for S. glaseri), greater tail length: 94 um, range 88-107 (78 um, range 62-87 for S. glaseri, and smaller ratio a = 23 (20-24) compared 29 (26=35) for S. glaseri.


 Roman, J. & W. Figueroa, 1994. Steinernema puertoricensis n. sp. (Rhabditida: Steinernematidae), a new entomopathogenic nematode from Puerto Rico. Journal of Agriculture, University of Puerto Rico 78:167-175.

This document was constructed and is maintained by KHUONG B. NGUYEN
Entomology & Nematology Department
University of Florida