Family Heterorhabditidae

Diagnosis

(emended): Rhabditoidea, Rhabditida. Obligate insect parasites. Infective juveniles carrying symbiotic bacteria. Both hermaphroditic and amphimictic females present.

 Hermaphroditic females(FIG.SEM): After entry into an insect host, infective juveniles developing into hermaphroditic females. Head truncate to slightly rounded, six conical lips well developed, separate, each with a terminal papilla; one or two small raised structures sometimes visible at the base of each lip; amphidial opening small. Stoma wide but shallow; cheilorhabdions present, forming a ring, in lateral view resembling two refractile elongate structures. Other parts of the stoma fused to form a collapsed posterior portion. Posterior part of stoma covered by esophagus. Esophagus without metacorpus; isthmus slender; basal bulb swollen; valve in basal bulb reduced. Nerve ring at middle of isthmus. Excretory pore usually posterior to end of esophagus. Vulva slight anterior to mid-body (V%=43-48), slit-like, surrounded by elliptical rings; ovotestis amphidelphic, reflexed. Oviparous, later becoming ovoviviparous. Tail pointed, longer than anal body width, postanal swelling usually present.

 Amphimictic females: Similar to, but usually smaller than, hermaphroditic female; labial papillae prominent. Reproductive system amphidelphic. Vulva not functional for egg deposition, but functional for mating.

 Males: Testis one, reflexed. Spicules paired, separate, slightly curved ventrally. Spicule head short, offset from lamina by a constriction. Gubernaculum usually about half as long as spicule length. Bursa peloderan with nine pairs of genital papillae.

 Infective juveniles: Third-stage infective juvenile usually with sheath (cuticle of second-stage juvenile). Sheath with anterior tessellate pattern and longitudinal ridges; IJ cuticle striated with one smooth band marginated by two ridges in lateral fields. Head with prominent dorsal tooth . Mouth and anus closed. Stoma appearing as a closed chamber with parallel walls. Esophagus and intestine reduced. Excretory pore posterior to nerve ring. Symbiotic bacterial cells found in intestine. Tail pointed.

 Type and only genus: Heterorhabditis Poinar, 1976


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