DESCRIPTION
Females: Hermaphroditic females (first generation) with cuticle smooth, lateral lines not observed. In small females lip region with pronounced labial papillae projecting. In large females lip with wide shoulders surrounding stoma. Labial papillae large, resemble flaps that may have a function in foot gathering. Cheilostome as long as wide with thick non- sclerotized walls. Protostome-telostome initially as wide as cheilostom, taping posteriorly, in larger females expanding, becoming wider and shorter, funnel shaped. Oesophagus short in relation to total length narrowing at of nerve ring. Basal bulb pyriform, large as compared to other stages but small in relation to body size, valve distinct. Cardia present. Excretory pore at level of basal bulb. Genital tract paired, reflexed. Uterus and spermatheca located ventrally between vulva and reflex, ovaries located dorsally beyond reflex. Vulva lips protruding. Rectum and anus distinct. Body slightly widening near anus. Tail tapering rapidly over anterior half, especially in large thick females, more slowly over posterior half. Small females usually with slight swelling in posterior half of tails which tend to disappear in larger animals when tail swells, tail tip usually rounded.
Amphimictic females(second generation females> are identical to small first generation females and, differ from large first generation females as follows: typical protruding labial papillae never develop into elaborate flaps; wide shoulders of lip region and wide open, funnel shaped protostome-telostome of large first generation female absent, usually no eggs are laid; no sperm observed; vulva occasionally excreting mucous never observed in first generation females.
Males: As it is assumed that the males do not feed their morphometrics may be of importance. Cuticle smooth, no lateral lines. Lip region and stoma as in pre-adult female. Esophagus more than half body width wide narrowing distinctly at level of nerve ring, basal bulb pyriform with distinct valve. Cardia large. Excretory pore located posterior to level of base of oesophagus. Testis transparent, reflexed, fills body width posteriorly and approximately half body width anteriorly. Spicules slender, paired. Gubernaculum small, single. Tail tapering as in pre-adult male. Tail tip with clear digitate blunt terminus. Bursa enveloping tail, supported by nine pairs of papillae, three preanal, six postanal.
Measurements (n=15): L: 914 (848-1044) micrometers (um); greatest width: 41 (36-45) um; length of esophagus: 118 (110-128) um; length of basal bulb of oesophagus: 23.7 (22-26) um width of basal bulb: 17.5 (16-19) um; body width at level of base of esophagus: 32 (30-34) um; distance from anterior end to excretory pore: 139 (130-150) um; testis length: 656 (562-780) um; spicule length: 51 (48-5-5) um; gubernaculum length: 22.2 (19-25) um; body width at level of anus: 20.7 (18-24) um; length of tail: 35 (30-41) um.
Infective juveniles: As the free-living, infective juveniles do not feed and their internal developments proceeds very slowly, without further growth, the body length and other morphometrics vary little and may be of diagnostic importance. Body slender, tapering regularly from base of esophagus to anterior end and from anal area to tail terminus. Cuticle with large number of longitudinal lines starting short distance behind the head and terminating on tail. Transverse annulation present between lip region and level of excretory pore. Lip region smooth , not set off. Cheilostome narrow rounded in face view, asymmetrically running between thick lips of cephalic region. Protostome-telostome a wider tube of sclerotised, indistinct triangles anteriorly and with continuous cylindrical lining posteriorly. Cephalic region with six papillae, six lips and two amphid. Esophagus long and narrow, with triradiate lumen, 1/3 to 1/4 body width wide, narrowest at level of nerve ring, terminating in valved bulb. Nerve ring distinct, cardia present. Excretory pore and hemizonid obscure. Wide lumen of anterior end of intestine containing bacteria, rest of intestine inactive. Intestine wall dark with globules. Genital primordium obscure. Sphinter muscle between rectum and intestine distinct. Rectum thick walled. Anus distinct. Tail conical with very narrow pointed terminus. Phasmids and deirids not observed.
Measurements (n = 25): L = 685 um (570-740); width = 27 um (22-30); distance of the: rhabdions from the anterior end = 7.6 um (3.5-6.0); rhabdion length = 11.0 um (9.0-12-5); distance of nerve ring from anterior end = 100 um (90-107); distance of hemizonid and excretory pore from anterior end = 112 um (94-123); esophagus length = 140 um ( 135-147); tail length = 102 um (87-119).
DIAGNOSIS: Heterorhabditis zealandica is characterized by body length (685 um), E% (108)and c ratio (6.6) of infective juveniles. Spicule long (51 um) and body width of male are also good identifying characters of this nematode species.
This document was constructed and is maintained by KHUONG
B. NGUYEN
Entomology & Nematology Department
University of Florida