DESCRIPTION
Females: Body and anterior structure similar to those of the species H. bacteriophora . Excretory pore posterior to basal bulb. Gonads amphidelphic, reflexed. Hermaphroditic females (first generation) with ovotestes. Vulva, with protruding lips located near mid-body. Esophagus long, one-half to one-third body width wide. Tail pointed with a postanal swelling. Amphimictic female vulva without protruding lips. Esophagus long and narrow, one-third to one-fourth body width wide. Tail pointed, usually without a postanal swelling.
Males: Anterior region similar to female, but smaller. Testis single, reflexed. Spicules paired, separated, and straight to slightly curved with pointed tips; capitulum usually set off from the shaft; shaft with a dorsal expansion; lamina with single rib. Gubernaculum flat, shorter than half the spicule length, with both the distal and proximal portions folded dorsally. Bursa open , peloderan usually supported by nine pairs of genital papillae with enlarged tips, three pairs anterior to the cloacal opening and six pairs posterior.
Infective juveniles: Third stage juveniles retain second stage cuticles. Cuticle with fine longitudinal striations. Mouth and anus closed. Lips with a large dorsal tooth . Hemizonid distinct, usually located just posterior to the excretory pore. Nerve ring mid-isthmus.
Measurements: All measurements are in micrometers; SE=standard error.
Males: Length = 805.0-1046.5 (942.3 SE 77. 1); greatest width = 48.3-56.4 (50.7 SE 3.6); length of stoma = 3.0-5.0 (3.8 SE 0.5); width of stoma = 4.0-6.0 (5.4 SE 0.8); length of anterior end to nerve ring = 61.4-95.0 (73.7 SE 9-0); length of anterior end to excretory pore = 110.9-168.3 (130.4 SE 29.6); length of anterior end to esophagus base = 99.0-122.8 (115.2 SE 6.1); length of reflexion of testis = 51.5-138.6 (89.1 SE 22.1); length of tail = 23.8-37.6 (31.0 SE 3.1); body width at cloaca = 19.8-27.7 (23.2 SE 2.4); length of spicules = 41.6-49.5 (45.2 SE 3.1); width of spicules = 4.9-6.9 (6.0 SE 0.6); length of gubernaculum = 17.8-21.8(18.6 SE 1.2); width of gubernaculum = 1.9-3.0 (2.2 SE 0.4); ratio GS = 0.36-0.5 (0.41 SE 0.04).
Infective juveniles. Length = 587.7-700.4 (653.7 SE 25.5); greatest width = 24.2-32.2 (27.6 SE 2.7); length of anterior end to nerve ring = 83.2-112.9 (98.5 SE 7.8); length of anterior end to excretory pore = 81.2-112.9 (102.4 SE 7.4); length of anterior end to hemizonid = 99-112.9 (105.6 SE 3.5); length of anterior end to esophagus base = 120.8-138.6 (132.7 SE 4.8); length of tail = 99.0-116.8 (107.2 SE 4.5). Ratio a= 20.5-29.0 (23.9 SE 2.5); b = 4.7-5.4 (4.9 SE 0.2); c = 5.5-6.6 (6.1 SE 0.3); D = 0.6-0.86 (0.77 SE 0.1); E = 0.89-1.1 (0.96 SE 0.08).
Holotype (male). Length = 869.4; greatest width = 56.4; length of stoma = 3.9; width of stoma = 5.9; length of anterior end to nerve ring = 71.3; length of anterior end to excretory pore = 138.6; length of anterior end to esophagus base = 114.8; length of reflexion of testis = 69.3; length of tail = 29.7; body width at cloaca = 27.7; length of spicules = 41.6; width of spicules = 5.9; length of gubernaculum = 19.8; width of gubernaculum = 2.9; ratio GS = 0.47.
Allotype (hermaphroditic female). Length = 4500; greatest width = 225.4; length of stoma = 15.8; width of stoma = 23.8; length of anterior end to nerve ring = 182.2; length of anterior end to excretory pore = 287.1; length of anterior end to esophagus base = 243.5; length of tail = 99.0; body width at anus = 57.4; percentage of vulva = 49.0.
DNA ANALYSIS
RAPD fragments-generated from five decamer oligonucleotides showed
a clear distinction between H. marelata and H. bacteriophora,
H.
megidis, and H. indica, with a minimal RAPD polymorphism frequency
of 0.85 to other Heterorhabditis species examined.
TYPE HOST AND LOCALITY
Unknown in nature; Galleria mellonella larvae used as trap insect in
sandy soil sample; Seaside Beach, Seaside, Oregon.
Liu, J. and R. E. Berry 1996. Heterorhabditis marelatus n. sp. (Rhabditida:
Heterorhabditidae) from Oregon. Journal of
Invertebrate Pathology 67:48-54
TYPE SPECIMENS
Holotype (male) and allotype (hermaphroditic female) deposited in the
United States Department of Agriculture Nematode Collection. Beltsville,
Maryland. Paratype deposited in Nematology Colection, University of California,
Davis, California.
DIAGNOSIS
The males of H. marelata have nine pairs of genital papillae
usually with enlarged tips, which have not been described previously in
members of this genus. H. marelata can be distinguished easily from
H.
megidis and H. indica by length of infective juveniles and the
bursa shape. Shaft of spicule with a dorsal expansion, the ratio GS = 0.41
separate this new species from H. hawaiiensis.
REFERENCE
Liu, J. and R. E. Berry 1996. Heterorhabditis marelatus n. sp.
(Rhabditida:
Heterorhabditidae) from Oregon. Journal of Invertebrate Pathology 67:48-54
This document was constructed and is maintained by KHUONG
B. NGUYEN
Entomology & Nematology Department
University of Florida