Submitted to: Nematology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 1/12/2004
Publication Date: 7/2/2004
Citation: Nguyen, K.B., Shapiro Ilan, D.I., Stuart, R.J., James, R.R., Adams, B.J. 2004. Heterorhabditis mexicana n. sp. (heterorhabditidae: rhabditida) from tamaulipas, mexico, and morphological studies of the bursa of heterorhabditis spp. Nematology. 6:231-244. Interpretive Summary: Insect-killing nematodes are small round worms that kill insect pests but don't harm people or the environment. One way of expanding the use of the natural pesticides is to find new species (kinds) of the nematodes that kill pests better than those currently in use. In this study, the discovery and identification of a new nematode species, Heterorhabditis mexicana is described. This new species was found in northern Mexico. It can be differentiated from similar related nematodes based on how it looks (morphology) and its genetic makeup (molecular data). This nematode may offer new potential in controlling insect pests without the use of chemical insecticides.
Technical Abstract: A nematode in the genus Heterorhabditis was found in the northern part of the state of Tamaulipas, Mexico. Morphological and molecular data indicate that this nematode is a new species. The new species is described as Heterorhabditis mexicana n. sp., sister taxon to H. indica. H. mexicana n. sp. is morphologically similar to H. bacteriophora, H. brevicaudis, and H. indica, and can be distinguished from these species mainly by male and female characters. Seventy percent of H. mexicana n. sp. males have 8 pairs of bursal papillae, compared to 9 in all other species. The ratio of the gubernaculum to spicule length (GS ratio) is higher than that of H. bacteriophora, H. brevicaudis, and H. indica, and the length of the spicule relative to anal body width (SW) is lower than all other species. In the ITS region of the rDNA tandem repeating unit, H. mexicana n. sp. has evolved 13 autapomorphic nucleotide character states, differing from its sister taxon H. indica at 113 aligned positions. Our morphological and molecular data are sufficient to identify cladogenesis and delimit H. mexicana n. sp. as evolving independently from the other members of the genus.