Submitted to: Nematology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/2/2000
Publication Date: 10/1/2000
Citation: Handoo, Z.A., Ibrahim, I.K. 2000. A new species of cyst nematode (heterodera sp.) on panicum coloratum in egypt, with observations on closely related species described on various grasses and rice in florida and louisiana in the united states. Nematology 2:758-759. Interpretive Summary:
Technical Abstract: In 1997, an undescribed cyst nematode (Heterodera sp.) closely related to H. graminophila Golden & Birchfield, 1972 and H. leuceilyma Di Edwardo & Perry, 1964 was found associated with Qasabagrass roots (Panicum coloratum) growing near date palm in Alexandria, Egypt. Soil samples around roots also yielded several juveniles of this species. It differs from H. leuceilyma in having second-stage juveniles (J2) with a shorter stylet (stylet length 23 (22.5-23.5) vs 26 (23-28 micrometers)) and in the shape of J2 stylet knobs, anchor-shaped vs. prominently rounded. The new species differs from H. graminophila in that it has J2 with longer bodies and with longer, more hyaline tail termini than those described from Louisiana and Florida populations: body length 516 (485-550) vs. 430 (380-460 micrometers) in the Louisiana population on barnyard grass (Echinochloa colonum), and 391 (374-412 micrometers) in the Florida population on roots of Panicum rigidulum, hyaline tail terminus 40 (35-43) vs. 32 (25-38 micrometers) in the Louisiana population and 27 (23-31 micrometers) in the Florida population. The new species also has bullae in the cysts, which are absent in H. graminophila. Also, the J2 stylet length in the Florida population of H. graminophila is shorter than that of the new species from Egypt 18.2 (17.6-18.6) vs. 23 (22.5-23.5 micrometers). The male specimens previously reported in H. graminophila and H. leuceilyma were absent in the samples from Egypt. The known distribution in Alexandria, Egypt, is restricted to the original site thus far. Because this species is limited in distribution, its economic importance in rangeland grasses and cultivated crops such as rice is not known.