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United States Department of Agriculture

Agricultural Research Service

Title: A Key and Diagnostic Compendium to the Species of the Genus Tylenchorhynchus Cobb, 1913 (Stunt Nematodes)

Author
item Handoo, Zafar

Submitted to: Journal of Nematology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: September 29, 1999
Publication Date: N/A

Interpretive Summary: Nematodes are microscopic worms that cause eight billion dollars of crop losses in the United states each year. Stunt nematodes are an important group that feed on the roots of many kinds of plants on a world wide basis. They cause damage to field and vegetable crops and other economic plants in the United States. One problem with determining the potential extent of stunt nematode damage to crop plants is that the stunt nematodes present in an area can be identified only with extreme difficulty. Therefore, in the present study specimens or pertinent literature of all described stunt nematode species were examined and evaluated. A new diagnostic aid or identification key of all these species was prepared, and a compendium providing the most important diagnostic characters of each species was developed as a useful supplement to the key. The identification key and compendium are significant because they provide the only accurate, all-inclusive guide to stunt nematode identification. This study will serve as a valuable asset for identifying nematodes and will be used by scientists, action agencies and extension agencies involved in nematode research and control.

Technical Abstract: An identification key covered in four parts for the 107 species of Tylenchorhynchus is given. A compendium providing the most important diagnostic characters for use in identification of species is included as a practical alternative and supplement to the key. Some species in a related but unnecessary genus were placed in the genus Tylenchorhynchus based on morphological structures and logical groupings of the species. Bitylenchus iphilus is transferred to Tylenchorhynchus. Tylenchorhynchus is retained for species with 4 incisures in the lateral field. A list of all the valid species of the genus is given. In this key the main characters useful to separate the species were the stylet length, shape of lip region, number of lip annules, shape of tail and tail terminus, number of tail annules, and position of vulva (V%). However, some of these characters overlapped; other parameters, including body length, number of longitudinal lines, length and shape of spicule and gubernaculum were also useful or were considered for developing a key for identification. The results of this study reveal that the genus currently is composed of 110 valid species.

Last Modified: 7/22/2014
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