Submitted to: Journal of Nematology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/7/2010
Publication Date: 9/11/2011
Citation: Carta, L.K., Skantar, A.M., Handoo, Z.A. 2011. Molecular rDNA phylogeny of Telotylenchidae Siddiqi, 1960 and evaluation of tail termini. Journal of Nematology. 42(4):359-369. Interpretive Summary: Nematodes are microscopic soil worms that cause ten billion dollars of crop losses in the United States each year. Stunt nematodes damage a wide range of native and cultivated plants, including alfalfa, legumes, grasses, row crops and ornamentals. Identifying stunt nematodes accurately can be difficult because anatomical features such as tail shape are often similar for distantly related species. To date, molecular analysis of this group has been very limited. In the present study, ARS scientists evaluated unique anatomical features of stunt nematodes and analyzed their molecular genetic information to describe in detail three stunt nematodes, one of which was isolated from plant material intended for import into the United States. The results are significant because they show how anatomical and molecular information can be combined to identify stunt nematode species with greatest consistency. Consequently, scientists, action agencies, and extension agencies engaged in nematode research and control will use this research.
Technical Abstract: Three stunt nematode species, Tylenchorhynchus leviterminalis, T. claytoni and Bitylenchus dubius were characterized with segments of small subunit 18S and large subunit 28S rDNA sequences and placed in molecular phylogenetic context with other taxa of Telotylechidae in GenBank. In 18S trees, the species within the Merliniinae formed a monophyletic group, however there were two to three nested clades of Telotylenchinae taxa in alternative trees. Two putative species of Neodolichorhynchus and two Trophurus species also failed to group together. Distribution of various morphological features including stylet lengths, pharyngeal gland lengths, tail shapes and vulval appendages were characterized for included taxa. Thick-tailed T. leviterminalis from Asia grouped closely with relatively thin-tailed T. claytoni and T. nudus. Bitylenchus dubius clustered with long stylet-bearing Macrotrophurus (Macrotrophurinae) some distance from the other Tylenchorhynchus spp. Conflicting generic and family nomenclature are discussed in light of morphological character distribution.