Parasitic Habits of Trophotylenchulus floridensis (Tylenchulidae) and its Taxonomic Relationship to Tylenchulus semipenetrans and Allied Species.

Parasitism by Trophotylenchulus floridensis Raski, 1957 was studied on roots of sand pine (Pinus clausa [Chapm.] Vasey). Different life stages of the nematode were observed to be covered by dark, spherical, brittle, capsule-like structures which protruded from the root surface. The mature capsule enveloped a single sedentary female with a gelatinous matrix containing an average of 76 (44-117) eggs. The capsule was composed of a single layer of cells which appeared to be of plant origin. The anterior end of the nematode was embedded superficially in the root tissue where it created a feeding site comprised of a small number of discrete stelar parenchyma cells with dense cytoplasm and enlarged nuclei and nucleoli. The nematode also infected slash pine, Pinus elliottii, loblolly pine, P. taeda, red oak, Quercus falcata, post oak, Q. stellada, and sweet gum, Liquidambar styraciflua, in four different locations in central Florida. The taxonomic relationship between Tr. floridensis and Tylenchulus spp. is discussed. Based on differences in the tail and lip regions, position of the excretory pore, type of obesity and especially in the mode of plant parasitism, the genus Trophotylenchulus Raski, 1957 is upheld, and the transfer of Tylenchulus clavicaudatus Colbran, 1966, Ty. rnangenoti Luc, 1957, and Ty. obscurus Colbran, 1961 to Trophotylenchulus is proposed.