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During a survey conducted on banana plantations in Sistan and Blouchestan province, south-east Iran, a new species of Tylenchulus was extracted from the soil and roots of banana plants. This species, named Tylenchulus musicola sp. n., is characterised by mature females having a swollen, hook-shaped body with a conical and elongate post-vulval portion ending in a round terminus, males having a weak stylet and a cylindrical and thick tail ending in a bluntly rounded and smooth terminus, and by second-stage juveniles having a slender body and a posterior body portion ending in a finely pointed or mucronate terminus. The results of glasshouse host tests indicated that the new species does not parasitise sugarcane ratoons or sour orange seedlings. Tylenchulus musicola sp. n. is distinguished from other known Tylenchulus species by the sequences of D2-D3 expansion segments of 28S rRNA and ITS rRNA genes. Phylogenetic relationships within Tylenchulus were reconstructed based on rRNA gene sequences using Bayesian inference. Diagnostic PCR-ITS-RFLP profiles are presented for T. musicola sp. n., T. furcus, T. graminis, T. palustris, T. semipenetrans and Trophotylenchulus floridensis. PCR with species-specific primers and genus-specific primer are tested and developed for rapid identification of five Tylenchulus species. An identification key to Tylenchulus species is provided. [ABSTRACT FROM AUTHOR]

Tylenchulus graminis n. sp. and T. palustris n. sp. are described and illustrated from broomsedge (Andropogon virginicus L.) and pop ash (Fraxinus caroliniana Mill.), respectively. T. graminis resembles T. furcus in having a distinct anus, but T. graminis second-stage juveniles (J2) do not have a bifid tail. T. semipenetrans does not have a perceptible anus. The mature female of T. graminis has a mucronate pointed terminus while T. semipenetrans has a smooth and round terminus. T. graminis males have wider stylet knobs and basal bulb and a longer tail than T. semipenetrans males. T. graminis J2 have a longer posterior body portion (without large fat globules) than T. semipenetrans J2. T. palustris resembles T. semipenetrans in having an undetectable anus but differs by the short and conoid mature female postvulval section. The male of T. palustris has larger stylet knobs and basal bulb than those of T. semipenetrans and a bluntly rounded tail terminus, which is tapered in T. semipenetrans. T. palustris differs from T. furcus and T. graminis in having an undetectable anus, by the conoid postvulval section of mature females, by the shorter and rounded tail of males, and the shorter J2 posterior body section without large fat globules. T. graminis and T. palustris are parasites of indigenous flora of Florida.

Studies were conducted on the host suitability of four citrus rootstocks--rough lemon (Citrus limon), sour orange (C. aurantium), trifoliate orange (Poncirus trifoliata cv. Argentina), and Swingle citrumelo (C. paradisi x P. trifoliata)--to Tylenchulus graminis which was previously considered a "grass" race of T. semipenetrans. In an uncultivated field, sour orange seedlings grown with T. graminis-infected broomsedge (Andropogon virginicus) were not infected with this nematode after 18-month's exposure to T. graminis population densities ranging from < 0.01 to 0.4 second-stage juveniles (J2)/cm(3) soil. In a greenhouse test, two T. graminis populations from two Florida locations did not infect sour orange seedlings grown for 2 years in soil naturally infested with 0.3 and 1.3 J2/cm(3). Rough lemon, trifoliate orange, and Swingle citrumelo seedlings suppressed T. graminis initial population densities of 7 to final values of < 0.1 J2/cm(3) soil. Final values of > 70.0 J2/cm(3) occurred in soil with broomsedge. These findings provide conclusive evidence that T. graminis is a specific parasite of grasses and does not infect citrus.