Morphological and Molecular Diversity among Pin Nematodes of the Genus Paratylenchus (Nematoda: Paratylenchidae) from Florida and Other Localities and Molecular Phylogeny of the Genus.

Pin nematodes ( spp.) are root parasites found worldwide. They have different life cycles and feeding habits and can damage a wide range of plants. A remarkable diversity of pin nematode species was found in soil samples from Florida and other states of the USA, Canada, and Spain. Using integrative taxonomy, two new species ( sp. n. and sp. n.), six valid species (, , , , (= syn. n.), and ), and two undescribed species were identified from Florida; , , , , and were found in California, in Hawaii, in Oregon and Washington, and one new species, sp. n., in Alaska. Outside the USA, was detected in samples from Canada and Spain as well as and sp. from Spain. The pin nematode species from Belgium and Russia identified in former studies as sp. F was herein described as a new species with the name of sp. n., using a population from Alaska. Previously reported molecular type A of from Hawaii was reclassified as sp. n., using a population from Florida. sp. n. from Florida has obese sedentary females with a stylet 63-71 µm long. The results of the molecular analysis of from Florida and China indicated that it was conspecific with from Hawaii and considered here as its junior synonym. New 26 D2-D3 expansion segments of 28S rRNA, 17 ITS rRNA, and 20 gene sequences were obtained in this study. Phylogenetic relationships of are reconstructed using the D2-D3 of 28S rRNA, ITS rRNA, and gene sequences. Congruence of molecular and morphological evolution and species identification problems are discussed. Obese females were found in two major clades of . The problem of reference materials is discussed, and it is proposed to make more efforts to collect topotype materials of known species for molecular study.