This paper presents the most common methods for extracting (including Baermann funnel, mistifier, maceration, sieving, elutriation and flotation techniques), processing, examining (handling and fixing) and detecting plant and soil nematodes. Some molecular techniques (e.g. DNA extraction, PCR, sequencing and amplified fragment length polymorphism) available for detection and identification of nematodes are also discussed.

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The evolutionary relationships of 82 species of tylenchid and aphelenchid nematodes were evaluated by use of sequence data of the D2 and D3 expansion fragments of the 28S ribosomal RNA genes. Nine automatic and one culled sequence alignments were analysed using maximum parsimony and Bayesian inference approaches. The molecular data sets showed that the order Tylenchida comprises lineages that largely correspond to two suborders, Hoplolaimina and Criconematina, and other taxonomic divisions as proposed by Siddiqi (2000). Several significant results also derived from our study include: i) the basal position of groups that include entomoparasitic nematodes within tylenchid trees; ii) paraphyly of the superfamily Dolichodoroidea sensu Siddiqi (2000); iii) evidence for a Pratylenchus, Hirschmanniella and Meloidogyne clade; and iv) lack of support for widely held traditional placement of Radopholus within Pratylenchidae and placement of this genus within Hoplolaimidae or Heteroderidae. Congruence and incongruence of molecular phylogeny and traditional classifications and morphological-based hypotheses of phylogeny of tylenchids are discussed.The order Tylenchida Thorne, 1949 includes the largest and most economically important group of plant-parasitic nematodes. As plant parasites they have diverged to exploit all plant parts including foliage, flowers and seeds, but mostly they attack roots. The order also includes mycophagous species, and a large group parasitises the haemocoel of insects and mites. Several classifications and phylogenies have been proposed for ty-

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