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Root-knot nematodes (Meloidogyne spp.) are among the biotic factors that limit tomato production worldwide. The objectives of this study were to assess the distribution and identify Meloidogyne spp. and associated problems from major tomato growing areas of Ethiopia. A total of 212-rhizosphere soil and 123 root samples were sampled from 40 localities during 2012/13 growing season. A total of 646 respondents participated in the questionnaire to assess knowledge and practice of farmers and factors associated with RKN damage on tomato. Out of the 212 soil samples collected, 47.2% were found infested by various Meloidogyne species 8 weeks after the start of the bioassay test. Out of the 123 root samples collected, 65% had root galls. The highest prevalence (100%) of RKN was found on samples collected from Adami Tullu, Babile, Erer Gota, Hurso, Jittu, Tikur Wuha, Tepo Choronke, Zeway and Koka. The highest incidence (100%) of RKN was found from Adami Tullu, Jara Weyo, Babile, Erer Gota, Hurso, Jittu, Tikur Wuha, Tony farm, Tepo Choronke, Zeway and Koka localities based on direct observation of galls on collected root samples. Out of the 646 respondents, 43.3% reported to have RKN damage symptoms when shown the symptoms while 56.7% of them did not report damage. The highest significant effect on the dependent variable RKN damage on tomato roots comes from the previous crop, soil texture, awareness about RKN and source of irrigation water used. The presence of Meloidogyne incognita, M. javanica, M. arenaria and M. hapla on tomato was confirmed using a combination of molecular and biochemical identification tools. Five isolates of Meloidogyne spp. were not properly identified and could be new species. The two tropical species, M. incognita (48.4%) and M. javanica (41.2%) were the most prevalent species. Both species were also co-infesting tomato plants. Meloidogyne hapla was detected for the first time in an open tomato production farmer’s field at ‘Zeway’ locality with 1620 m.a.s.l. elevation. The occurrence of these Meloidogyne species alone, or in mixed populations from samples collected, clearly shows that RKN are widespread in major tomato growing areas of Ethiopia. In the near future, the economic importance of M. arenaria and M. hapla on tomato production in Ethiopian agriculture should be investigated.

Summary Pratylenchus rwandae n. sp., a root-lesion nematode associated with maize (Zea mays) from Rwanda, is described. This new species is characterised by females of medium to large size (469-600 μm) having an offset lip region with three annuli, stylet of 13-14.6 μm long with prominent rounded or anteriorly concave knobs, short to long pharyngeal gland overlap of 10.9-34.7 μm long, variable number of lateral lines (4-14) in different regions of the body, lateral field consisting of smooth bands, oval to slightly rounded spermatheca, vulva located at 75-80% of the total body length, post-vulval uterine sac (PUS) 20.3-26.5 μm long, tail subcylindrical to conoid with variation in tail tip shape from rounded to truncate or indented with generally smooth tip, and male unknown. The results of the phylogenetic analyses based on sequences of the D2-D3 expansion regions of 28S, partial 18S and ITS of rDNA and COI of mitochondrial DNA indicate that P. rwandae n. sp. is a species within the Penetrans group and appears as a sister species to a group comprising P. convallariae, P. dunensis, P. fallax, P. oleae, P. penetrans, P. pinguicaudatus, and three other unidentified species. A comparison of important morphological characters of the closely related Pratylenchus spp. is provided.

Comprehensive morphological and molecular analyses revealed that published ITS sequences of the economically important plant-parasitic nematodePratylenchus goodeyiare actually sequences from distantly free-living bacterivorous ‘cephalobids’. We demonstrated that this incorrect labelling resulted in a cascade of erroneous interpretations, as shown by the reports of ‘P. goodeyi’ on banana in China and on cotton in India. This clearly illustrates the risk of mislabelled sequences in public databases. Other mislabelledPratylenchuscases are discussed to illustrate that this is not an isolated case. Herein,P. lentisn. syn. is considered a junior synonym ofP. pratensiswhileP. flakkensiswas for the first time linked to DNA sequences using topotype material. As taxonomic expertise is decreasing and sequence-based identification is growing rapidly, the highlighted problem may yet increase and a strong link between morphology and DNA sequences will be of crucial importance in order to prevent, or at least minimise, sequence-based misidentifications.

Amphimictic populations of root-lesion nematodes with numerous males and females having three lip annuli, a functional spermatheca and non-areolated lateral field occur on sword fern (Nephrolepis exaltata) in Florida. Identified for decades asPratylenchus penetrans, they appeared to be a morphologically separated species on the basis of a longer stylet (17.8-18.3 μm) thanP. penetrans(15-17 μm) and different lip pattern inen faceview (rectangularvsdumb-bell inP. penetrans). Morphologically similar amphimictic root-lesion nematodes have also been detected on flax lily in Costa Rica. Subsequent morphological observations indicated that these amphimictic root-lesion nematodes from fern and flax lily are closely related to the parthenogenetic speciesP. bolivianus, which has areolated lateral fields. In spite of the reproductive and morphological dissimilarities between these populations, their separation into different species was not supported by the results of molecular analyses of their DNA sequences. The populations used in these analyses included those that are amphimictic from Florida and Costa Rica and others that are parthenogenetic from the type locality in Bolivia, and geographically distant localities in Chile, China, Colombia and Europe. Phylogenetic analyses of the ITS and D2-D3 expansion segments of the 28S rRNA gene indicated that they belong to the same species,P. bolivianus, which consists of two morphotypes,P. bolivianus(am) amphimictic andP. bolivianus(pm) parthenogenetic, herein described and illustrated. Contradictory results were obtained by the analyses using a portion of thehsp90gene. The phylogenetic study, which included sequences of other root-lesion nematodes, a topotype and geographical distant populations ofP. zeae, revealed thatP. bolivianusandP. zeaeformed highly supported clades in the majority consensus trees. PCR with species-specific primers for rapid diagnostics ofP. bolivianusandP. zeaewere developed and tested.