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The problem of automation of data dimensionality reduction for diagnostic model synthesis based on the stationary one-dimensional temporal signals is solved. A set of parameters characterizing the signal properties for automatic object classification is proposed. It allows to significantly reduce the description of the classified objects, to reduce the effect of noise and measurement errors on the classification results, to maintain and enhance the interpretability of synthesized diagnostic models. The practical utility of the proposed transformations for stationary signals in the problem of gas turbine engine blade diagnosis is experimentally confirmed., Решена задача автоматизации сокращения размерности данных для построения диагностических моделей на основе стационарных одномерных сигналов, распределенных во времени. Предложен комплекс показателей, характеризующих свойства сигналов для автоматической классификации объектов, позволяющий существенно сократить описание классифицируемых объектов, уменьшить влияние помех и погрешностей измерений на результаты классификации, сохранить и повысить интерпретабельность синтезируемых диагностических моделей. Экспериментально подтверждена практическая полезность предложенных преобразований для стационарных сигналов в задаче диагностирования лопаток газотурбинных авиадвигателей.

The genus Hemicycliophora (Nematoda: Hemicycliophoridae) contains 132 valid species of plant-parasitic nematodes, collectively known as 'sheath nematodes'. Hemicycliophora spp. are characterized morphologically by a long stylet with rounded basal knobs and a cuticular sheath, present in juvenile and adult stages. Populations of 20 valid and 14 putative species of Hemicycliophora and Loofia from several countries were characterized morphologically using light (LM) and scanning electron microscopy (SEM) and molecularly using the D2-D3 segments of 28S rRNA and internal transcribed spacer (ITS) rRNA gene sequences. LM and SEM observations provided new details on the morphology of these species. PCR-restriction fragment length polymorphisms (PCR-RFLPs) of the D2-D3 of 28S rDNA were proposed for identification of the species. Phylogenetic relationships within populations of 36 species of the genus Hemicycliophora using 102 D2-D3 of 28S rDNA and 97 ITS rRNA gene sequences as inferred from Bayesian analysis are reconstructed and discussed. Ancestral state reconstructions of diagnostic characters (body and stylet length, number of body annuli, shape of vulval lip and tail), using maximum parsimony and Bayesian inference, revealed that none of the traits are individually reliable characters for classifying the studied sheath nematode. The Shimodaira-Hasegawa test rejected the validity of the genus Loofia. This is the most complete phylogenetic analysis of Hemicycliophora species conducted so far. © 2014 The Linnean Society of London.

Root-lesion nematodes of the genus Pratylenchus have a worldwide distribution and are regarded as severe production constraints for numerous important crops. Correct and accurate identification of species within this important genus of plant-parasitic nematodes is critical but is complicated by their stenomorphic status. A polyphasic approach to diagnosis is therefore proposed as a better strategy for distinguishing species and to infer phylogenetic relationships within the genus. Recent studies on Pratylenchus spp. recovered from damaged plantain (Musa spp., genome AAB) in Ghana, West Africa, has resulted in their description as a new species, Pratylenchus speijeri n. sp. Morphological and molecular features of this species were compared with those of P. coffeae, its most closely related species, and other amphimictic species of Pratylenchus that have and undivided face with two lip annuli. Morphological characterisation of P. speijeri n. sp. did not result in an unambiguous separation from P. coffeae, whereas molecular analysis clearly distinguished the two species. Only a few and often variable morphological features, such as larger stylet knobs and a more frequently indented tail terminus separated these populations from P. coffeae. Sequences and phylogenetic analyses of D2--D3 of 28S rDNA and ITS containing regions of 60 individual nematodes from the P. coffeae species complex, sourced from various geographical locations, generated majority consensus BI trees with three major clades, where P. speijeri n. sp. formed its own separate clade from P. coffeae. During recent years the use of SEM, LM and molecular approaches to study P. coffeae, or representatives of the P. coffeae species complex, has resulted in the descriptions of several new cryptic species, namely P. jaehni, P. floridensis, P. parafloridensis and now P. speijeri n. sp. The morphological and molecular features of these cryptic species are compared and the practical application of such molecular data discussed.

Morphologial, biochemical, molecular and karyological analyses of different populations and races of the stem and bulb nematode Ditylenchus dipsaci have suggested that it represents a species complex, of which only D. dipsaci sensu stricto and its morphologically larger variant, known as the giant race of the stem and bulb nematode, are plant parasites of economic importance. The present study singles out the giant race from this complex, herein described as a new species named Ditylenchus gigas n. sp., on the basis of morphological and molecular data obtained from several populations collected from broad beans in southern Italy, southern Spain and Lebanon. The new species epithet, which refers to the large body size of the nematode with respect to the normal races, must be considered to be conspecific with the D. dipsaci ‘giant race’ from Fabaceae in recent literature. Morphologically, the new species is characterized by a body size 1Æ5–2 times longer than the ‘normal race’, stylet delicate (11Æ5–13Æ0 lm long) with knobs distinctly sloping backwards, and long post-vulval uterine sac (81–150 lm long). Results of molecular analysis of rDNA sequences including the ITS1-5.8S-ITS2 region, the D2–D3 fragment of the 28S gene, the small 18S subunit, the partial mitochondrial gene for cytochrome c oxidase I (mtCOI), and hsp90 gene sequences, support the new taxonomic species status for the former D. dipsaci giant race from Vicia faba, and clearly distinguish D. gigas n. sp. from D. dipsaci sensu stricto.

The occurrence of a male-less population of Sphaeronema alni parasitising chestnut (Castanea sativa) roots and inducing a stelar syncytium is reported for the first time in Pola de Somiedo (Oviedo province), Spain.Morphometric and molecular characters of the Spanish population matched those of a topotype population from Russia. SEM observations showed swollen females having the first lip annulus wider than the second and appearing as a cap-like, circumoral elevation. The second-stage juveniles, having a single band in the lateral fields, were characterised by a non-annulated dome-shaped lip region derived from the fusion of the oral disc with all the lip sectors and lip annuli, and showing slit-like amphidial apertures and an oval prestoma. The sequences of the D2-D3 expansion segments of 28S rRNA, partial 18S rRNA and ITS rRNA gene for the Spanish and topotype populations of S. alni were congruent and matched those deposited in GenBank for another population from Germany, thereby confirming their conspecificity. A PCR-RFLP profile of D2-D3 of 28S rRNA for identification of this species was also provided. The phylogenetic relationships between S. alni populations and representatives of the suborder Criconematina, as inferred from analysis of partial 18S rRNA and D2-D3 of 28S gene sequences obtained in this and previous studies, indicated that S. alni formed a basal clade on the majority consensus Bayesian phylogenetic trees, standing together with Meloidoderita sp. or alone. These findings provide additional evidence of the need to clarify the position of Sphaeronema within Criconematina and its relationships with representatives of Tylenchulinae.

Knowledge of rRNA structure is increasingly important to assist phylogenetic analysis through reconstructing optimal alignment, utilizing molecule features as an additional source of data and refining appropriate models of evolution of the molecule. We describe a procedure of optimization for alignment and a new coding method for nucleotide sequence data using secondary structure models of the D2 and D3 expansion fragments of the LSU-rRNA gene reconstructed for fifteen nematode species of the agriculturally important and diverse family Hoplolaimidae, order Tylenchida. Using secondary structure information we converted the original sequence data into twenty-eight symbol codes and submitted the transformed data to maximum parsimony analysis. We also applied the original sequence data set for Bayesian inference. This used the doublet model with sixteen states of nucleotide doublets for the stem region and the standard model of DNA substitution with four nucleotide states for loops and bulges. By this approach, we demonstrate that using structural information for phylogenetic analyses led to trees with lower resolved relationships between clades and likely eliminated some artefactual support for misinterpreted relationships, such as paraphyly of Helicotylenchus or Rotylenchus. This study as well as future phylogenetic analyses is herein supported by the development of an on-line database, NEMrRNA, for rRNA molecules in a structural format for nematodes. We also have developed a new computer program, RNAstat, for calculation of nucleotide statistics designed and proposed for phylogenetic studies.

The suborder Criconematina is a large group of ecto- and endoparasitic nematodes, including several species of major agricultural importance. The D2-D3 expansion segments of the 28S nuclear ribosomal RNA gene were amplified and sequenced from 23 nominal and six unidentified species from the genera Mesocriconema, Criconemoides, Ogma, Criconema, Xenocriconemella, Hemicriconemoides, Hemicycliophora, Paratylenchus, Tylenchulus, Trophonema and Sphaeronema, together with outgroup taxa from Tylenchidae (Aglenchus) and Atylenchidae (Eutylenchus). A sequence alignment optimised using the secondary structure model was analysed using maximum parsimony, maximum likelihood and Bayesian inference approaches under two models. All analyses yielded a similar topology with differences primarily in the position of poorly supported clades. Although some molecular trees differ from the previous morphologically based hypotheses of criconematid phylogeny, maximum likelihood tests did not yield statistically significant differences between some of the tested classical morphological and molecular topologies. DNA data support monophyly for the genera Mesocriconema, Hemicriconemoides and Criconema and reject the hypothesis of a single origin of criconematids with a cuticular sheath or 'double cuticle'. Application of the complex model of rRNA evolution, considering paired nucleotides for the stem and unpaired nucleotides for the loop region, resulted in a majority rule consensus Bayesian tree with unresolved relationships between main clades. This lack of resolution is expected by the low number of independently evolving nucleotides. Sequence divergence in this DNA segment between populations of Mesocriconema xenoplax, M. sphaerocephalum and Hemicriconemoides cocophillus suggest the presence of several sibling species under these taxa names.

Fifteen populations of cyst-forming nematodes belonging to 11 known and one unidentified species collected in countries bordering the Mediterranean Sea were studied using polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP) and internal transcribed spacer (ITS)-rDNA sequences. RFLP profiles generated by the restriction enzymes AluI, AvaI, Bsh1236I, HaeIII, Hin6I, MvaI, PstI and RsaI are presented for Heterodera carotae, H. ciceri, H. fici, H. filipjevi, H. goettingiana, H. hordecalis, H. humuli, H. mediterranea, H. ripae and H. schachtii. Molecular data support the first detection of H. filipjevi from wheat in Italy and H. ripae from nettle in Greece. A relative high level of sequence divergence between populations of H. hordecalis was observed. This suggests that two species might presently be grouped under this taxon. The phylogenetic relationship between the Mediterranean cyst-forming nematode species is analysed based on the ITS-rDNA sequences.