Descriptions of two new and one known species of Parkellus Jairajpuri, Tahseen and Choi, 2001 (Nematoda: Mononchidae) and their phylogenetic position among Mononchida.

Two new species of Parkellus (Jairajpuri et al., 2001) from Vietnam and a population of Parkellus zschokkei (Ahmad and Jairajpuri, 2010; Menzel, 1913) from Ukraine are described, illustrated and their phylogenetic position among the Mononchida is presented. The molecular data (18S and 28S rDNA) are given for the three investigated species - first time for the genus Parkellus. Parkellus hagiangensis sp. nov. is characterized by a medium-sized buccal cavity, posterior position of the dorsal tooth located below the beginning of the pharynx, males having the ventromedian cuticular pores above and below the excretory pore, short spicules with conical proximal part; females with very faint pars refringens vaginae and small teardrop-shaped pieces, short pars distalis vaginae, the presence of small ventromedian vulval papillae. Parkellus tuyenquangensis sp. nov. is characterized by a medium-sized buccal cavity, posterior position of the dorsal tooth located above the beginning of the pharynx, males having the ventromedian cuticular pores above and below the excretory pore, medium-sized spicules with a cylindrical proximal part, very short lateral guiding pieces, females with very strongly sclerotized pars refringens vaginae, medium size teardrop-shaped pieces, short pars distalis vaginae thickened at the junction with pars refringens vaginae. The newly described species are morphologically most similar to P. parkus and P. zschokkei. An identification key to Parkellus species is presented.

Morphological and molecular characterisation of Tripylina gorganensis from the Slovak Republic as a contribution to the redescription of the species.

Specimens of Tripylina gorganensis, collected from a natural beech forest in Slovak Republic, are described and illustrated. These nematodes were initially identified as an undescribed species, morphologically similar to Tripylina gorganensis described from Iran. An important feature distinguishing both species was the presence of post-vulval uterine sac (PUS) in specimens from Slovak Republic, which, according to the original description (Asghari et al., 2012), was absent in Tripylina gorganensis. However, a careful re-examination of type specimens performed in this study revealed that T. gorganensis also has the post-vulval uterine sac. Consequently, the findings of the morphological and molecular studies performed on the Slovak population and observations on the type material contribute to the redescription of T. gorganensis.

Description of Pratylenchoides ojcowensis sp. nov. (Nematoda: Merlinidae) from Polish Jurassic Highland.

A new species of the genus Pratylenchoides has been described. It was found in Polish Jurassic Highland, in Ojców National Park. Pratylenchoides ojcowensis sp. nov. was isolated from the soil located around tangled roots of Elymus sp. and Trifolium sp. This species is marked by a conical head in both females and males which is not separated from the body contour and has with 4-5 annuli; a relatively short stylet (20.3-21.3 µm females, 17.7-20.9 µm males) with oval knobs directed posteriorly; the dorsal pharyngeal nucleus located anterior to the cardia (the subventral pharyngeal nuclei located posterior; a pharyngeal lobe of length about two body widths (1.8-2.6); a lateral field with 6 lines in the middle part of body and sometimes with partially areolated outer bands; intestinal fasciculi present; round sperm in the spermatheca in females; a female tail with a maximum of 29 annuli, and an annulated tail terminus. The status of the new species has been verifiied by DNA sequencing and phylogenetic analysis of the 28S rDNA region. The results obtained in the study indicated that P. ojcowensis sp. nov. is most related to P. alkani, P. ritteri and P. nevadensis from which is distinguished by the shape of the female head (conoid vs rounded), shorter stylet in females (20.3-21.3 µm vs 22.0-25.0 µm, 21.0-25.0 µm, 22.0-26.0 µm) and differences in 28S rDNA sequences. In addition (as per the original descriptions Yüksel 1977, Sher 1970, Talavera Tobar 1996) it is distinguished from P. alkani by smaller number of male's head annuli (4-5 vs 7-9), from P. ritteri it is distinguished by posteriorly directed stylet knobs (vs directed laterally), from P. nevadensis it is distinguished by oval and posteriorly directed stylet knobs (vs rounded and directed laterally).

How anthropogenic changes may affect soil-borne parasite diversity? Plant-parasitic nematode communities associated with olive trees in Morocco as a case study.

BACKGROUND: Plant-parasitic nematodes (PPN) are major crop pests. On olive (Olea europaea), they significantly contribute to economic losses in the top-ten olive producing countries in the world especially in nurseries and under cropping intensification. The diversity and the structure of PPN communities respond to environmental and anthropogenic forces. The olive tree is a good host plant model to understand the impact of such forces on PPN diversity since it grows according to different modalities (wild, feral and cultivated olives). A wide soil survey was conducted in several olive-growing regions in Morocco. The taxonomical and the functional diversity as well as the structures of PPN communities were described and then compared between non-cultivated (wild and feral forms) and cultivated (traditional and high-density olive cultivation) olives. RESULTS: A high diversity of PPN with the detection of 117 species and 47 genera was revealed. Some taxa were recorded for the first time on olive trees worldwide and new species were also identified. Anthropogenic factors (wild vs cultivated conditions) strongly impacted the PPN diversity and the functional composition of communities because the species richness, the local diversity and the evenness of communities significantly decreased and the abundance of nematodes significantly increased in high-density conditions. Furthermore, these conditions exhibited many more obligate and colonizer PPN and less persister PPN compared to non-cultivated conditions. Taxonomical structures of communities were also impacted: genera such as Xiphinema spp. and Heterodera spp. were dominant in wild olive, whereas harmful taxa such as Meloidogyne spp. were especially enhanced in high-density orchards. CONCLUSIONS: Olive anthropogenic practices reduce the PPN diversity in communities and lead to changes of the community structures with the development of some damaging nematodes. The study underlined the PPN diversity as a relevant indicator to assess community pathogenicity. That could be taken into account in order to design control strategies based on community rearrangements and interactions between species instead of reducing the most pathogenic species.