Abstract
Longidoruspolyaesp. n., a bisexual nematode species found in the rhizosphere of pear tree (Pyruscommunis L.), is described and characterised using an integrative approach. The new species has a female body length of 6.8–9.1 mm; a comparatively long odontostyle (114.0–127.5 μm); a narrow lip region (14.0–15.5 μm), anteriorly flattened and almost continuous with the body profile; pocket-like amphidial pouches long, deeply bilobed, and slightly asymmetrical, a guide ring at 37–42 μm from the anterior end; normal arrangement of pharyngeal glands; and a short bluntly rounded to hemispherical tail. Four juvenile stages identified: the first stage with a digitate tail, and the second and subsequent stages with a bluntly rounded tail. Males have one adcloacal pair and a row of 10 or 11 single ventromedian supplements; spicules 71.0–74.5 μm long. Based on morphometric data, the new species belongs to a group of species spread over Europe (L.arthensis, L.silvae, L.uroshis,), Iran (L.kheirii), and Syria (L.pauli), which share common characters such as amphidial fovea, lip region and tail shapes, similar odontostyle and body length, and similar first-stage juvenile tail shape. Codes for identifying the new species are A5, B2, C34, D3, E3, F45, G12, H1, I2, J1, K7. The phylogenetic analysis based on D2-D3 expansion domains of the rRNA gene revealed that the new species has the closest relationships with L.athesinus from Italy and three unidentified Longidorus spp. from USA (Longidorus sp. 1, Longidorus sp. 2, and Longidorus sp. 6). New morphometric and molecular data (18S rRNA gene, ITS1-5.8S-ITS2 regions and D2-D3 28S rRNA gene sequences) for three populations of L.pisi from Bulgaria were obtained and variations between populations are discussed.
Highlights
Longidorus Micoletzky, 1922 is the second most diverse genus within family Longidoridae (Thorne, 1935) Meyl, 1961 occurring in all continents except Antarctica
The present study aims to characterise morphologically and molecularly: i) an unknown species of genus Longidorus and ii) populations of L. pisi from Bulgaria, and iii) to evaluate these species’ phylogenetic relationships by using 18S rRNA and D2-D3 expansion domains of the 28S rRNA genes
The Longidorus specimens examined originated from various croplands in Bulgaria: Balgarene village, Petrich, and two vineyards, near Sandanski (Polenitsa village, small-scale management) and Kromidovo village
Summary
Longidorus Micoletzky, 1922 is the second most diverse genus within family Longidoridae (Thorne, 1935) Meyl, 1961 occurring in all continents except Antarctica. Longidorus pisi was originally described from the rhizosphere of Pisum sativum L. growing at the Allahabad Agricultural Institute ( Sam Higginbottom University of Agriculture) in Uttar Pradesh, India (Edward et al 1964). It was subsequently reported from various countries in Asia and Africa. Longidorus latocephalus Lamberti, Choleva & Agostinelli, 1983, a very similar species to L. pisi, was described from southwestern part of Bulgaria where it was associated with various crops. Sequences of D2-D3 28S rRNA or the coxI gene for populations from Greece, South Africa, and Iran have been provided, but, only the last population was characterised with morphological and morphometric data (He et al 2005; Pedram et al 2012; Palomares-Rius et al 2017)
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