Molecular and morphological characterisation of Longidorus polyae sp. n. and L. pisi Edward, Misra & Singh, 1964 (Dorylaimida, Longidoridae) from Bulgaria

Abstract

<i>Longidoruspolyae</i> <b>sp. n</b>., a bisexual nematode species found in the rhizosphere of pear tree (<i>Pyruscommunis</i> 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 (<i>L.arthensis</i>, <i>L.silvae</i>, <i>L.uroshis</i>,), Iran (<i>L.kheirii</i>), and Syria (<i>L.pauli</i>), 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 <i>L.athesinus</i> from Italy and three unidentified <i>Longidorus</i> spp. from USA (<i>Longidorus</i> sp. 1, <i>Longidorus</i> sp. 2, and <i>Longidorus</i> 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 <i>L.pisi</i> from Bulgaria were obtained and variations between populations are discussed.