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

Abstract

Longidorus polyae sp. n., a bisexual nematode species found in the rhizosphere of pear tree (Pyrus communis 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.