Bursaphelenchus tiliae sp. n. (Nematoda: Parasitaphelenchidae), a nematode associate of the bark beetle Ernoporus tiliae (Panz.) (Coleoptera: Curculionidae, Scolytinae), in small-leaved lime, Tilia cordata Mill.

Abstract

Bursaphelenchus tiliae sp. n. is described from the bark of dead branches of the small-leaved lime, Tilia cordata, infested with the lime bark beetle, Ernoporus tiliae. The nematode adults and propagative juveniles were present in larval galleries, while dispersal dauer juveniles colonised the Malpighian tubules of adult beetles. Bursaphelenchus tiliae sp. n. is characterised by the body length of 664 (568-817) μm in female and 622 (515-754) μm in male, moderately slender body (a = 41.0 (34.7-47.9) and 43.1 (37.8-51.9) in female and male, respectively), and spicules 20.0 (18.1-21.8) μm long. The extended anterior vulval lip in female, lateral fields with four incisures, long post-uterine sac, and number (7) and arrangement of male caudal papillae, may indicate that B. tiliae sp. n. is closely related to the xylophilus group. It differs from this group by smaller, arcuate spicules with relatively short rostrum, narrow capitulum (5.2-6.9 μm), and indistinct condylus in an almost continuous line with dorsal lamina. Distal third of spicule dorsal contour is usually almost straight. The spicules have a distinct, disk-like cucullus at the terminus. The status of the new species is confirmed by the unique molecular profile of the ITS region (ITS-RFLP) and its close relation to the xylophilus group by DNA sequencing and phylogenetic analysis of the 28S rDNA region. The presence of B. tiliae sp. n. dauer juveniles in Malpighian tubules of their vector bark beetle, E. tiliae, caused limited pathogenicity expressed as a local expansion of the tubule basement membrane and partial degradation of the cellular epithelium.