A new root-knot nematode, Meloidogyne silvestris n. sp. (Nematoda: Meloidogynidae), parasitizing European holly in northern Spain.

High infection rates of European holly (Ilex aquifolium) feeder roots by an unknown root-knot nematode were found in a holly forest at Arévalo de la Sierra (Soria province) in northern Spain. Holly trees infected by the root-knot nematode showed some decline and low growth. Infected feeder roots were distorted and showed numerous root galls of large (8–10 mm) to moderate (2–3 mm) size. Morphometry, esterase and malate dehydrogenase electrophoretic phenotypes and phylogenetic trees of sequences within the ribosomal DNA (rDNA) demonstrated that this nematode species differs clearly from other previously described root-knot nematodes. Studies of host-parasite relationships showed a typical susceptible reaction in naturally infected European holly plants, but did not reproduce on a number of cultivated plants, including tomato, grapevine, princess-tree and olive. The species is described here, illustrated and named as Meloidogyne silvestris n. sp. The new root-knot nematode can be morphologically distinguished from other Meloidogyne spp. by: (i) roundish perineal pattern, dorsal arch low, with fine, sinuous cuticle striae, lateral fields faintly visible; (ii) female excretory pore level with stylet knobs, or just anterior to them, EP/ST ratio about 0·8; (iii) second-stage juveniles with hemizonid located 1 to 2 annuli anterior to excretory pore and short, sub-digitate tail; and (iv) males with lateral fields composed of four incisures, with areolated outer bands. Phylogenetic trees derived from maximum parsimony analysis based on 18S, ITS1-5·8S-ITS2 and D2–D3 of 28S rDNA showed that M. silvestris n. sp. can be differentiated from all described root-knot nematode species, and it is clearly separated from other species with resemblance in morphology, such as M. ardenensis, M. dunensis and M. lusitanica.