Description of a new root-knot nematode, Meloidogyne pakistanica sp. n. (Nematoda: Meloidogynidae)

摘要

A root-knot nematode Meloidogyne pakistanica sp. n., was discovered on the roots of okra (Abelmoschus esculentus (L.) Moench.) from Punjab, Pakistan. The heavily infected okra field showed decline in plant growth and yield, infected feeder roots weredistorted and showed numerous root galls of moderate to large size. Morphometric traits and phylogenetic trees derived from maximum parsimony analysis based on 18S rDNA showed that this nematode species clearly differs differs from other previously described root- knot nematodes. The new root-knot nematode species can be distinguished from other Meloidogyne spp. by the roundish perineal pattern, with broken fine wavy cuticle striae, interrupted by prominent lateral lines; striae closely spaced; dorsal arch low, stylet cone slightly curved dorsally about half of the stylet length and distance from anterior end to excretory pore of female is rather long (50-72 u.m). Female excretory pore distance from the anterior end and/length of stylet (ratio (EP/ST)is 2.8-4.5. In second stage juveniles, the DGO is located 2-4 (im posterior to stylet base; and the tail is 42-58 im long with a conoid pointed terminus. Males have lateral fields composed of six incisures with areolated outer bands. Phylogenetic treesderived from maximum parsimony analysis based on 18S rDNA showed that Meloidogyne pakistanica sp. n., M. hispanica, M. enterolobii and M. thailandica formed a monophyletic group with bootstrap support of 100%.These observations provide further evidence for the distinctness of this species.