A key and diagnostic compendium to the species of the genus Merlinius Siddiqi, 1970 (Nematoda: Tylenchida) with description of Merlinius khuzdarensis n. sp. associated with date palm

Abstract

Abstract An identification key to 32 valid species of stunt nematodes (Merlinius spp.) is given. A compendium of the most important diagnostic characters for use in identification of species is included as a practical alternative and supplement to the key. The diagnosis of Merlinius is emended and a list of all valid species of the genus is given. The characters most useful for separating species include body and stylet lengths, shape of head, tail and tail terminus, number of head and tail annules, position of vulva (V), and c′ ratio in females. Also useful are length and shape of spicules and gubernacula in males. A new stunt nematode, Merlinius khuzdarensis n. sp., from the rhizosphere of date palm (Phoenix dactylifera L.) from Khuzdar, Balochistan Province, Pakistan, is described and illustrated. This new species resembles M. bavaricus, M. communicus, M. bilqeesae and M. montanus, but differs from these species by the following: body and stylet length, shape of head, tail and tail terminus, number of head and tail annules, and position of phasmids. Because this species is limited in distribution, its economic importance in date palm and other cultivated crops within the region is not known.