Phylogenetic relationships of three families of the suborder Mononchina Kirjanova & Krall, 1969 inferred from 18S rDNA.

Mononchida is an order of predatory nematodes and includes the suborders Bathyodontina and Mononchina. In this survey, sequences of the 18S rDNA were amplified and used to reconstruct the phylogeny of the Mononchina. Phylogenetic analyses using Neighbour Joining (NJ) and Maximum Likelihood (ML) were employed with five outgroup taxa and 65 mononch sequences including 14 new sequences from Iran. Both analyses indicated that the Anatonchus is monophyletic. Actus was placed as the sister group of Mylonchulus with weak and strong support, respectively, from the ML and NJ analyses. In both phylogenetic analyses, trees obtained from SSU rDNA alignments were subdivided into five highly- or moderately-supported clades, designated Clade I: Mylonchulus spp., Clade II: Actus salvadoricus, Clade III: Anatonchus spp., a group comprising the genera Clarkus, Coomansus, Miconchus and Prionchulus, Clade IV: Mononchus spp., and Clade V: Granonchulus sp. The 18S rDNA analysis demonstrated that this region of the nuclear genome can be used to resolve the relationships of members of this suborder. [ABSTRACT FROM AUTHOR]