Morphological and Molecular Characterization of Gracilacus wuae n. sp. (Nematoda: Criconematoidea) Associated with Cow Parsnip (Heracleum maximum) in Ontario, Canada

摘要

Gracilacus wuae n.sp.from soil associated with cow parsnip in Ontario, Canada is described and illustrated.Morphologically,femaleshavealongstyletrangingfrom80to93mmlong,thelipregionnotoffsetfromthebodycontour,withoutlaterallips butwithlargeand?atsubmedianlobes,themouthopeningslit-likeelongatedlaterallyandsurroundedbylateral?aps,theexcretory pore is anterior to the knobs of the stylet; males without stylet and the pharynx degenerated.The fourth-stage juveniles lack a stylet, the pharynx degenerated, and can be differentiated into preadult females and males based on the position of the genital primordia.The third-stage juveniles are similar to females but smaller.Phylogenetic studies using the rDNA small subunit 18S, large subunit 28S D2/D3, and internal transcribed spacer (ITS) sequences collectively provide evidence of a grouping with other Gracilacus and some species of Paratylenchus with stylet length of females longer than 41 mm deposited in GenBank.