Bursaphelenchus niphades n. sp. (Tylenchina: Aphelenchoididae) amensally associated with Niphades variegatus (Roelofs) (Coleoptera: Curculionidae)

Abstract

ABursaphelenchusspecies was isolated from a Japanese native wood-boring weevil,Niphades variegatus, and dead Pinaceae trees. The nematode is associated with the weevils as dauer (dispersal third stage) juveniles and the dauers enter the weevil tracheal system forming an abnormal expansion on the weevil trachea (atrium). Thus, the nematode is hypothesised to be an amensal/phoretic associate of the weevil because the abnormal expansion appeared to inhibit weevil respiration. The propagative stages of the nematode are associated with dead trees (wood and bark materials) and are thought to feed there on naturally propagated fungi. Morphologically, the new species is considered an undescribed species close toB. antoniae,B. chengiandB. hylobianum. Within these four species, the new species, which is described herein asB. niphadesn. sp., is closest toB. chengi,i.e., the typological character of these two species are almost identical to each other and is distinguished by some minor characters (structure of the male P4 genital papillae and spicule length). The molecular phylogenetic analysis supported the morphological observations.Bursaphelenchus niphadesn. sp. formed a well supported subclade with the four species and is intermediate betweenB. hylobianumandB. chengi; however, it is distinguished by the molecular sequences of some ribosomal RNA genes. Because three of these four species are associated with weevil species, the subclade is considered a ‘weevil-associated’ species group.