Description of Bursaphelenchus ponderosae n. sp. (Nematoda: Parasitaphelenchidae), a bursaless species isolated from the mountain pine beetle Dendroctonus ponderosae (Coleoptera: Curculionidae)

Abstract

A new species of nematode associated with the mountain pine beetle, Dendroctonus ponderosae , in British Columbia, Canada, is described. Adult beetles consistently carried juvenile dauer stages of the nematode on their exteriors, particularly under the elytra and on the hindwing. The nematodes reproduced successfully in culture on Grosmannia clavigera , a bluestain fungus associated with the beetle. In addition to the mycetophagous form, a predatory form ( Ektaphelenchus -like) was observed in old cultures. Phylogenetic analysis of SSU and LSU ribosomal rRNA place the new species in the genus Bursaphelenchus , closely related to B. sinensis . The new species is characterised by the lack of a bursa, gubernaculum and vulva flap and is of moderate body length with females and males averaging 782 and 605  μ m respectively, a stylet length of 14.1-16.9  μ m with knobs in females, a narrow lateral field 1/8th the maximum body width with two lines. The spicules are <22  μ m long (19.5-21.5) with fused tips, dorsal lamina prominate, a more or less round condylus, a somewhat differentiated and round rostrum and without a cucullus. The male tail has 7 caudal papillae in total: P1, P2, P3, P5; P1 (unpaired) papilliform, P1 is located 2-4  μ m anterior to cloacal opening, P2 paired papilliform at same level of or slightly anterior to P1 but at lateral borders of cloacal opening, both P3 and P5 posterior to cloacal opening, P3 paired close to lateral borders and P5 paired located ventral. This new species is most similar morphologically to B. sinensis .