Description of Bursaphelenchus taphrorychi sp. n. (Nematoda: Parasitaphelenchidae), the second Bursaphelenchus species from larval galleries of the beech bark beetle, Taphrorychus bicolor (Herbst.) (Coleoptera: Curculionidae: Scolytinae), in European beech, Fagus sylvatica L.

Abstract

Bursaphelenchus taphrorychi sp. n. is described from the bark of European beech, Fagus sylvatica. All propagative stages of the nematode are numerous in larval galleries of the beech bark beetle, Taphrorychus bicolor, while dauer juveniles are transmitted to new breeding trees under the elytra of adult beetles. The new species is characterised by the body length of 782 (717-858) μm in female and 638 (475-789) μm in male, moderately slender body (a = 35.0 (31.7-36.5) and 35.5 (31.4-37.1) in female and male, respectively), spicules 12.0-16.0 μm long, lateral fields with four incisures (i.e., three bands), and the arrangement of the seven male caudal papillae (i.e., a single precloacal ventromedian papilla (P1), one pair of adcloacal ventrosublateral papillae (P2), one postcloacal pair (P3) located at ca 60% of the tail length, posterior to the cloacal aperture, and one pair (P4) of subventral papillae of a similar size as the previous pair, but with somewhat sunken tips, located near base of bursa). In the number and arrangement of caudal papillae, stout and curved spicules with prominent rostrum and condylus, small vulval flap, body narrowed posterior to vulva, four incisures in the lateral fields, and long post-uterine sac, B. taphrorychi sp. n. shares most of the key morphological characters with members of the sexdentati-group. However, the newly described species is unique amongst Bursaphelenchus species of this group by the combination of shape of female tail, shape of spicules, and some other morphometric characters. The close relation of B. taphrorychi sp. n. with members of the sexdentati-group has been confirmed by DNA sequencing and phylogenetic analysis of the 28S rDNA region. The taxonomic separation of the new species is also confirmed by the unique molecular profile of the ITS region (ITS-RFLP). In laboratory rearing, B. taphrorychi sp. n. can develop and reproduce on Botrytis cinerea cultures.