Bursaphelenchus crenati Ruhm, 1956 (Tylenchina: Aphelenchoididae), a nematode associated with the Greater ash bark beetle, Hylesinus crenatus Fabricius, in dying ash, Fraxinus excelsior L., in Europe

New morphological, molecular and bionomic data are added to update the description of Bursaphelenchus crenati. The nematode was isolated from larval galleries and adults of the Greater ash bark beetle, Hylesinus crenatus Fabricius, present in bark of older trees of European ash, Fraxinus excelsior L., in Poland. Detailed female and male morphology are documented in this paper and compared with the original description. From ITS1/2, partial 28S D2-D3 and partial 18S sequences, ITS-RFLP patterns and morphological analysis, B. crenati is suggested to be temporarily placed into the sexdentati group, close to B. andrassyi, B. vallesianus, B. sexdentati, B. pinophilus, B. poligraphi, B. fuchsi, B. incurvus, B. piniperdae, and B. pityogeni. However, B. crenati can be distinguished from these species by the strongly ventrally curved body and the presence of three incisures in the lateral fields.