Bursaphelenchus osumiana n. sp. (Tylenchomorpha: Aphelenchoididae) isolated from dead Pinus armandii var. amamiana in Osumi Islands in Japan

<jats:p>An undescribed <jats:italic>Bursaphelenchus</jats:italic> species was isolated and cultured from materials collected during a field survey of a declining endemic pine species. Two nematode isolates were obtained from dead <jats:italic>Pinus armandii</jats:italic> var. <jats:italic>amamiana</jats:italic> on two islands (Yakushima and Tanegashima) in Kagoshima, Japan. The new nematode is described and illustrated herein as <jats:italic>B. osumiana</jats:italic> n. sp. Typologically, <jats:italic>B. osumiana</jats:italic> n. sp. is similar to <jats:italic>B. parvispicularis</jats:italic> and <jats:italic>B. paraparvispicularis</jats:italic>, <jats:italic>i.e.</jats:italic>, males of these species have a short, stout spicule. The new species is distinguished from the other two by the shape of the male bursal flap (very small and triangular) and female tail morphology (weakly ventrally arcuate with narrow rounded or weakly pointed terminus), which are unique to this species. Near full-length molecular sequences of the small subunit (18S), internal transcribed spacer region, and D2D3 expansion segments of the large subunit of ribosomal RNA and a partial sequence of the mitochondrial cytochrome oxidase subunit I (mtCOI) were obtained to molecularly profile the new species. The sequence profiles were identical for the two isolates of <jats:italic>B. osumiana</jats:italic> n. sp., and were close to those of <jats:italic>B. parvispicularis</jats:italic> and <jats:italic>B. paraparvispicularis</jats:italic>. The new species was clearly distinguished molecularly from both of its close relatives and its molecular phylogenetic status and typological characters were in accordance. Other biological characters, <jats:italic>e.g.</jats:italic>, carrier insect species and pathogenicity with regard to pine tree species, have not been clarified and should be examined in future studies.</jats:p>