Description of Bursaphelenchus ulmophilus sp. n. (Nematoda: Parasitaphelenchinae) associated with Dutch elm disease of Ulmus glabra Huds. in the Russian North West

Abstract

A new species, Bursaphelenchus ulmophilus sp. n., from the hofmanni group is described morphologically and molecularly. This nematode species was found associated with Dutch elm disease of Ulmus glabra in parks of St Petersburg, Russia, and is vectored by adults and larvae of the bark beetles Scolytus multistriatus and S. scolytus. Bursaphelenchus ulmophilus sp. n. is characterised by the following features: body length 600-850 μm, stylet 12-14 μm long with base slightly and smoothly expanded, but lacking knobs, median bulb almost spherical in female and slightly ovoid in male, pharyngeal gland lobe dorsal, 4-5 body diam. long. This species has an oval spermatheca filled with spherical nucleic sperm 4-5 μm diam. Female post-uterine sac ca 0.5 of the vulva-anus distance and ca 3 vulval body diam. long, female tail reflexed, strongly hooked ventrally with a digitate or conically rounded tip. The male has seven caudal papillae arranged as 1 + 2 + 2 + 2, P1 is unpaired, anterior to cloacal opening, paired P2 at cloacal aperture, paired P3 and paired pore-like 'gland papilla' P4 at the lateral edges of the bursa which has the posterior border rounded to truncate. Phylogenetic analyses of the D2-D3 of 28S rRNA, partial 18S rRNA and ITS rRNA gene sequences revealed that B. ulmophilus sp. n. formed a clade with species of the hofmanni group and shared close relationships with B. hofmanni and B. pinasteri.

Biological Flora of the British Isles: Ulmus glabra

“…n. (Nematoda, Parasitaphelenchinae) has been found in U. glabra suffering from DED, carried by the Scolytus spp. elm beetles (Ryss, Polyanina, Popovichev, & Subbotin, ). Many Bursaphelenchus species are known to be associated with the wood of various trees, particularly conifers, and in some are notable pests.…”

Report of Bursaphelenchus crenati Rühm, 1956 (Nematoda: Parasitaphelenchinae) from Belarus and Russia with a diagnostic key and phylogeny of the Sexdentati group

“…Similar host–parasite relations were found for Bursaphelenchus ulmophilus in St. Petersburg. In all living elm trees ( Ulmus glabra and U. laevis ) dying from fungal infection caused by Ophiostoma novo‐ulmi vectored by the bark beetle Scolytus multistriatus , the nematodes B. ulmophilus were found in the phloem and sapwood, and their dauers were found under elytra and around head of S. multistriatus (Ryss et al, and unpublished data). In the case of B. ulmophilus, it may be supposed that the nematode and its beetle vector additionally stressed the infected tree destroying its cambium, phloem and active xylem (sapwood).…”

“…from the GenBank (Lange, Burgermeister, Metge, & Braasch, ; Ye, Giblin‐Davis, Braasch, Morris, & Thomas, ; Dayi et al, ; Marek, Zouhar, Douda, Gaar, & Rysanek, , Gu et al, , Tomalak, Malewski, Gu, & Zhan, and others) were also used for phylogenetic reconstruction. Outgroup taxa for each data set were chosen according to previously published data (Ryss, Polyanina, Popovichev, & Subbotin, ). The newly obtained and published sequences for each gene were aligned using Clustal X.…”

Characterization of Juvenile Stages of Bursaphelenchus crenati Rühm, 1956 (Nematoda: Aphelenchoidoidea)

“…Female juvenile. (Ryss et al, 2015). Difference between the Bursaphelenchus clades in the dauer juvenile stages (J3D or J4D) is the important character for the genus Bursaphelenchus phylogeny and intrageneric taxonomic diagnostics (Ryss and Subbotin, 2017).…”