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

Abstract

An undescribed Bursaphelenchus 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 Pinus armandii var. amamiana on two islands (Yakushima and Tanegashima) in Kagoshima, Japan. The new nematode is described and illustrated herein as B. osumiana n. sp. Typologically, B. osumiana n. sp. is similar to B. parvispicularis and B. paraparvispicularis, i.e., 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 B. osumiana n. sp., and were close to those of B. parvispicularis and B. paraparvispicularis. 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, e.g., carrier insect species and pathogenicity with regard to pine tree species, have not been clarified and should be examined in future studies.

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

“…Similar conclusions on the evolution of relationships between Bursaphelenchus spp. and their woody Pinaceae and deciduous hosts were drawn by Kanzaki (Kanzaki, 2006;Kanzaki et al, 2014). The absence of strong co-evolution pattern of species in the hofmanni group with their plant hosts may be explained by their type of feeding: the nematodes feed and multiply in the wood of dying and dead trees and thus they do not depend on deep physiological relations with their plant hosts.…”

“…14.5 15.3 ± 1.0 (14.0-17.0) 12 ± 2.0 (11.0-15.0) 8.6 ± 1.2 (7.0-10.0) 9.7 ± 1.3 (8.0-11.0) Annuli (width of 12 12 ± 2.0 (10-15) 13 ± 2.0 (11-15) --10 at mid-body) Spicule length ( 19.0°18.6 ± 5.3 (12.0-28.0)°---along capitulum (condylus-rostrum) and extending spicule end (dorsal intersection) straight condylus; from B. ratzeburgii Rühm, 1956 in ratio of PUS to vulva-anus distance = 0.49 (0.46-0.51) vs 0.29 (0.28-0.3) (calculated from figures in original species description), female tail tip reflexed and digitate vs not reflexed and mucronate; from B. gerberi Giblin-Davis, Kanzaki, Ye, Center & Thomas, 2006 in spicule shape with the line along the capitulum (condylus-rostrum) and line extending the spicule end crossing dorsally vs ventrally (this character was used in: Giblin-Davis et al, 1993, 2006Ryss et al, 2005), condylus and rostrum equally prominent vs condylus very long and truncate and rostrum short; from B. anamurius Akbulut, Braasch, Baysal, Brandstetter & Burgermeister, 2007 in spicule length = 16 (13-18) vs 10 (9-11) μm, condylus well developed vs completely reduced, vulval flap small but distinct vs absent, tail tip reflexed vs only slightly curved; from B. corneolus Massey, 1966 in spicule shape with condylus and rostrum of equal length vs condylus very long and truncate and rostrum very short; the ratio of PUS length to VBD Kanzaki, Akiba, Kanetani, Tetsuka & Ikegame, 2014 in spicule shape with ratio of spicule length to its width posterior to rostrum = 3.9 (3.3-4.5) vs 2.0 (1.9-2.1) (calculated from figures in original species description), condylus prominent vs condylus small, not developed, cucullus well developed vs cucullus small and indistinct: PUS = 3.1 (2.6-3.4) vs 6.6 (5.4-7.2) VBD (calculated from measurements in original species description), female tail relatively shorter with c = 3.4 (3.1-3.5) vs 4.3 (4.0-5.0); from B. paracorneolus Braasch, 2000 in spicule shape with line along capitulum (condylus-rostrum) and line extending the spicule end crossing dorsally vs ventrally; spicular lamina mid-point of B. ulmophilus sp. n. moderate in width and not mitten-shaped vs excessively widened to mitten-shaped, condylus slightly flexed dorsally vs condylus dorsal line appearing as a straight continuation of dorsal lamina, ratio of PUS to VBD = 3.1 (2.6-3.4) vs 2.0 (1.7-2.4) (calculated from measurements in original species description); from B. paraparvispicularis Gu, Wang, Duan, Braasch, Burgermeister & Zheng, 2010 in the presence of a small cucullus at the spicule tip vs lack of a distinct cucullus, presence vs absence of a vulval flap, female tail relatively long with c = 3.4 (3.1-3.5) vs 2.8 (2.4-3.2), and tail tip reflexed vs only slightly ventrally curved; from B. parapinasteri Wang & Jang, 2007 in spicule shape which has the condylus long and slightly reflexed vs very short and perpendicular to the dorsal lamina of spicule (as in B. xylophilus group males), cucullus present vs absent, bursa bluntly rounded or truncated vs narrowly conical, female tail tip reflexed ventrally vs slightly curved ventrally and almost straigh...…”

Description of Bursaphelenchus rockyi n. sp. (Nematoda: Aphelenchoididae) in peat moss from Russia

“…) Bursaphelenchus osumiana is a junior synonym of B. wuae(Huang & Ye, 2006;Kanzaki et al, 2014b;Gu et al, 2017).…”