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Natsumi Kanzaki

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Natsumi Kanzaki

Abstract

Aphelenchoides xylocopae n. sp. is described and figured. The new species was isolated from the Japanese large carpenter bee, Xylocopa appendiculata circumvolans, and reared on a lawn of Botrytis cinerea. Specimens were collected from a 2-week-old culture on the fungus. The new species has a body length of 514-638 μm (males) and 532-674 μm (females). The cuticle is weakly annulated and there are three lines in the lateral field. The stylet is 10-11 μm long and has small basal swellings. Spicules are large (23-28 μm) and strongly arcuate. The male tail bears six (2 + 2 + 2) caudal papillae and is mucronate. The female tail is tapered to a pointed, amucronate or mucronate, terminus. The new species belongs to the Group 2 category of Aphelenchoides species. Cultured nematodes were used for sequencing the partial (ca 1 kbp) cytochrome oxidase subunit I of mitochondrial DNA and partial (ca 900 bp) small subunit ribosomal DNA for comparison with the sequences deposited at GenBank. The DNA sequences of A. xylocopae n. sp. were close to those of other Aphelenchoides and Bursaphelenchus species in the database, but the precise phylogenetic status of the new species could not be determined because of the limited sequences available for Aphelenchoides species.

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Natsumi Kanzaki, Natsumi Kanzaki and Mitsuteru Akiba

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Natsumi Kanzaki and Kazuyoshi Futai

Abstract

Bursaphelenchus parvispicularis n. sp. is described and figured. The new species was isolated from the bark of a dead oak tree, Quercus mongolica var. grosseserrata, and reared on Botrytis cinerea. Specimens were collected from a 2-week-old culture on Botrytis cinerea. The new species has a body length of 894 (711-1012) μm in the female and 764 (600-870) μm in the male, a ratio of 33.4 (29.7-37.1) in the female and 35.6 (31.4-45.3) in the male, and c and c′ ratios of 16.7 (14.8-19.0) and 4.4 (3.9-5.1), respectively, in the female and 24.3 (20.0-28.4) and 2.5 (2.2-2.8), respectively, in the male. The stylet is 14-16 μm long in the female and 13-15 μm in the male; there are three lines in the lateral field; the spicules are small (13 (13-15) μm long) and broad; there are seven (2 + 1 + 2 + 2) male caudal papillae; the 'bursa' varies from roundish trapezoid to rectangular with a concave terminus, and the female tail is tapered with clearly annulated dorsal surface near the tail tip and a rounded terminus. Based upon morphology the new species belongs to the B. hofmanni-group sensu Braasch. However, the new species is distinguished from the other B. hofmanni-group species by the size and form of the spicule, female tail shape, and morphometric values. Based on the molecular phylogenetic analysis of the DNA base sequences of ribosomal DNA and mtCOI gene, the new species was close to two B. hofmanni-group species (B. paracorneolus and B. hofmanni) and to B. hylobianum. This result is in accordance with their morphological similarity.

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Natsumi Kanzaki and Tatsuya Ide

Diplogasteroides luxuriosae n. sp. is described from a species of longhorn beetle, Acalolepta luxuriosa (Cerambycidae), associated with a broad-leaved tree, Aralia elata (Araliaceae), from the Ibaraki and Kyoto Prefectures of Japan. Besides its generic (or intrageneric species group-specific) characteristics, the new species is characterised and distinguished from its close relatives by its apomorphic characteristics, i.e., broad spicule with a trapezoidal shape, gubernaculum with pointed anterior, and posterior ends with two gland-like cells dorsally overlapping the vas deferens of males and large and wide receptaculum seminis of females. The new species is molecularly similar to two recently described Diplogasteroides spp., D. andrassyi and D. asiaticus. However, D. luxuriosae n. sp. is molecularly distinguished from these two species by the 6-7 bp difference in near-full-length small subunit (18S) and 10-14 bp differences in D2-D3 expansion segments of large subunit (28S) ribosomal RNA genes.

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Noritoshi Maehara and Natsumi Kanzaki

We examined the transfer of Bursaphelenchus okinawaensis associated with Monochamus maruokai into M. alternatus and Psacothea hilaris using a simple nematode loading method in order: i) to clarify the effects of cerambycid beetles on the formation of dauer juveniles of B. okinawaensis; and ii) to clarify whether dauer juveniles transfer to cerambycid beetles other than M. maruokai. Dauer juveniles appeared at a high percentage without M. alternatus or P. hilaris and these beetles did not have any positive effects on their formation. Dauer juveniles transferred to the adults of M. alternatus and P. hilaris. We concluded that dauer juveniles of B. okinawaensis form readily without its vector beetles and may be able to transfer to many kinds of cerambycid beetles, although the numbers carried by a beetle are small.

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Natsumi Kanzaki and Ryusei Tanaka

A Sheraphelenchus species was isolated from a sample of sap exuding from a scar on the bark of Quercus serrata. Besides its generic characteristics, i.e., posteriorly located vulva in the female, male spicule with conspicuous dorsal limb and male tail with spike-like projection, the new species is characterised by a short stylet with a small basal swelling. The near-full-length of 18S and D2/D3 expansion segments of ribosomal RNA genes (near-full SSU and D2/D3LSU) were determined as its molecular barcode sequences and the phylogenetic status of the species (= genus Sheraphelenchus) was estimated using the near-full SSU. The molecular phylogenetic analysis revealed that the new species is included in the genus Bursaphelenchus, and is close to B. anatolius and B. kevini. Although Sheraphelenchus is phylogenetically inferred to occur within Bursaphelenchus, the new species is described herein as S. sucus n. sp., thereby retaining the genus Sheraphelenchus until additional data about morphological similarities between these two taxa are obtained.

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Natsumi Kanzaki and Kazuyoshi Futai

Abstract

The life history of the nematode Bursaphelenchus conicaudatus and its phoretic relationship to the yellow-spotted longicorn beetle, Psacothea hilaris, were studied, and are discussed by comparison with those of the pinewood nematode B. xylophilus, the pathogen of the pine wilt disease, and its vectors Monochamus species. The life history of B. conicaudatus was found to be very similar to that of B. xylophilus in dispersal pattern, vector selection and feeding preference, although the average number of B. conicaudatus carried by the yellow-spotted longicorn beetle, the proportion of beetles infested with the nematodes, and the nematode release pattern differed from those of B. xylophilus. These findings indicate a close relationship between the two species of Bursaphelenchus and the cerambycid beetles, as well as the adaptability of these two nematode species to the life cycles of their vectors.

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Natsumi Kanzaki and Kazuyoshi Futai

Abstract

The phylogenetic relationships of Bursaphelenchus conicaudatus with B. abruptus, B. fraudulentus, B. mucronatus and B. xylophilus species were analysed based on the DNA base sequences of 18S, 5.8S, ITS1 and ITS2 of rDNA and the partial code of mitochondrial cytochrome oxidase subunit I (COI) gene. The monophyly of B. abruptus and the other species in the xylophilus group was not supported, and B. abruptus could be excluded from the xylophilus group. The other species, i.e ., B. conicaudatus, B. fraudulentus, B. mucronatus and B. xylophilus were assumed to be monophyletic. The ancestor of these four species is assumed to have originated in the eastern part of the Eurasian continent as a free-living nematode inhabiting broad-leaved trees. First, B. conicaudatus branched from the ancestor in eastern Asia. Then B. fraudulentus and B. mucronatus separated from the ancestor. B. mucronatus changed its host from broad-leaved trees to conifers and spread throughout the coniferous forest over the Eurasian continent and North America. B. xylophilus might originate from a population of B. mucronatus remaining in North America after B. mucronatus had diversified.