Search Results

You are looking at 1 - 10 of 55 items for

  • Author or Editor: Jianfeng Gu x
  • Search level: All x
Clear All

Bursaphelenchus paraburgeri sp. n., isolated in Ningbo, China, from packaging wood of deciduous trees imported from Malaysia is described. It is characterised by a slim body (a=32-37), lateral field with four lines, excretory pore located anterior to the metacorpus, vulva at 75% of total body length, presence of a thick vulval flap in lateral view, post-uterine branch about two-thirds of the vulva-anus distance long, female tail long and conical (c=15), tapering to a finely rounded or bluntly pointed terminus, spicules have only weakly developed rostrum and condylus, and cross-striped in their central part, three pairs of ventro-sublateral papillae (one pair precloacal, two pairs postcloacal just anterior to the bursal flap and adjacent to each other) and a single precloacal midventral papilla. The new species belongs to the africanus group of the genus Bursaphelenchus and is most similar to B. burgermeisteri and B. obeche, from which it can be distinguished, as well as from other Bursaphelenchus species, by morphology, ITS-RFLP patterns and sequencing results.

In: Nematology

Ruehmaphelenchus digitulus sp. n., isolated from coniferous packaging wood from Taiwan, is described and figured. The new species is characterised by a relatively stout body with a = 28.0 (23.7-31.3) and 27.0 (22.9-32.7) for male and female, respectively, three lines in the lateral field, spicules relatively small (chord = 17.0-19.2 μm; arc = 13.8-16.6 μm) with weakly developed condylus and rostrum, bursa absent, vulva positioned at ca 80% of body length, vulva flap absent, vulval lips slightly protruding, post-uterine branch extending slightly over half of vulva to anus distance, and tail conoid, ca 2-3 anal body diam. long, with terminal process 7-10 μm long. The new species is the fourth known for the genus. It can be distinguished from R. martinii, R. asiaticus and R. thailandae mainly by the different shape and size of the spicules and the different shape and length of the female tail terminus. The separate species status is also supported by ITS-RFLP pattern and molecular phylogenetic analysis based on partial SSU ITS1/2 and partial LSU sequences.

In: Nematology

Summary

Cryptaphelenchus recticaudatus n. sp. is described and illustrated in Pinus elliottii from the USA. The new species is characterised by the female body 310-431 μm long with distinctly annulated cuticle, lateral fields with four lines, lip region separated from the body by a shallow depression, delicate stylet with small knobs, post-vulval uterine sac short, and rectum and anus invisible. Males are 228-314 μm long, spicules 9.8-12.4 μm long with a well-developed and broad condylus, and seven caudal papillae arranged as a single (P1) and pair (P2) of precloacal papillae plus two pairs of postcloacal papillae. Based upon the general female morphology, the new species most closely resembles C. baujardi and C. iranicus. The morphological differences with the aforementioned species and other species of the genus are discussed. The phylogenetic analyses based on small (SSU) and large subunit (LSU) D2-D3 expansion segments of ribosomal DNA of different individuals of the new species revealed that the new species fell into the Cryptaphelenchus clade in both SSU and LSU trees. The monophyly of the genus was retained after adding newly generated sequences of the new species.

In: Nematology

A small-scale, but highly-stylized dynamic stochastic general equilibrium model is estimated by the maximum likelihood method using Chinese quarterly data. Model specifications and parameter equalities between various competing model variants are addressed by formal statistical hypothesis tests, while implications for business cycle fluctuations are evaluated via a variance decomposition experiment, second-moments matching, and some out-of-sample forecast exercises. It is highlighted that the monetary authority takes an aggressive stance to the current inflation pressure (there is a significant lagged response), while leaving less attention to changes in aggregate output. Variance decomposition reveals that large percentages of variations in real and nominal variables are explained by the highly volatile preference and potential output shock, respectively. When nominal and real frictions as well as additional shocks are included, overall our estimated model can successfully reproduce the stylized facts from actual data of Chinese business cycles and frequently can even outperform those forecasts from an unconstrained VAR.

In: Frontiers of Economics in China

Ektaphelenchus taiwanensis sp. n. is described and figured. The new species was isolated from pine packaging wood from Taiwan and inspected in Ningbo harbour, China, in 2009. Ektaphelenchus taiwanensis sp. n. is characterised by the lip region lacking a clear constriction separating it from the body contour, stylet relatively short (12-17 μm) and without basal knobs, and presence of three lines in the lateral field. The female post-uterine sac is less than a body diam. long, the rectum and anus are absent and the tail is conoid with a sharply pointed terminus. The male tail is conoid and has a hair-like mucron (0.5-2.5 μm), the spicules are mitten-shaped, 12.5-14.4 μm long (chord) and are smoothly curved with a prominent rounded condylus, prominent pointed rostrum, and broadly rounded distal end. There are three pairs of subventral caudal papillae. Ektaphelenchus taiwanensis sp. n. is similar to E. betulae, E. josephi, E. joyceae, E. prolobos, E. propora and E. tuerkorum from which it can be separated by a combination of various morphometric and morphological characters. The D2D3 LSU and partial SSU region sequences were analysed and aligned using ClustalW implemented in MEGA version 4.0. Phylogenetic trees were generated with the Neighbour Joining (NJ) method using the Tajima-Nei distance option. The feeding habit of the new species is briefly discussed.

In: Nematology

Bursaphelenchus koreanus sp. n., isolated in Ningbo, P.R. China, from packaging wood made from Pinus sp. imported from South Korea, is described. It is characterised by a slim body (a = 28-35), lateral field with four lines, excretory pore located at level of, or slightly posterior to, median bulb, vulva at 75% of total body length, presence of a distinct vulval flap in lateral view, post-uterine branch extending for ca two-thirds of vulva-anus distance, female tail conical and ventrally bent with slightly pointed, irregular or roughened terminus (c′ = 4.1), spicules large and arcuate (27-34 μm) with pointed rostrum, cucullus visible but sometimes reduced to a small blunt extension. The new species belongs to the xylophilus group and is most similar to B. luxuriosae and B. paraluxuriosae. It is distinguished from other Bursaphelenchus species by morphology, ITS-RFLP patterns and sequencing results.

In: Nematology

Abstract

Ruehmaphelenchus thailandae n. sp., isolated from deciduous dunnage from Thailand, is described and figured. The new species is characterised by the relatively stout body (a = 28.6 and 27.6 for males and females, respectively), three lines in the lateral field, spicules relatively small (12.0-13.3 μm) with weakly developed condylus and rostrum, bursa absent, vulva located at 79.5% of body length, vulval lips slightly swollen, length of post-uterine branch more than half of vulva to anus distance, female tail conoid, ca two anal body diam. long and with a broad terminal process up to 12 μm long. The new species is the third known for the genus. It can be distinguished from R. martinii and R. asiaticus mainly by the different shape and size of its spicules and different shape of the female tail terminus. The separate species status is also supported by ITS-RFLP pattern. Additional measurements of paratype R. asiaticus are appended.

In: Nematology

Summary

Ruehmaphelenchus americanum n. sp., isolated from southern yellow pine (Pinus taedae L.) from the USA is described and figured. It is characterised by a relatively stout body (a = 30 for females and males), three lines in the lateral field, both oocytes and spermatocytes arranged in two rows, male spicules relatively small (14-18 μm) with weakly developed condylus and rostrum, short tail with a bluntly pointed tip, seven papilliform genital papillae present, female vulva positioned at ca 82% of body length, vulval lips slightly protruding, post-uterine branch extending two-thirds of vulva to anus distance, tail cylindrical, ca two anal body diam. long, terminus forming a spike-like projection or mucron, 7.6-12.2 μm long, with pointed tip. The new species can be separated from 11 known species (except R. thailandae) by male genital papillae arrangement (the second and third pair adjacent vs separated). Detailed phylogenetic analysis based on 18S and 28S D2-D3 region ribosomal RNA (rRNA) sequences has confirmed the status of this nematode as a new species.

In: Nematology

Bursaphelenchus parapinasteri is redescribed morphologically and with new molecular characterisation. It was isolated from a dead Pinus thunbergii on Changgang Mountain, Zhoushan Islands, Zhejiang Province, China. Detailed morphology of the spicule, female gonad, hemizonid position, arrangement of male caudal papillae, and female tail terminus shape are documented. The ITS-RFLP patterns and the ITS1/2, partial 28S D2-D3 and partial 18S gene sequences were characterised. The phylogenetic analyses revealed that B. parapinasteri belongs to the hofmanni-group sensu Braasch and is close to B. anamurius, B. hofmanni, B. mazandaranense, B. paracorneolus, B. pinasteri and B. ulmophilus. A diagnostic key to species of the hofmanni-group is presented.

In: Nematology