Description of Xiphinema parachambersi sp. n. (Nematoda: Longidoridae) from Imported Ornamental Plants in Japan with a Key to Xiphinema Species in Group 1

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VOLUME 50 , ISSUE 3 (September 2018) > List of articles

Description of Xiphinema parachambersi sp. n. (Nematoda: Longidoridae) from Imported Ornamental Plants in Japan with a Key to Xiphinema Species in Group 1

Munawar Maria / Weimin Ye / Qing Yu / Jianfeng Gu *

Keywords : Molecular, morphology, morphometrics, nematode, new species

Citation Information : Journal of Nematology. Volume 50, Issue 3, Pages 369-386, DOI: https://doi.org/10.21307/jofnem-2018-027

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Published Online: 17-October-2018

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ABSTRACT

Xiphinema parachambersi n. sp. recovered in Ningbo, China, from the rhizosphere of ornamental plants (Gardenia jasminoides and Euonymus hamiltonianus) imported from Japan is described. The new species is characterized by a long female body 1,830 to 2,109 μm long, odontostyle 105 to 116 μm long, reproductive system mono-opisthodelphic, vulva located anteriorly at 25.2 to 27.7% of total body, long ovary 119 to 292 μm with simple uterus and Z-organ absent, female tail elongated conoid with a rounded terminus. Only two juvenile stages were available to study and no male was found. The polytomous identification codes for this new species are A1, B4, C2, D23, E1, F2, G2, H2, I2, J2, K?, L1 and it belongs to the morphospecies group 1. Phylogenetic analysis based on the 18S, ITS1 and 28S D2/D3 sequences of the new species showed close relationships with X. chambersi. Morphologically, the new species is similar to X. chambersi, X. hangzhouense, and X. winotoi but can be differentiated by morphological characters and DNA sequences. To help identify the species, a diagnostic key to the group 1 species is presented.

Graphical ABSTRACT

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Dagger nematodes (Xiphinema Cobb, 1913) contain more than 260 species (Palomares-Rius et al., 2017). They are polyphagous and ectoparasites on a variety of cultivated and wild plants. Their feeding behavior causes considerable mechanical damage to plants due to its excessive long stylet. The root symptoms include darkening of tissues, cortical hyperplasia, lateral root proliferation, tip galling, and necrosis (Hunt, 1993). In addition, nine Xiphinema species, three species from Xiphinema non-americanum group including X. index (Thorne and Allen, 1950), X. diversicaudatum (Micoletzky, 1927) (Thorne, 1939), and X. italiae (Meyl, 1953) and six putative species in the X. americanum group including X. americanum s. str., X. californicum (Lamberti and Bleve-Zacheo, 1979), X. bricolense (Ebsary et al., 1989, X. intermedium (Lamberti and Bleve-Zacheo, 1979), X. revesi (Dalmaso, 1969), and X. tarjanense (Lamberti and Bleve-Zacheo, 1979) are known to transmit nepoviruses, which cause additional indirect damages to plants (Hunt, 1993; Decraemer and Robbins, 2007). Because of their economic importance, species in Xiphinema have received considerable attention. Virus-transmitting Xiphinema species are listed as quarantine pests in many countries including China.

During a routine quarantine inspection, a Xiphinema population was detected from the soil samples from imported ornamental plants, Gardenia jasminoides J. Ellis and Euonymus hamiltonianus Wall. from Japan. The preliminary morphological investigation revealed that the species has a medium size body, opisthodelphic reproductive system, anteriorly located vulva and elongated tail, very similar to North American species X. chambersi (Thorne, 1939).

In order to make the final species identification, a detailed morphological and DNA sequencing analysis was conducted which resulted in a new species and was herein described as X. parachambersi n. sp. The objectives of the present study were to: (i) provide a morphological description of the new species and compare it with other similar species; (ii) characterize the species molecularly, using three DNA markers, 18S, ITS1, and 28S D2/D3 ribosomal (iii) examine the phylogenetic relationships of the new species with other species in Xiphinema.

Materials and methods

Nematode samplings, extraction, and morphological study

Xiphinema specimens were collected from the rhizosphere of Gardenia jasminoides (sample number: 2186-1) and Euonymus hamiltonianus (sample number: 2186-2) from the same container using modified Baermann funnel method for 24 to 48 hr. Measurements were made on specimens fixed in TAF and processed to glycerin following the method of Seinhorst’s (1959). The nematodes were measured using AxioVs40 (v4.6.3.0) of Zeiss company. All the abbreviations used are as defined in Decraemer and Hunt (2006). Light micrographs were made using a Zeiss Imager Z1 microscope equipped with a Zeiss AxioCam MRm CCD camera. Drawings were made with a drawing tube. Juvenile stages were determined by a plot with scattergraph method of the lengths of odontostyles and replacements.

Molecular analyses

For DNA extraction, a single nematode was transferred to worm lysis buffer (WLB: 20 mM Tris-HCl pH 8.0, 100 mM KCl, 3.0 mM Mg2Cl, 2.0 mM DTT, 0.9% Tween) and crushed with a sterilized pipette tip. The crushed nematode was pipetted into 8 µl ddH2O with 2 µl proteinase K (60 µg/ml) in an Eppendorf tube, which was then briefly spun and stored at −70°C for at least 10 min. Subsequently, the Eppendorf tube was incubated at 65°C for 1 to 2 h and the proteinase K was denatured at 95°C for 10 min. Finally, the DNA suspension was cooled to 4°C and used for conducting PCR (Li et al., 2008). Three sets of primers (synthesized by Invitrogen, Shanghai, China) were used in the PCR analyses to amplify the partial 18S, ITS1, and 28S rDNA D2/D3. Primers for amplification of 18S were forward primer K4f and reverse primer K1r (Penas et al., 2006). Primers for amplification of ITS1 were forward primer V1 (Ferris et al., 1993) and reverse primer 5.8S (Cherry et al., 1997). Primers for amplification of 28S D2/D3 were forward primer D2A and reverse primer D3B (De Ley et al., 1999). The 25-µl PCR was performed using Master Mix DNA polymerase (Invitrogen, Shanghai, China) according to the manufacturer’s protocol in a thermocycler. The thermal cycler program for 28S was as follows: denaturation at 95 °C for 5 min, followed by 35 cycles of denaturation at 94 °C for 30 s, annealing at 55 °C for 45 s, and extension at 72 °C for 2 min. A final extension was performed at 72 °C for 10 min. The thermal cycler program for 18S and ITS was as follows: denaturation at 95 °C for 5 min, followed by 35 cycles of denaturation at 95 °C for 60 s, annealing at 55 °C for 60 s, and extension at 72 °C for 2 min. A final extension was performed at 72 °C for 5 min as described by Ye et al. (2007) and Li et al. (2008). PCR products were separated and visualized on 1% agarose gels and stained with ethidium bromide. PCR products of sufficiently high quality were sequenced by Invitrogen (Shanghai, China).

Phylogenetic analysis

The sequences were deposited into the GenBank database. DNA sequences were aligned by MEGA7 (Kumar et al., 2016.) using default settings. The DNA sequences were compared with those of the other nematode species available at the GenBank sequence database using the BLAST homology search program. The model of base substitution was evaluated using MODELTEST (Posada and Criandall, 1998; Huelsenbeck and Ronquist, 2001). The Akaike-supported model, the base frequencies, the proportion of invariable sites and the gamma distribution shape parameters and substitution rates were used in phylogenetic analyses. Bayesian analysis was performed to confirm the tree topology for each gene separately using MrBayes 3.1.0 (Huelsenbeck and Ronquist, 2001) running the chain for 1 × 106 generations and setting the “burnin” at 2,500. We used the Markov Chain Monte Carlo (MCMC) method within a Bayesian framework to estimate the posterior probabilities of the phylogenetic trees (Larget and Simon, 1999) using 50% majority rule.

Results

SYSTEMATICS

Xiphinema parachambersi n. sp.

(Table 1; Figs. 1-4)

Table 1

Morphometrics data for Xiphinema parachambersi n. sp. All measurements are in µm and in the form of mean ± s.d. (range).

10.21307_jofnem-2018-027-t001.jpg

Description

Female

Body thin, almost straight in the anterior half, posterior portion bending ventrally, open “C” shaped upon fixation, narrows gradually and evenly in the tail region. Cuticle smooth and rather thick, lateral cords not visible. Lip region flattened, cephalic region rounded and, offset by weak depression. Amphids stirrup-shaped, fovea with wide slit-like aperture, slightly narrower than lip width. Five to six body pores present between anterior end and guiding ring on the dorsal and ventral side, respectively. Odontostyle (9–12) times lip region width. Odontophore with well-developed basal flanges (8.8–11.5 μm wide). Guiding ring double, guiding sheath 12 to 17 μm long depending on degree of protraction/retraction of stylet. Esophagus, extending to a terminal Esophageal bulb with three nuclei, dorsal gland nucleus located at the beginning of bulb i.e. (12–17%) of the esophageal bulb length, two subventral-lateral nuclei located around the middle of bulb (SV1 = (51–53%); SV2 = (52–54%). Esophageal basal bulb (77.4–85.1) μm long and (22.5–26.5) μm wide. Esophageal intestinal valve (cardia) not well developed, 7.6 to 8.8 μm long, wide lumen appeared as two separated parts hanging on the base bulb, free in the intestine lumen, in a few specimens conoid-oblonged shaped. Intestine simple, rectum 30.4 to 40.8 μm long. Female reproductive system mono-opisthodelphic, undifferentiated uterine sac, 8.4 to 12.3 μm long. Posterior genital branch 119 to 292 μm long, reflexed, vulva a transverse slit, vagina thick walled (16–19 μm long), slightly directed posteriorly, ovijector well developed, 17 to 21 μm wide, extending inwards less than half of the corresponding body diameter, uterus short and undifferentiated, Z organ absent. Tail elongated, ventrally curved, tapers gradually and evenly forming a rounded terminus bearing two body pores.

Fig. 1

Line drawings of Xiphinema parachamberi n. sp. female. A: Esophageal region; B: Esophageal bulb; C: Entire body; D: Genital branch; E: Tail region (Scale bars: A, E = 40; B, C=20, D=100 μm).

10.21307_jofnem-2018-027-f001.jpg
Fig. 2

Light photomicrographs of Xiphinema parachamberi n. sp. female. A: Anterior region, arrow showing position of vulva (v); B: Lip region; C-E: Esophageal bulb (arrows showing different position of gland nuclei); F: Esophago-intestinal junction arrows pointing the base of pharyngeal bulb and cardia. G: Vulval region; H, I: Gonad; J: Female tail (arrows showing position of (a) anus and caudal pores); K, L: Female tail (arrows showing position of (a) anus) (Scale bars: A, L = 10 μm).

10.21307_jofnem-2018-027-f002.jpg
Fig. 3

Light photomicrographs of cardia of Xiphinema parachamberi n. sp. Scale bars: A–C=20 μm).

10.21307_jofnem-2018-027-f003.jpg
Fig. 4

Light photomicrographs of Xiphinema parachamberi n. sp. juveniles and female. A–D: Anterior regions of J2/J3, J3/J4 and female; E–H: Tail regions of J2/J3, J3/J4 and female (arrows showing position of anus (a)) (Scale bars: A–L = 10 μm).

10.21307_jofnem-2018-027-f004.jpg
Fig. 5

Relationship of body length to length of functional and replacement odontostyle (Ost and rOst, respectively); length in two juvenile developmental stages and mature females of Xiphinema parachambersi n. sp.

10.21307_jofnem-2018-027-f005.jpg

Male

Not found.

Juveniles

Two juvenile stages, either J2/J3 orJ3/J4 were found and they were morphologically similar to adults except for their smaller size, shorter tails, and sexual characteristics. There is an immediate and quick progression of odontostyle length which makes it difficult to distinguish between juvenile stages. However, the characteristic feature of J1 as having replacement odontostyle being embedded in the base of odontophore was not observed in any of the juvenile specimens. Based on the information obtained through scatter graph (Fig. 5), it is not clear whether three or four juvenile stages are present in this species because only two juvenile stages were available to study.

Type host and locality

The type specimens were extracted from the rhizosphere of Gardenia jasminoides (2186-1) and Euonymus hamiltonianus (2186-2) trees from the same container imported from Japan on June 2016 and intercepted at Ningbo Port, P. R. China.

Type specimens

Holotype female and nine female paratypes (slide numbers 2186-1 to 2186-8) were deposited in the nematode collection of Ningbo Entry–Exit Inspection and Quarantine Bureau, China. Five paratype females (slide numbers T550a-e) were deposited in the Canadian National Collection of Nematodes, Ottawa, Canada.

Differential diagnosis

Xiphinema parachambersi n. sp. is a mono-opisthodelphic species characterized by the female having an elongated tail with round terminus, with a hyaline part over one-third of the tail length, the cardia with wide lumen, total stylet length = 169 to 181 μm, vulva located anteriorly at 25.2 to 27.7% of the total body length. Based on the polytomous key of Xiphinema species presented by Loof and Luc (1990) and Loof et al. (1996), the new species belongs to the morphospecies group 1 and has the following specific diagnostic alphanumeric codes: A1, B4, C2, D23, E1, F2, G2, H2, I2, J2, K?, L1.

Morphospecies group 1 represents species having single gonad (monodelphic), all the known species in this group are small and have an anteriorly located vulva, simple or undifferentiated posterior uterus, lacking Z organ (Cohn and Sher, 1972). With the most recent described X. hanzhouense (Cai et al., 2018), there are 12 nominal species in this group. The important characters to distinguish these species are the shape and lengths of tail and its hyaline region.

Xiphinema parachambersi n. sp. is morphologically most similar to X. chambersi, but can be differentiated by cardia (weakly developed with wide lumen vs well developed with narrow lumen), shorter tail (98.0–120.3) vs (110.2–177.3) μm, longer hyaline part (39.4–47.2) vs (22–43.4) μm, slightly shorter body, (1830–2109) vs (2100–2400) μm, more anteriorly located guide ring, (92.1–102) vs (105.4–115) μm from anterior end, shorter anterior undifferentiated sac, (8.4–12.3) vs (13.9–21) μm and higher H%, (34.4–43.4) vs (19.9–34.4).

The new species can be differentiated from X. hangzhouense by a pronounced shorter hyaline tail part, (39.4–47.2) vs (62.4–81) μm, more anteriorly located vulva, V= (25.2–27.7) vs (27.6–31.2), shorter odontostyle, (105.0–115.6) vs (117–128) μm, anterior undifferentiated sac (present vs absent) and tail terminus (rounded vs clavate); from X. manasiae Sen et al., 2010 by a longer tail (98.0–120.3) vs (61–86) μm, longer hyaline part (39.4–47.2) vs 20 μm (based on the drawings), slightly anterior vulva, V = (25.2–27.7) vs (30.2–33) %, longer odontostyle, (105.0–115.6) vs (98–105.3) μm, shorter anterior undifferentiated sac (8.4–12.3) vs (27–59) μm; from X. naturale (Lamberti et al., 2002) by the elongated tail with c′ (4.2–6.0) vs a tail somewhat conoid, c′ (2.5–3.5), shorter body, 2008 (1,830–2,109) vs (2,500–3,000) μm, slightly posterior vulva, V = (25.2–27.7) vs (22–25) %, shorter odontostyle, (105.0–115.6) vs (130–140) μm, longer tail, (98.0–120.3) vs (70.6–88.2) μm, longer hyaline tail region, (39.4–47.2) vs (19.5–26.5); from X. orthotenum (Cohn and Sher, 1972) by shorter tail, (98.0–120.3) vs (136–197) μm, tail elongated vs somewhat filiform, c′ = (4.2–6.0) vs (7.0–10.5), and shorter odontostyle, (105.0–115.6) vs (110–127) μm; from X. winotoi (Rahman-Razak and Loof, 1998) by tail curved ventrally vs straight or bent slightly dorsally, shorter hyaline tail region, (39.4–47.2) vs (62–74) μm, shorter odontostyle, (105.0–115.6) vs (125–148) μm; from X. monohysterum (Brown, 1968), X. hunaniense (Wang and Wu, 1992) and X. radicicola (Goodey, 1936) by an elongated tail with c′ value more than 4 vs a shorter and conoid shaped tail, c′ value less than 4; from X. brasiliense (Lordello, 1951), X. fagesi (Germani, 1990), and X. ensiculiferum (Cobb, 1893) (Thorne, 1937) by an elongated tail with c′ value more than 4 vs a short round to hemisphere tail with c′ value less than 1.

To help identifying Xiphinema species in group 1, a key was proposed as below:

  1. Tail short round to almost hemisphere with c′<1 ……………………………………….2

    Tail conoid shaped with 1 < c′ < 4……………..….….……….……..…………3

    Tail elongated with c′ > 4………………………….………………..…………….6

  2. Tail ends with a digit………………………….………..…………………X. brasiliense

    Tail ends round and hemispherical…….………..………………..X. ensiculiferum

    Tail ends swollen…………………………………………..……………..X. fagesi

  3. Tail conoid shaped tapers off evenly with c′ = 2.6…………….…… X. monohysterum

    Tail with c′ < 2……………..………….………………….…..……….………….4

  4. Cardia visible………………………………………………………………..X. naturela

    Cardia not visible……………….……………………..…..…….……………….5

  5. Tail tapers off evenly and with hyaline part 20 µm long…..………..……X. radicicola

    Tail tapers off unevenly and without hyaline part………..………….X. hunaniense

  6. Tail very long almost filiform c′ > 7……………………………………..…..X. orthotenum

    Tail elongated with 4 < c′ < 7…………………………….………..…..…………7

  7. Tail straight or bent dorsally……………..…..……………………………… X. winotoi

    Tail bent ventrally……………………..……….………………………………….8

  8. Tail hyaline part > 50 µm long…..………………….………………..X. hangzhouense

    Tail hyaline part < 50 µm long……………………………..……..……………..9

  9. Tail hyaline part < 30 µm long………..………………………….……….X. manasiae

    Tail hyaline part > 30 and <50 µm long………………………………..…..…..10

  10. Cardia weak with wide lumen………………….……………..…X. parachamberi n. sp.

    Cardia strong with narrow lumen…………………………………………X. chambersi

Etymology

The species epithet is formed from the Latin word para = beside or near, and chambersi, thereby reflecting its close similarity to X. chambersi.

Molecular profiles and phylogenetic status

The sequenced fragments of near-full-length 18S, 28S D2/D3 and ITS1 are of ca 1,700bp, 800 bp and 1,000 bp, respectively. DNA sequences of X. parachambersi n. sp. have the highest match with the Xiphinema sequences deposited in GenBank, but with distinct differences, most close to X. chambersi. The near-full-length 18S rRNA (MG786444) from X. parachambersi n. sp. showed a 97 to 98% similarity (differ in 7-34 bps) with X. chambersi, X. ifacolum, X. paritaliae, and X. turcicum. 28S D2/D3 rRNA sequences of X. parachambersi n. sp. (MG786445) showed 80 to 95% similarity (differ in 36-103 bps) with X. chambersi, X. insigne, X. elongatum, X. savanicola, X. setariae, X. vulgare, and X. hangzhouense. The ITS1 rRNA sequence (MG786441-MG786443) of X. parachambersi n. sp. showed 80 to 84% similarity (9–192 bps) and 6 to 9% gaps with X. chambersi.

Phylogenetic relationships among Xiphinema species inferred from analyses of 18S, 28S D2/D3, and ITS1 gene sequences using BI are given in Figures 6, 7, and 8, respectively (Table S1). Near-full-length 18S rRNA gene (Fig. 6), tree was constructed from multiple sequence alignments of 66 sequences. In this tree, the X. parachambersi n. sp. is grouped with X. chambersi with 100% support, with a sister clade formed by morphospecies which belongs to group 4 and 5, i.e. X. ifacolum, X. paritaliae and X. turcicum. Two other species in group 1, i.e. X. brasiliense and X. ensiculiferum are not close to X. parachambersi n. sp.

Table S1

Sequences of nematode species used for the phylogenetic analyses.

10.21307_jofnem-2018-027-t00A1.jpg

The 28S D2/D3 gene tree (Fig. 7), based on a multiple alignment of 85 sequences, revealed two major clades consisting of X. americanum and X. non-americanum group species. X. parachambersi n. sp. is grouped with X. chambersi and X. naturale in group 1 with 100% support. This clade is in a 100% supported monophyletic clade with some other species in morphospecies group 1 and 7, i.e., X. hangzhouense, X. elongatum, X. insigne, X. savanicola, X. setariae, and X. vulgare. Another species in group 1, i.e. X. brasiliense, are not close to X. parachambersi n. sp.

The ITS1 tree (Fig. 8), was constructed from multiple sequence alignments of 68 sequences. In this tree, X. parachambersi n. sp. is in a highly supported monophyletic clade with 12 populations of X. chambersi with 95% support. This clade is sister to some species in morphospecies group 1, i.e., X. hangzhouense, and group 7, i.e., X. hunaniense, X. elongatum, X. setariae, and X. insigne.

Fig. 6

Bayesian consensus tree of Xiphinema parachamberi n. sp. inferred from 18S under GTR+I+G model (-lnL=3332.0762; AIC=6682.1523; freqA=0.1821; freqC=0.209; freqG=0.3285; freqT=0.2804; R(a)=1.4406; R(b)=5.2581; R(c)=2.6656; R(d)=0.7382; R(e)=5.2581; R(f)=1; Pinva=0.2316; Shape=0.4544). Posterior probability values exceeding 50% are given on appropriate clades.

10.21307_jofnem-2018-027-f006.jpg
Fig. 7

Bayesian consensus tree of Xiphinema parachamberi n. sp. inferred from 28S D2/D3 under GTR+I+G model (-lnL=10912.0693; AIC=21844.1387; freqA=0.2463; freqC=0.2277; freqG=0.2969; freqT=0.2291; R(a)=0.9039; R(b)=2.4909; R(c)=2.4092; R(d)=0.4557; R(e)=3.9274; R(f)=1; Pinva=0.3185; Shape=0.782). Posterior probability values exceeding 50% are given on appropriate clades.

10.21307_jofnem-2018-027-f007.jpg
Fig. 8

Bayesian consensus tree of Xiphinema parachamberi n. sp. inferred from ITS1 under GTR+I+G model (-lnL=19846.0566; AIC=39712.1133; freqA=0.2723; freqC=0.2059; freqG=0.2672; freqT=0.2547; R(a)=0.851; R(b)=3.6772; R(c)=1.3471; R(d)=0.6487; R(e)=5.209; R(f)=1; Pinva=0.0808; Shape=1.2786). Posterior probability values exceeding 50% are given on appropriate clades.

10.21307_jofnem-2018-027-f008.jpg

Discussion

Mono-opisthodelphic dagger nematodes in the genus Xiphinema belongs to morphospecies group 1. This morphospecies group comprises species with anterior genital branch completely absent to a very small post uterine sac. Among 12 species in this group, i.e., X. brasiliense, X. chambersi, X. ensiculiferum, X. fagesi, X. hunaniense, X. hangzhouense, X. monasiae, X. monohysterum, X. naturale, X. orthotenum, X. radicicola and X. winotoi (Loof and Luc, 1993; Loof et al., 1996; Cai et al., 2018), only a few species were described with molecular characterizations. This study added another species with complete morphological and molecular characterization, which will help to enhance the knowledge and understanding to the classification of this group of nematodes. The diagnostic value of the apparently unique cardia in this new species is still unclear as few species were studied with this structure. The function of cardia is proposed to prevent the regurgitation of the food, however, at this point, we can only assume that sheath-less cardia could be primitive to cardia with sheath.

Our phylogenetic studies suggested that species in the morphospecies group 1 are not monophyletic, and morphospecies grouping was only established for the convenience of identification and do not always reflect the evolutionary history, which is consistent with other studies (Handoo et al., 2016; Cai et al., 2018). Considering the high variability in the morphological characters in Xiphinema species, it is necessary to use integrated morphological and molecular approaches in species diagnosis, especially in making a regulatory decision regarding the movement of soil and plant material.

Morphospecies group 1 species are mainly distributed in Brazil (Oliveira et al., 2003; Silva et al., 2008; De Jesus et al., 2015), China (Zeng et al., 2016), USA, Canada (Ye, 2002; Yu et al., 2010), Malaysia (Rahman-Razak and Loof, 1998), France (Luc and Coomans, 1992) and India (Loof et al., 2001). This new species is described from the ornamental plants imported from Japan, which represents the first group 1 species from this country.

Acknowledgements

The research was supported by Ningbo Science and Technology Innovation Team (2015C110018) China Customs Science Program (2016IK168,2017IK299 and 2018IK055).

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  10. Ebsary, B.A., Vrain, T.C., and Graham, M.B.. 1989. Two new species of Xiphinema (Nematoda: Longidorinae) from British Columbia vineyard. Canadian Journal of Zoology 67: 801–804.
    [CROSSREF]
  11. Ferris, V.R., Ferris, J.M., and Faghihi, J.. 1993. Variation in spacer ribosomal DNA in some cyst forming species of plant parasitic nematodes. Fundamental and Applied Nematology 16: 177–184.
  12. Germani, G.. 1990. Description of Dolichodorus pellegrinensis sp. n. (Nematoda: Dolichodoridae) and Xiphinema fagesi sp. n. (Nematoda: Dorylaimidae) from New Caledonia. Nematologica 36: 73–80.
    [CROSSREF]
  13. Goodey, T.. 1936. A new dorylaimid nematode, Xiphinema radicicola sp. n. Journal of Helminthology 14: 69–72.
    [CROSSREF]
  14. Handoo, Z.A., Carta, L.K., Skantar, A.M., Subbotin, S.A., and Fraedrich, S.S.. 2016. Molecular and morphological characterization of a Xiphinema chambersi population from live oak trees in Jekyll Island, Georgia, with a re-description of the species and comments on its morphometric variations. Journal of Nematology 48: 20–27.
    [CROSSREF]
  15. Huelsenbeck, J.P., and Ronquist, F.. 2001. Mr Bayes: Bayesian inference of phylogenetic trees. Bioinformatics 17: 1754–1755.
    [CROSSREF]
  16. Hunt, D.J.. 1993. Aphelenchida, longidoridae and trichodoridae: their systematics and bionomics, CABI Publishing, Wallingford, UK, 352 pp.
  17. Kumar, S., Stecher, G., and Tamura, K.. 2016. MEGA7: molecular evolutionary genetics analysis version 7.0 for bigger datasets. Molecular Biology and Evolution 33: 1870–1874.
    [CROSSREF]
  18. Lamberti, F., and Bleve-Zacheo, T.. 1979. Studies on Xiphinema americanum sensu lato with description of fifteen new species (Nematoda: Longidoridae). Nematologica Mediterranea 7: 51–106.
  19. Lamberti, F., De Luca, F., Molinari, S., Duncan, L.W., Agostinelli, A., Coiro, M.I., Dunn, D., and Radicci, V.. 2002. Xiphinema chambersi and Xiphinema naturale sp. n., two opisthodelphic Longidorids (Nematoda, Dorylaimida) from Florida. Nematologica Mediterranea 30: 3–10.
  20. Larget, B., and Simon, D.L.. 1999. Markov Chain Monte Carlo algorithms for the Bayesian analysis of phylogenetic trees. Molecular Biology and Evolution 16: 750–759.
    [CROSSREF]
  21. Li, H., Trinh, P.Q., Waeyenberge, L., and Moens, M.. 2008. Bursaphelenchus chengi sp. n. (Nematoda: Parasitaphelenchidae) isolated at Nanjing, China, in packaging wood from Taiwan. Nematology 10: 335–346.
    [CROSSREF]
  22. Loof, P.A.A., and Luc, M.. 1990. A revised polytomous key for the identification of species of the genus Xiphinema Cobb, 1913 (Nematoda: Longidoridae) with exclusion of the Xiphinema americanum-group. Systematic Parasitology 16: 35–66.
    [CROSSREF]
  23. Loof, P.A.A., and Luc, M.. 1993. A revised polytomous key for the identification of species of the genus Xiphinema Cobb, 1913 (Nematoda: Longidoridae) with exclusion of the X. americanum-group: Supplement 1. Systematic Parasitology 24: 185–189.
    [CROSSREF]
  24. Loof, P.A.A., Coomans, A., Baujard, P., and Luc, M.. 2001. On five species of the genus Xiphinema Cobb, 1913 (Nematoda: Longidoridae) recently described from India. Nematology 3: 277–283.
    [CROSSREF]
  25. Loof, P.A.A., Luc, M., and Baujard, P.. 1996. A revised polytomous key for the identification of species of the genus Xiphinema Cobb, 1913 (Nematoda: Longidoridae) with exclusion of the X. americanum-group: Supplement 2. Systematic Parasitology 33: 23–29.
  26. Lordello, L.G.E.. 1951. Xiphinema brasiliense, nova espécie de nematoide do Brasil, parasita de Solanum tuberosum L. Bragantia 11: 87–90.
    [CROSSREF]
  27. Luc, M., and Coomans, A.. 1992. Plant parasitic nematodes of the genus Xiphinema (Longidoridae) in Guiana and Martinique. Belgian Journal of Zoology 122: 147–183.
  28. Meyl, A.H.. 1953. Beitrage zur Kenntnis der Nematodenfauna vulkanisch erhitzter Biotope. 1. Mitt., Die Terrikolen Nematoden in Bereich von Fumarolen auf der Insel Ischia. Zeitschrift fuer Morphologie und Okologie der Tiere 42: 67–116.
    [CROSSREF]
  29. Micoletzky, H.. 1927. Xiphinema diversicaudatuam. C.I.H. Descriptions of plant parasitic nematodes Set 4, No.6. Farnham Royal, UK, Commonwealth Agricultural Bureaux.
  30. Oliveira, C.M., Brown, D.J.F., Neilson, R., Monteiro, A.R., Ferraz, L.C.C., and Lamberti, F.. 2003. The occurrence and geographic distribution of Xiphinema and Xiphidorus species (Nematoda: Longidoridae) in Brazil. Helminthologia 40: 41–54.
  31. Palomares-Rius, J.E., Cantalapiedra-Navarreste, C., Archidona-Yuste, A., Subbotin, S.A., and Castillo, P.. 2017. The utility of mtDNA and rDNA for barcoding and phylogeny of plant-parasitic nematodes from Longidoridae (Nematoda, Enoplea). Scientific Reports 7: 10905.
    [CROSSREF]
  32. Penas, A.C., Metge, K., Mota, M., and Valadas, V.. 2006. Bursaphelenchus antoniae sp. n. (Nematoda: Parasitaphelenchidae) associated with Hylobius sp. from Pinus pinaster in Portugal. Nematology 8: 659–669.
    [CROSSREF]
  33. Posada, D., and Criandall, K.A.. 1998. Modeltest: testing the model of DNA substitution. Bioinformatics 14: 817–818.
    [CROSSREF]
  34. Rahman-Razak, A., and Loof, P.A.A.. 1998. The genus Xiphinema Cobb, 1913 (Nematoda: Longidoridae) in western Malaysia. Fundamentals of Applied Nematology 21: 413–428.
  35. Seinhorst, J.W.. 1959. A rapid method for the transfer of nematodes from fixative to anhydrous glycerin. Nematologica 4: 67–69.
    [CROSSREF]
  36. Silva, R.A., Silva, E.S., Antedomenico, S.R. and Inomoto, M.M.. 2008. Fauna of phytonematodes in the Atlantic forest from Ribeira Valley, Sao Paulo State, Brazil. Nematropica 38: 1–12.
  37. Sen, D., Chatterjee, A., and Manna, B.. 2010. A new and a known species of Xiphinema Cobb, 1913 (Dorylaimida: Xiphinematidae) from West Bengal, India with a key to the mono-opisthodelphic species of the genus. Nematologica Mediterranea 38: 187–195.
  38. Thorne, G.. 1937. Notes on free living and plant-parasitic nematodes.III. Proceedings of the Helminthological Society Washington 4: 16–18.
  39. Thorne, G.. 1939. A monograph of the nematodes of the superfamily Dorylaimoidea. Capita Zoologica 8: 261, pp.
  40. Thorne, G., and Allen, M.W.. 1950. Paratylenchus hamatus sp. n. and Xiphinema index sp. n., two nematodes associated with fig roots with a note on Paratylenchus anceps Cobb. Proceedings of the Helminthological Society of Washington 17: 27–35.
  41. Wang, S., and Wu, X.. 1992. Two species of Xiphinema Cobb, 1913 (Dorylaimida, Longidoridae) from around grape roots in China. Acta Phytopathologica Sinica 22: 117–123.
  42. Ye, W.. 2002. Morphological and molecular taxonomy of Longidorus and Xiphinema (Nematoda: Longidoridae) occurring in Arkansas, USA. Ph.D. dissertation, University of Arkansas, Fayetteville, Arkansas.
  43. Ye, W., Giblin-Davis, R.M., Braasch, H., Morris, K., and Thomas, W.K.. 2007. Phylogenetic relationships among Bursaphelenchus species (Nematoda: Parasitaphelenchidae) inferred from nuclear ribosomal and mitochondrial DNA sequence data. Molecular Phylogenetics and Evolution 43: 1185–1197.
    [CROSSREF]
  44. Yu, Q., Badiss, A., Zhang, Z., and Ye, W.. 2010. First report and morphological, molecular characterization of Xiphinema chambersi Thorne, 1939 (Nematoda, Longidoridae) in Canada. ZooKeys 49: 13–22.
    [CROSSREF]
  45. Zeng, Y., Ye, W., Zhang, Z., Sun, H., Yong, L., Huang, Y., Zhao, K., Liang, H., and Kerns, J.. 2016. Morphological and molecular characterization of Xiphinema species from Shenzhen, China. Helminthologica 53: 62–75.
    [CROSSREF]
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FIGURES & TABLES

Fig. 1

Line drawings of Xiphinema parachamberi n. sp. female. A: Esophageal region; B: Esophageal bulb; C: Entire body; D: Genital branch; E: Tail region (Scale bars: A, E = 40; B, C=20, D=100 μm).

Full Size   |   Slide (.pptx)

Fig. 2

Light photomicrographs of Xiphinema parachamberi n. sp. female. A: Anterior region, arrow showing position of vulva (v); B: Lip region; C-E: Esophageal bulb (arrows showing different position of gland nuclei); F: Esophago-intestinal junction arrows pointing the base of pharyngeal bulb and cardia. G: Vulval region; H, I: Gonad; J: Female tail (arrows showing position of (a) anus and caudal pores); K, L: Female tail (arrows showing position of (a) anus) (Scale bars: A, L = 10 μm).

Full Size   |   Slide (.pptx)

Fig. 3

Light photomicrographs of cardia of Xiphinema parachamberi n. sp. Scale bars: A–C=20 μm).

Full Size   |   Slide (.pptx)

Fig. 4

Light photomicrographs of Xiphinema parachamberi n. sp. juveniles and female. A–D: Anterior regions of J2/J3, J3/J4 and female; E–H: Tail regions of J2/J3, J3/J4 and female (arrows showing position of anus (a)) (Scale bars: A–L = 10 μm).

Full Size   |   Slide (.pptx)

Fig. 5

Relationship of body length to length of functional and replacement odontostyle (Ost and rOst, respectively); length in two juvenile developmental stages and mature females of Xiphinema parachambersi n. sp.

Full Size   |   Slide (.pptx)

Fig. 6

Bayesian consensus tree of Xiphinema parachamberi n. sp. inferred from 18S under GTR+I+G model (-lnL=3332.0762; AIC=6682.1523; freqA=0.1821; freqC=0.209; freqG=0.3285; freqT=0.2804; R(a)=1.4406; R(b)=5.2581; R(c)=2.6656; R(d)=0.7382; R(e)=5.2581; R(f)=1; Pinva=0.2316; Shape=0.4544). Posterior probability values exceeding 50% are given on appropriate clades.

Full Size   |   Slide (.pptx)

Fig. 7

Bayesian consensus tree of Xiphinema parachamberi n. sp. inferred from 28S D2/D3 under GTR+I+G model (-lnL=10912.0693; AIC=21844.1387; freqA=0.2463; freqC=0.2277; freqG=0.2969; freqT=0.2291; R(a)=0.9039; R(b)=2.4909; R(c)=2.4092; R(d)=0.4557; R(e)=3.9274; R(f)=1; Pinva=0.3185; Shape=0.782). Posterior probability values exceeding 50% are given on appropriate clades.

Full Size   |   Slide (.pptx)

Fig. 8

Bayesian consensus tree of Xiphinema parachamberi n. sp. inferred from ITS1 under GTR+I+G model (-lnL=19846.0566; AIC=39712.1133; freqA=0.2723; freqC=0.2059; freqG=0.2672; freqT=0.2547; R(a)=0.851; R(b)=3.6772; R(c)=1.3471; R(d)=0.6487; R(e)=5.209; R(f)=1; Pinva=0.0808; Shape=1.2786). Posterior probability values exceeding 50% are given on appropriate clades.

Full Size   |   Slide (.pptx)

Full Size   |   Slide (.pptx)

Full Size   |   Slide (.pptx)

REFERENCES

  1. Brown, R.H.. 1968. Xiphinema monohysterum n. sp. (Nematoda: Dorylaimoidea) from Southern New South Wales. Nematologica 13: 633–637.
    [CROSSREF]
  2. Cai, R., Maria, M., Barsalote, E.M., Subbotin, S.A., and Zheng, J.. 2018. Description of Xiphinema hangzhouense sp. n. (Nematoda: Longidoridae) found from the rhizosphere of Magnolia grandiflora in Hangzhou, Zhejiang Province, China. Nematology 20: 67–80.
    [CROSSREF]
  3. Cherry, T., Szalanski, A.L., Todd, T.C., and Powers, T.O.. 1997. The internal transcribed spacer region of Belonolaimus (Nemata: Belonolaimidae). Journal of Nematology 29: 23–29.
  4. Cobb, N.A.. 1913. New nematode genera found inhabiting fresh water and non-brackish soils. Journal of the Washington Academy of Sciences 3: 432–444.
    [CROSSREF]
  5. Dalmasso, A.. 1969. Etude anatomique et taxonomique des genres Xiphinema, Longidorus et Paralongidorus (Nematoda: Dorylaimidae) Memoires du Museum National d'Histoire Naturelle. Paris, Serie A. Zoologie 61: 33–82.
  6. De Jesus, D.S., de Oliveira, C.M.G., Gastauer, M., and Alexander, C.. 2015. Longidorids from Minas Gerais State, Brazil, with focus on the morphometric variability of Xiphinema krugi (Nematoda: Longidoridae) populations. Tropical Plant Pathology 40: 88–101.
    [CROSSREF]
  7. De Ley, P., Félix, M.A., Frisse, L.M., Nadler, S.A., Sternberg, P.W., and Thomas, W.K.. 1999. Molecular and morphological characterisation of two reproductively isolated species with mirror-image anatomy (Nematoda: Cephalobidae). Nematology 1: 591–612.
    [CROSSREF]
  8. Decraemer, W., and Hunt, D.J.. 2006. Structure and classification. in Perry, R.N., and Moens, M. (eds). Plant Nematology, CABI Publishing, Wallingford, UK: 3–32.
  9. Decraemer, W., and Robbins, R.T.. 2007. The who, what and where of Longidoridae and Trichodoridae. Journal of Nematology 39: 295–297.
    [PUBMED]
  10. Ebsary, B.A., Vrain, T.C., and Graham, M.B.. 1989. Two new species of Xiphinema (Nematoda: Longidorinae) from British Columbia vineyard. Canadian Journal of Zoology 67: 801–804.
    [CROSSREF]
  11. Ferris, V.R., Ferris, J.M., and Faghihi, J.. 1993. Variation in spacer ribosomal DNA in some cyst forming species of plant parasitic nematodes. Fundamental and Applied Nematology 16: 177–184.
  12. Germani, G.. 1990. Description of Dolichodorus pellegrinensis sp. n. (Nematoda: Dolichodoridae) and Xiphinema fagesi sp. n. (Nematoda: Dorylaimidae) from New Caledonia. Nematologica 36: 73–80.
    [CROSSREF]
  13. Goodey, T.. 1936. A new dorylaimid nematode, Xiphinema radicicola sp. n. Journal of Helminthology 14: 69–72.
    [CROSSREF]
  14. Handoo, Z.A., Carta, L.K., Skantar, A.M., Subbotin, S.A., and Fraedrich, S.S.. 2016. Molecular and morphological characterization of a Xiphinema chambersi population from live oak trees in Jekyll Island, Georgia, with a re-description of the species and comments on its morphometric variations. Journal of Nematology 48: 20–27.
    [CROSSREF]
  15. Huelsenbeck, J.P., and Ronquist, F.. 2001. Mr Bayes: Bayesian inference of phylogenetic trees. Bioinformatics 17: 1754–1755.
    [CROSSREF]
  16. Hunt, D.J.. 1993. Aphelenchida, longidoridae and trichodoridae: their systematics and bionomics, CABI Publishing, Wallingford, UK, 352 pp.
  17. Kumar, S., Stecher, G., and Tamura, K.. 2016. MEGA7: molecular evolutionary genetics analysis version 7.0 for bigger datasets. Molecular Biology and Evolution 33: 1870–1874.
    [CROSSREF]
  18. Lamberti, F., and Bleve-Zacheo, T.. 1979. Studies on Xiphinema americanum sensu lato with description of fifteen new species (Nematoda: Longidoridae). Nematologica Mediterranea 7: 51–106.
  19. Lamberti, F., De Luca, F., Molinari, S., Duncan, L.W., Agostinelli, A., Coiro, M.I., Dunn, D., and Radicci, V.. 2002. Xiphinema chambersi and Xiphinema naturale sp. n., two opisthodelphic Longidorids (Nematoda, Dorylaimida) from Florida. Nematologica Mediterranea 30: 3–10.
  20. Larget, B., and Simon, D.L.. 1999. Markov Chain Monte Carlo algorithms for the Bayesian analysis of phylogenetic trees. Molecular Biology and Evolution 16: 750–759.
    [CROSSREF]
  21. Li, H., Trinh, P.Q., Waeyenberge, L., and Moens, M.. 2008. Bursaphelenchus chengi sp. n. (Nematoda: Parasitaphelenchidae) isolated at Nanjing, China, in packaging wood from Taiwan. Nematology 10: 335–346.
    [CROSSREF]
  22. Loof, P.A.A., and Luc, M.. 1990. A revised polytomous key for the identification of species of the genus Xiphinema Cobb, 1913 (Nematoda: Longidoridae) with exclusion of the Xiphinema americanum-group. Systematic Parasitology 16: 35–66.
    [CROSSREF]
  23. Loof, P.A.A., and Luc, M.. 1993. A revised polytomous key for the identification of species of the genus Xiphinema Cobb, 1913 (Nematoda: Longidoridae) with exclusion of the X. americanum-group: Supplement 1. Systematic Parasitology 24: 185–189.
    [CROSSREF]
  24. Loof, P.A.A., Coomans, A., Baujard, P., and Luc, M.. 2001. On five species of the genus Xiphinema Cobb, 1913 (Nematoda: Longidoridae) recently described from India. Nematology 3: 277–283.
    [CROSSREF]
  25. Loof, P.A.A., Luc, M., and Baujard, P.. 1996. A revised polytomous key for the identification of species of the genus Xiphinema Cobb, 1913 (Nematoda: Longidoridae) with exclusion of the X. americanum-group: Supplement 2. Systematic Parasitology 33: 23–29.
  26. Lordello, L.G.E.. 1951. Xiphinema brasiliense, nova espécie de nematoide do Brasil, parasita de Solanum tuberosum L. Bragantia 11: 87–90.
    [CROSSREF]
  27. Luc, M., and Coomans, A.. 1992. Plant parasitic nematodes of the genus Xiphinema (Longidoridae) in Guiana and Martinique. Belgian Journal of Zoology 122: 147–183.
  28. Meyl, A.H.. 1953. Beitrage zur Kenntnis der Nematodenfauna vulkanisch erhitzter Biotope. 1. Mitt., Die Terrikolen Nematoden in Bereich von Fumarolen auf der Insel Ischia. Zeitschrift fuer Morphologie und Okologie der Tiere 42: 67–116.
    [CROSSREF]
  29. Micoletzky, H.. 1927. Xiphinema diversicaudatuam. C.I.H. Descriptions of plant parasitic nematodes Set 4, No.6. Farnham Royal, UK, Commonwealth Agricultural Bureaux.
  30. Oliveira, C.M., Brown, D.J.F., Neilson, R., Monteiro, A.R., Ferraz, L.C.C., and Lamberti, F.. 2003. The occurrence and geographic distribution of Xiphinema and Xiphidorus species (Nematoda: Longidoridae) in Brazil. Helminthologia 40: 41–54.
  31. Palomares-Rius, J.E., Cantalapiedra-Navarreste, C., Archidona-Yuste, A., Subbotin, S.A., and Castillo, P.. 2017. The utility of mtDNA and rDNA for barcoding and phylogeny of plant-parasitic nematodes from Longidoridae (Nematoda, Enoplea). Scientific Reports 7: 10905.
    [CROSSREF]
  32. Penas, A.C., Metge, K., Mota, M., and Valadas, V.. 2006. Bursaphelenchus antoniae sp. n. (Nematoda: Parasitaphelenchidae) associated with Hylobius sp. from Pinus pinaster in Portugal. Nematology 8: 659–669.
    [CROSSREF]
  33. Posada, D., and Criandall, K.A.. 1998. Modeltest: testing the model of DNA substitution. Bioinformatics 14: 817–818.
    [CROSSREF]
  34. Rahman-Razak, A., and Loof, P.A.A.. 1998. The genus Xiphinema Cobb, 1913 (Nematoda: Longidoridae) in western Malaysia. Fundamentals of Applied Nematology 21: 413–428.
  35. Seinhorst, J.W.. 1959. A rapid method for the transfer of nematodes from fixative to anhydrous glycerin. Nematologica 4: 67–69.
    [CROSSREF]
  36. Silva, R.A., Silva, E.S., Antedomenico, S.R. and Inomoto, M.M.. 2008. Fauna of phytonematodes in the Atlantic forest from Ribeira Valley, Sao Paulo State, Brazil. Nematropica 38: 1–12.
  37. Sen, D., Chatterjee, A., and Manna, B.. 2010. A new and a known species of Xiphinema Cobb, 1913 (Dorylaimida: Xiphinematidae) from West Bengal, India with a key to the mono-opisthodelphic species of the genus. Nematologica Mediterranea 38: 187–195.
  38. Thorne, G.. 1937. Notes on free living and plant-parasitic nematodes.III. Proceedings of the Helminthological Society Washington 4: 16–18.
  39. Thorne, G.. 1939. A monograph of the nematodes of the superfamily Dorylaimoidea. Capita Zoologica 8: 261, pp.
  40. Thorne, G., and Allen, M.W.. 1950. Paratylenchus hamatus sp. n. and Xiphinema index sp. n., two nematodes associated with fig roots with a note on Paratylenchus anceps Cobb. Proceedings of the Helminthological Society of Washington 17: 27–35.
  41. Wang, S., and Wu, X.. 1992. Two species of Xiphinema Cobb, 1913 (Dorylaimida, Longidoridae) from around grape roots in China. Acta Phytopathologica Sinica 22: 117–123.
  42. Ye, W.. 2002. Morphological and molecular taxonomy of Longidorus and Xiphinema (Nematoda: Longidoridae) occurring in Arkansas, USA. Ph.D. dissertation, University of Arkansas, Fayetteville, Arkansas.
  43. Ye, W., Giblin-Davis, R.M., Braasch, H., Morris, K., and Thomas, W.K.. 2007. Phylogenetic relationships among Bursaphelenchus species (Nematoda: Parasitaphelenchidae) inferred from nuclear ribosomal and mitochondrial DNA sequence data. Molecular Phylogenetics and Evolution 43: 1185–1197.
    [CROSSREF]
  44. Yu, Q., Badiss, A., Zhang, Z., and Ye, W.. 2010. First report and morphological, molecular characterization of Xiphinema chambersi Thorne, 1939 (Nematoda, Longidoridae) in Canada. ZooKeys 49: 13–22.
    [CROSSREF]
  45. Zeng, Y., Ye, W., Zhang, Z., Sun, H., Yong, L., Huang, Y., Zhao, K., Liang, H., and Kerns, J.. 2016. Morphological and molecular characterization of Xiphinema species from Shenzhen, China. Helminthologica 53: 62–75.
    [CROSSREF]

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