Xiphinema

Xiphinema Cobb

Family Longidoridae (ref. ID; 6168, 6182, 7647)

ref. ID; 1923

Stylet very long with extensions long and flanged. (Usually parasitic on roots of terrestrial plants, about 15 species) (ref. ID; 1923)

ref. ID; 6691

Plant parasites. (ref. ID; 6691)

Xiphinema americanum Cobb, 1913 (ref. ID; 6556, 7209, 7647)
Xiphinema brevicolle Lordello & Da Costa (ref. ID; 6556)
Xiphinema bricolensis Ebsary, Vrain & Graham, 1989 (ref. ID; 6556 original paper)
Xiphinema californicum Lamberti & Bleve-Zacheo, 1979 (ref. ID; 6556)
Xiphinema citricolum Lamberti & Bleve-Zacheo (ref. ID; 6556)
Xiphinema diffusum Lamberti & Bleve-Zacheo (ref. ID; 6556)
Xiphinema floridae Lamberti & Bleve-Zacheo (ref. ID; 6556)
Xiphinema georgianumm Lamberti & Bleve-Zacheo (ref. ID; 6556)
Xiphinema intermedium Lamberti & Bleve-Zacheo (ref. ID; 6556)
Xiphinema laevistriatum Lamberti & Bleve-Zacheo (ref. ID; 6556)
Xiphinema neoamericanum Saxena, Chhabra & Joshi (ref. ID; 7647 original paper)
Xiphinema occiduum Ebsary, Potter & Allen, 1984 (ref. ID; 7209 original paper), Ebsary et al. (ref. ID; 6556)
Xiphinema pacificum Ebsary, Vrain & Graham, 1989 (ref. ID; 6556 original paper)
Xiphinema rivesi Dalmasso, 1969 (ref. ID; 6556, 7209)
Xiphinema tarjanense Lamberti & Bleve-Zacheo (ref. ID; 6556)
Xiphinema tenuicutis Lamberti & Bleve-Zacheo (ref. ID; 6556)
Xiphinema thornei Lamberti & Golden (ref. ID; 6556)
Xiphinema utahense Lamberti & Bleve-Zacheo (ref. ID; 6556)

Xiphinema americanum Cobb, 1913 (ref. ID; 6556, 7209, 7647)

Descriptions

Female: Body in an open spiral. Head set off by a distinct constriction. Exocuticle smooth, endocuticle finely striated. Odontostyle and odontophore robust with flanges of odontophore 7-8 µm wide. Vagina about 50% of body width. Ovaries opposed, reflexed. Rectum about one anal body width. Tail dorsally convex, finely rounded with two caudal pores. (ref. ID; 7209)

Male: None found. (ref. ID; 7209)

Xiphinema bricolensis Ebsary, Vrain & Graham, 1989 (ref. ID; 6556 original paper)

Differential diagnosis

Xiphinema bricolensis is most similar to X. rivesi, X. occiduum, and X. thornei. It differs from X. rivesi by having a set-off head, greater a value (54 versus 49), and a more anterior guiding ring (mean less than 71 µm versus more than 74 µm). Xiphinema bricolensis females differ from those X. occiduum by having mean odontostyle length greater than 83 µm versus less than 78 µm, longer female tail (mean of more than 33 µm versus mean less than 32 µm), mean a value less than 56 versus more than 58, mean c value less than 65 versus more than 65, mean c' value of more than 1.4 versus less than 1.3. Xiphinema bricolensis females differ from those of X. thornei by having a smaller c value (55-61 versus 62-71), larger c' value (1.3-1.5 versus 1.2-1.3), and longer tail (33-37 versus 29-32 µm). (ref. ID; 6556)

Descriptions

Female: Body in an open spiral. Exocuticle smooth, endocuticle with fine transverse striae. Head 11 µm wide, set off from body by a moderate constriction. Amphids stirrup shaped, aperture two-thirds head width. Esophageal nuclei obscure, base of esophagus 63-70 µm long. Intestine without significant characteristics. Cardia conoid truncate. Vulva a simple transverse slit. Vagina about one-half body width. Spermatheca devoid of sperm. Genital branches with similar structure and approximate equal length, each branch occupying about 6-9% of total body. Ovaries reflexed. Rectum 13-18 µm long. Prerectum 60-155 µm (110; SD 32 µm) long. Tail dorsally convex, ventrally straight, terminus conoid rounded. J length 6-7 µm, J width 8.5-9.5 µm. Two pairs of caudal papillae near midtail region. (ref. ID; 6556)

Male: Rare, similar to female. Spicules well sclerotized. Supplements consisting of an adanal pair 7 µm anterior to anus, preceded by an anterior series of 11 supplements. Prerectum 200 µm long. (ref. ID; 6556)

Remarks

The distribution of X. occiduum reported by Ebsary et al. (1984) is hereby emended. All specimens from Alberta, Saskatchewan, and Manitoba were reexamined and are confirmed as X. occiduum s.s. All specimens from British Columbia are X. bricolensis n. sp. This distribution, together with the data supplied by Graham et al. (1989), indicates that X. bricolensis is widespread throughout the Okanagan and Similkameen valleys of British Columbia. (ref. ID; 6556)

Type host and locality

Collected June 1955 by R.H. Mulvey from the rhizosphere of apple tree roots at Vernon, British Columbia. (ref. ID; 6556)

Type deposition

Holotype female and allotype male mounted on slide 426 and deposited in the Canadian National Collection of Nematodes (CNCN) Ottawa. Nineteen female paratypes mounted on slides 426a-e and deposited as follows: 11 in the CNCN and 4 each with United States Department of Agriculture (USDA) Nematode Collection, Beltsville, Maryland, and Lavoratoire des vers, Museum National d'Histoire Naturelle, Paris, France. (ref. ID; 6556)

Measurements

Holotype (female): L=1.9 mm, a=60, b=6.5, c=54, c'=1.3, V=51; odontostyle 88 µm, odontophore 52 µm, guiding ring from head apex (GR) 66 µm. (ref. ID; 6556)

Allotype (male): L=2.1 mm, a=56, b=6.8, c=56, c'=1.4, opdontostyle 87 µm, odontophore 51 µm, GR=65 µm, spicules 39 µm, tail length 37 µm, anal body width 26 µm, length hyaline portion of tail (J) 4 µm, J width 6 µm. (ref. ID; 6556)

Paratype (female): N=19; L=1.7-2.3 mm (1.9; SD 142 µm), a=52-62(56; SD 3.1), b=6.3-9.5(7.5; SD 0.51), c=49-65(57; SD 4.5), c'=1.3-1.6(1.5; SD 0.15), V=50-55(52; SD 1.2), odontostyle 85-94(87; SD 2.1) µm, odontophore 47-56(51; SD 1.5) µm, GR=61-76(68; SD 2.3) µm, tail length 31-41(36; SD 3.2) µm, anal body width 23-29(25; SD 1.05) µm. (ref. ID; 6556)

Other populations:

Covert Vineyard (females) N=15: L=1.7-2.1 mm (1.9; SD 142 µm), a=49-62(54; SD 4.2), b=6.5-8.6(7.2; SD 0.68), c=45-64(56; SD 5.6), c'=1.3-1.8(1.5; SD 0.17), V=50-54.5(52; SD 1.6), odontosylte 79-90(85; SD 3.3) µm, odontophore 49-52(50; SD 0.94) µm, GR=74-79(76; SD 1.8) µm, tail length 31-40(34; SD 3.2) µm, anal body width 22-25(23; SD 1) µm. (ref. ID; 6556)
Screbuck Vineyard (females) N=10: L=1.8-2.0 mm (1.9; SD 72 µm), a=47-62(54; SD 3.9), b=6-7.1(6.2; SD 0.43), c=47-58(52; SD 3.3), c'=1.4-1.7(1.6; SD 0.1), V=50-54(52; SD 1.04), odontostyle 79-87(83; SD 2.9) µm, odontophore 49-54(52; SD 1.5) µm, GR=68-74(71; SD 2.8) µm, tail length 31-40(36; SD 2.9) µm, anal body width 2-25(23; SD 1.02) µm. (ref. ID; 6556)

Xiphinema neoamericanum Saxena, Chhabra & Joshi (ref. ID; 7647 original paper)

Diagnosis and relationship

With the general description and measurements, Xiphinema neoamericanum sp. n. comes close to X. americanum Cobb, 1913 but differs from it in the continuous lip region and a convex conoid tail with a subacute terminus. (ref. ID; 7647)

Descriptions

When relaxed in hot water the eelworm gets ventrally curved usually in a full circle. Body tapering at both the ends, cuticle exceptionally thick in the region of head and tail. Lip region low, rounded, not set-off. Spear attenuated 70 µm in length, spear extension 40 µm in length. Guiding ring located at the base of the spear. Oesophagus with an anterior tubular non-muscular part followed by an off-set bulb which contains all the 5 oesophageal gland nuclei. Nerve ring about a body-width behind the base of spear-extension. Hemizonid not visible. Oesophago-intestinal junction with a conoid-rounded valve. Vulva in the form of a transverse slit. Vagina reaching half vulva-body width into body. Gonads didelphic, apposed, reflexed at the oviduct. Oocytes arranged in 2 rows at the zone of multiplication. Rectum less hahn one anal-body width long. Tail convex conoid with a sub-acute terminus, about as long as the anal-body width with two pairs of caudal pores. (ref. ID; 7647)

Male: Unknown. (ref. ID; 7647)

Type habitat

Soil around roots of peaches, Prunus persica Stokes. (ref. ID; 7647)

Type locality

Ludhiana campus of Punjab Agricultural University. (ref. ID; 7647)

Type material

Holotype on slide No. Nem. 9 deposited with the Department of Zoology-Entomology, PAU, Ludhiana. Paratypes on slide Nos. Nem. 10-11 deposited as above. (ref. ID; 7647)

Measurements

Holotype (female): L=1.62 mm, a=40.6, b=5.8, c=27, V=50, spear 70 µm, spear extension 40 µm. (ref. ID; 7647)

Paratypes (females n=3): L=1.6-2.05(1.76) mm, a=40-45(42.7), b=5.8-6.5(6.1), c=27-29(28), V=50-52(51), spear 70-72(71) µm, spear extension 40-42(41) µm. (ref. ID; 7647)

Xiphinema occiduum Ebsary, Potter & Allen, 1984 (ref. ID; 7209 original paper), Ebsary et al. (ref. ID; 6556)

Differential diagnosis

Xiphinema occiduum n. sp. is most similar to X. utahense Lambeti and Bleve-Zacheo (1979) but differs significantly by the shorter odontostyle (75(66-82) µm versus 93(87-100) µm), greater J length and width (7(5-11) µm versus 5(3-7) µm and 11(10-14) µm versus 8(6.5-10.5) µm, respectively), more anterior guiding ring (64(56-68) µm versus 81(77-82) µm from oral aperture), a smaller a value (54(50-58) versus 63(60-67)), and a less elongate tail. Xiphinema occiduum is also similar to X. rivesi and X. americanum. It differs from X. rivesi by the set off head, the a value being greater than 50, a more anteriorly placed guiding ring (mean less than 71 µm versus mean of more than 70 µm from oral aperture), by the shorter odontostyle (mean length less than 85 µm versus mean length of more than 88 µm in X. rivesi). Xiphinema occiduum differs from X. americanum by having greater body length, larger c value (greater than 55 versus less than 50 in americanum), smaller mean c' value (less than 1.5 versus more than 1.6 in americanum), wider anal body width (mean 23-28 µm versus 20-21 µm), a greater J width (11-12 µm versus 7-8 µm), and a distinctly more rounded tail. (ref. ID; 7209)

Descriptions

Female: Body in an open spiral. Head 10-11 µm wide, set off from body by a distinct constriction. Amphids typical of the genus, about three quarters of head width. Exocuticle and endocuticle finely striated. Odontostyle and odontophore robust. Flanges of odontophore 6-8 µm wide. A 2- to 3-µm mucro may be present in the anterior portion of the esophageal isthmus. Esophageal gland nuclei obscure. Basal portion of esophagus about 70 µm long. Cardia conoid rounded. Vagina one-third to one-half body width. Ovaries opposed, reflexed. Rectum about one anal body width. Tail dorsally convex, terminus rounded. Two pairs of caudal pores present. (ref. ID; 7209)

Male: Similar to female. Spicules well sclerotized. Supplements consisting of an adanal pair 9 µm anterior to anus preceeded by an anterior series of 9 supplements. (ref. ID; 7209)

Remarks

It should be noted that the populations detailed in Table 3 and in the distribution section have smooth exocuticles, except on the tail, rather than the finely striated exocuticle as in the type population. It should also be noted that the odontostyle in some of these populations is also longer than in the type specimens. These differences are interpreted herein as interpopulational variation and are not considered by themselves to be of specific significance. (ref. ID; 7209)

Type host and locality

Collected from the rhizosphere of grass at Matador Ranch, Matador, Saskatchewan. (ref. ID; 7209)

Type deposition

Holotype female and allotype male on slide No.278 in the type collection of the Canadian National Collection of Nematodes, Ottawa. 49 female paratypes on slides 278-278W are deposited as followed: 5 paratypes with the United States Department of Agriculture, Beltsville, Maryland; 5 paratypes with the Laboratorio di Nematologia Agraria del C.N.R. Bari, Italy; the remainder deposited in the Canadian National Collection of Nematodes, Ottawa. (ref. ID; 7209)

Measurements

Holotype (female): L=2.24 mm, a=55, b=7.3, c=66, c'=1.3, V=51, odontostyle 78 µm, odontophore 47 µm, distance from oral aperture to guiding ring 65 µm, tail length 31 µm, tail width 25 µm, J=6 µm, J width 11 µm. (ref. ID; 7209)

Allotype (male): L=2.26 mm, a=60, b=7.7, c=68.4, c'=1.3, odontostyle 76 µm, odontophore 53 µm, distance from oral aperture to guiding ring 67 µm, tail length 33 µm, tail width 29 µm, J=4 µm, J width 9 µm, spicules 44 µm. (ref. ID; 7209)

Paratypes (females): N=49; L=2.3(2.1-2.45) mm, a=54(50-58), b=9(6-11), c=70(63-75), c'=1.3(1.2-1.4), V=51(50-52), odontostyle 75(66-82) µm, odontophore 49(46-51) µm, distance from oral aperture to guiding ring 64(56-68) µm, tail length 32(30-36) µm, tail width 26(24-28) µm, J=7(5-11) µm, J width 11(10-14) µm. (ref. ID; 7209)

Xiphinema pacificum Ebsary, Vrain & Graham, 1989 (ref. ID; 6556 original paper)

Differential diagnosis

Xiphinema pacificum n. sp. is most closely related to X. californicum but differs by the larger c' value (1.8-1.9 versus 1.5-1.7), longer odontophore (50-52 versus 47-48 µm), longer tail (37-40 versus 32-33 µm), more posterior vulva (53 versus 50 or 51), and position of caudal papillae (transversely paired versus staggered). (ref. ID; 6556)

Descriptions

Female: Body in an open spiral. Exocuticle smooth, endocuticle with fine transverse striae. Head 11 µm wide, strongly set off from body by a distinct constriction and a transverse incisure. Amphids one-third head width, stirrup shaped. Odontostyle and odontophore robust. Odontophore flanges 6-8 µm wide. Esophageal nuclei obscure. Basal portion of esophagus 60-80 µm long. Intestine lacking any particular features. Cardia conoid rounded. Vulva a simple transverse slit. Vagina about 50% of body width. Genital branches with similar structure and approximate length, each branch occupying 6-9% of total body length. Ovaries reflexed. Prerectum 54-189(103; SD 42) µm long. Prerectum 13-18(15; SD 2.2) µm long. Tail dorsally convex, ventrally almost straight. Terminus conoid rounded. Length of hyaline tail portion (J) 6.5-8.5(8; SD 0.9) µm, J width 8.5 µm. Two transversely paired caudal papillae at midtail. (ref. ID; 6556)

Male: Unknown. (ref. ID; 6556)

Type host and locality

Specimens collected from a sandy soil rhizosphere around the roots of grape at the M. Plut vineyard near the town of Osoyoos, British Columbia, about 3 km north of the Canada-United States border. (ref. ID; 6556)

Type deposition

Holotype female mounted on slide 427 and deposited in the type collection of the CNCN, Ottawa. One hundred and seventeen paratype females are mounted on slides 427a-p and deposited as follows: 12 each with the USDA Nematode Collection, Beltsville, Maryland, and the Laboratoire des vers, Museum National d'Histoire Naturelle, Paris, France, remainder in the CNCN, Ottawa. (ref. ID; 6556)

Measurements

Holotype (female): L=1.9 mm, a=62, b=6.5, c=51, c'=1.8, V=54.5, odontostyle 81 µm, odontophore 52 µm, guiding ring from head apex (GR) 72 µm. (ref. ID; 6556)

Paratype (females): N=20; L=1.8-2.3 mm (1.9; SD 121 µm), a=60-64(62; SD 1.2), b=6.3-7.8(6.8; SD 0.4), c=47-57(51; SD 3.8), c'=1.6-2.2(1.9; SD 0.16), V=52-55(53; SD 1.3), odontostyle 77-92(83; SD 0.9) µm, odontophore 50-54(52; SD 1.2) µm, GR=70-80(76; SD 1.5) µm, tail length 36-49(40; SD 3.2) µm, anal body width 19-23(21; SD 0.06) µm. (ref. ID; 6556)

Additional population:

Pacific Vineyard (females) N=10: L=1.8-2.2 mm (2.0; SD 103 µm), a=53-65(58; SD 2.7), b=5-8.4(7; SD 0.9), c=50-61(54; SD 4), c'=1.5-1.9(1.8; SD 0.13), V=53(52-54), odontostyle 80-88(85; SD 2.29) µm, odontophore 49-52(50.5; SD 1.1) µm, GR=67-77(74; SD 2.7) µm, tail length 33-41(37; SD 2.5) µm, anal body width 20-23(21; SD 1.03) µm. (ref. ID; 6556)

Xiphinema rivesi Dalmasso, 1969 (ref. ID; 6556, 7209)

Descriptions

Female: Body in an open spiral. Head rounded, 10-11 µm wide, slightly set off from body by a very shallow depression. Endocuticle finely striated, exocuticle smooth or finely striated. Odontostyle and odontophore robust, odontophore flanges 6-8 µm. A small 1- to 3-µm mucro may be present in the anterior portion of the esophageal isthmus. Vulva a transverse slit. Vagina occupying about 50% of body width. Ovaries opposed, reflexed. Tail dorsally convex, rounded. (ref. ID; 7209)

Male: None found. (ref. ID; 7209)

Remarks

The very wide destribution of X. rivesi in Ontario is in striking contrast to the rather limited number of occurrence sites of X. americanum. Recently, Forer et al. (1981), Forer and Stouffer (1982), and Wojtowicz et al. (1982) drew attention to the association of X. rivesi with fruit crops infected with tomato ring spot virus (TmRSV) in the eastern United States. Specifically, Forer and Stouffer (1982) emphasized the necessity of reexamining the taxonomy of reputed X. americanum populations because until then X. americanum had been considered the primary vector of this virus. The present taxonomic reexamination indicates that of Niagara Peninsula Xiphinema populations, X. rivesi predominates in the grap growing, TmRSV area near Niagara-on-the-Lake, whereas X. americanum has been positively indentified only from the Fonthill-Welland area, where TmRSV has not been found. Xiphinema americanum has however, been shown to transmit peach rosette mosaic virus to peach at Leamington, Ontario (Allen et al. 1984), while X. rivesi is apparently not vector for this virus. (ref. ID; 7209)