Studies on Nematodes Parasitic on Woody Plants2. Genus Xiphinema

第12巻日本線虫研究会誌 1983年3月

Studies on Nematodes Parasitic on Woody Plants 2. Genus Xiphinema CoBB, 1913*

Yukio SHISHIDA**

Five species in the genus Xiphinema, which were found in the Meiji Shrine Forest in Tokyo and at another site, are discussed and figured. They were associeted with various woody plant species. X. incognitum LAMBERTI et BLEVE-ZACHEO,which was originally described from specimens in England obtained from bonsai trees imported from Japan, appears to be native to Japan. Juveniles of X. chambersi THORNE, known so far only from North America, are described and the number of developmental stages of this species was discussed. Additional information on the morphological variability of X. simillimum LooF et YASSIN, known so far only from Africa, X. bakeri WILLIAMS and X. insigne Loos is presented. The intraspecific variation and geographic distribution of these species are discussed. Jpn. J. Nematol. 12: 1-14 (1983)

Among the plant parasitic nematodes found in forests or forest nurseries, Xiphinema species are rather common and frequently encountered20,30,40,58> In his review of relations between Xiphinema and Longidorus and their host plants, CoHN5 noticed that most Xiphinema species have a preference for woody plants. The present paper reports five Xiphinema species associated with woody plants in Meiji Shrine Forest, Tokyo38) and in another site in central Japan.

XIPHINEMA INCOGNITUM LAMBERTI et BLEVE-ZACHEO,1979 (Fig. 1. A-L) Syn. Tylencholaimus americanus in IMAMURA, 1931; KABURAKI& IMAMURA,1933 Xiphinema americanum in MAMIYA, 1969; SOUTHEY, 1973; TOIDA, OHSHIMA & HIRATA, 1978

This species had been treated as X. americanum, a widely distributed species with a great morphological variability. For a detailed description of this species see LAMBERTI & BLEVE- ZACHEO2". Here some additional information on juvenile and female morphology are described and the distribution of this species is discussed. Morphometric data: see Table 1. Juveniles Juveniles appear composed of four groups in odontostyl length, not overlapping each other (Fig. 2 and Table 1), namely J1 (the first stage juvenile), J2, J3 and J4. Four juvenile stages almost equal in tail length. Tail elongate-conoid, slightly convex dorsally in J1, convex dorsally and slightly concave ventrally in J2, as convex dorsally as in J2 in J3 and

* A part of this study was reported at the 23rd annual meeting (1979) of the Japanese Society of Applied Entomology and Zoology. ** Laboratory of Forest Zoology , Faculty of Agriculture, University of Tokyo. Bunkyo-ku, Tokyo 113. Present address: Takada mansion 2-513, Kitamachi 1-16-13, Warabi, Saitama 335, Japan.

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A B C D E F G

H I J K L

Fig. 1. Xiphinema incognitum LAMBERTI et BLEVE-ZACHEO A-B: Female, A: Anterior end, B: "in toto" view, C-G: Tail structure, C: Female, D:J4, E: J3, F: J2, G: J1, H-L: Outlines, H: Female, I: J4, J: J3i K: J2, L: J1.

Fig. 2. Xiphinema incognitum, females and juveniles; Relationship between body length (L) and odontostyl length.

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J4 (and in females). No caudal papilla in any juvenile stages (two pairs on lateral sides in females). Depression between labial region and the rest of the body more conspicuous in J2, J3 and J4 than in J1 (and females).

Host species Podocarpus macrophyllus, Pinus thunbergii, Pinus densiflora, Chamaecyparis pisifera, Juniperus sp., Carpinus tschonoskii, Quercus serrata, Quercus glauca, Quercus salicina, Castanea crenata, Zelkova serrata, Celtis sinensis, Aphananthe aspera, Cercidiphyllum japonicum, Magnolia obovata, Kerria jaPonica, Prunus yedoensis, Daphniphyllum macropodum, Rhus succedanea, Ilex integra, Ilex crenata, Euonymus japonicus, Euonymus sieboldianus, Camellia japonica, Ternstroemia japonica, Cleyera japonica, Eurya japonica, Idesia polycarpa, Fatsia japonica, Aucuba japonica, Cornus controversa, Styrax japonica, Ligustrum japonicum, Callicarpa japonica, and Viburnum awabuki in Meiji Shrine Forest.

Discussion This species was originally described using the specimens obtained in England from the bonsai trees imported from Japan21,39). Measurements and detailed morphology well correspond with SOUTHEY'S deSCripti01139) and that of LAMBERTI & BLEVE-ZACHE021). It is apparant that IMAMURA16),KABURAKI & IMAMURA19),MAMIYA30), TOIDA et al.52), and the present study deal with the same, a single species, because of general correspondence in several cardinal characters such as c' value, tail contour, stylet length and L value (according to TOIDA, Pers. Comm., measurements c'= 1.7 in page 383 in TOIDA et al.52), should be corrected as c'= 1.1 and c'= 1.0 (0.9-1.9)in Table 5 as 1.0(1-1.1)). It appears that LAMBERTI & BLEVE-ZACHE02'),in studying species of so-called X. americanum group, laid stresses on lip region contour, L value, c'value, stylet length and tail contour. The author is of opinion, too, that the Japanese population is a good species, distinctive from those described as X. americanum from other districts of the world3,13,43,45,46,48,49,50,51). LEE & HAN23) reported X. americanum from South Korea. The Korean population has much shorter stylet than the Japanese population does. However, lip region contour, tail contour and c' value (approximately equals 1.1, calculated from the figure) in Fig. 3 of LEE & HAN23) strongly suggest that they are conspecific with the Japanese population. Xiphinema in Figure 28 of HUANG at al.15) reported from various sites of Formosa closely resembles X. incognitum, too, in lip region contour and tail contour, although because of absence of morphometric information, Formosan population cannot be proved. Since X. americanum sensu lato has been proved to be a vector of some plant viruses2,10,17,47), a morphological reexamination of each population of this species complex appears necessary for ascertaining the virus-vector specificity.

XIPHINEMA CHAMBERSI THORNE, 1939 (Fig. 3. A-U) Nec Xiphinema chambersi in GERAERT, 1962; (possibly) TARJAN, 1973

Specimens from Meiji Shrine Forest agree with description by COHN & SHER') and LOOF & YASSIN24) both in measurements and general appearance, except for some slight discrepancies. A description of juveniles and some notes on female morphology follow. Morphometric data: see Table 2.

Juveniles Juveniles appear composed of three groups in L value, stylet length, the distance from the fore end to guiding ring, ABW, and the length of the hyaline portion of the tail. The first stage

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Table 1. Morphometric data on Xiphinema incognitum (specimens from the root-zone of Kerria japonica)

a) Anal body width .

Table 2. Morphometric data on Xiphinema chambersi (specimens from the root-zone of Quercus phillyraeoides)

a) See the text .

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A C E F G H

- J K L M N D

R S T u O P Q

A,B,D-Q50μm

C,R-U500μm

Fig. 3. Xiphinema chambersi THORNE A-C: Female, A: Anterior end, B: Gonad structure, C:"in toto" view, D-E: Juveniles, D: Oesophagus of J3 showing spare odontostyl, E: Anterior end of Ji, F-Q: Tail structure, F-H: Females, I-K: J3, L-N: J2, 0-Q: Ji, R-U: Outlines, R: Female, S: J3, T: J2, U. J.

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juveniles can be distinguished from the rest juveniles by the position of spare odontosty18) ( Fig. 3. E, F ), and it is probable that this species has only four developmental stages, namely J1,J2 J3 and female. Lip region of all the juveniles slightly set off from the body as that of female. The tail of Ji elongate-conoid with a slight ventral curvature terminating in a uniformly conoid hyaline portion. The tail of J2 and J3 almost similar in general appearance, the distal hyaline portion offset, approximately two thirds of the hyaline portion cylindrical; these two stages slightly differ in the ratio of the hyaline portion length to the tail length represented as hyaline % in Table 2. Caudal papilla in visible on J1, none or one pair on J2, one or two pairs on J3. The tail becomes longer as the stage progresses, but the tail length of J3 almost equal to that of female in the range or even slightly greater in the mean than that of female. Host species Quercus phillyraeoides, Quercus serrata, Quercus salicina, Camellia sinensis, and Ligustrum japonicum in Meiji Shrine Forest. Discussion In 1962 Geraert reported this species from Congo11), but it was later referred to X. simillimum LOOF et YAssiN24). Accordingly, X. chambersi has been known only from the United States14,18,24,32,34,35,36,40,48,50).LOOF & YASSIN24)and COHN & SHER') noticed the disagreement in stylet length between the original description and the figure in THORNE48),and this species was redescribed by COHN & SHER6) using six syntype females and a lectotype female. Specimens from Meiji Shrine Forest show slight differences in female characters from the previous descriptions; i.e., the body is shorter (2.2-2.7mm in the previous workse6,24)),the stylet is shorter than COHN & SHER'S (187-198 jim6)) and longer than LOOF & YASSIN'S (152- 1671./m24)), c' value is greater (4.1 in THORNE", calculated from the figure, 3.9-4.7 in LOOF & YASSIN24), 4.3-4.7 in COHN & SHER6)), the tail is longer, the hyaline portion is longer, and hyaline % is greater (calculated from the figures as to the previuos works6,24,48)) TARJAN's specimens from Florida") are characteristic in having conical tails without cylindrical hyaline portions and in smaller c' value (c'= 2.6-5.2). They are very close to one from Maryland treated as unidentified by COHN & SHER (Fig.4. L)6) and may possibly belong to different species. YAGITA"), measuring the stylet length, concluded that Longidorus martini MERNY has only three juvenile stages. DALMASS09) distinguished between J3 and J4 of Xiphinema pyrendicum DALMASSOby their tail shape, because of the presence of an overlap in stylet length. Since the tail shape of all the developmental stages are rather similar in X. chambersi as a general tendency of Xiphinema species with long tails, it is difficult to group decisively juveniles other than J1 into seperate developmental stages. Table 3 shows coefficients of variation of stylet length of X. chambersi specimens studied in the present work. It is shown that the stylet length is very stable in both the second group (represented as J2 in the table) and the third group(JO. Besides, the spare odontostyl length of each group well agrees with that of the next group (Table 2, Fig.4). It is highly probable that X. chambersi grows up to a female through only three moultings, although it can be proved only through a continuous observation on reared juveniles.

XIPHINEMA SIMILLIMUM LOOF et YAssiN, 1971 (Fig. 5. A-F)

Syn. Xiphinema chambersi in GERAERT, 1962 Only one female and one preadult of this species, so far known only from African-24), have been obtained from Meiji Shrine Forest. They agree closely with the original description by LOOF & YASSIN24)in critical characters such as gonad structure and tail shape. An additional

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Fig. 4. Xiphinema chambersi, females and juveniles; Relationship between body length (L) and odontostyl length.

Table 3. Xiphinema chambersi, females and juveniles; Coeffcients of variation of stylet length

information on variability of female morphology and a description of preadult follow . Morphometric data: see Table 4.

Female Body hook-shaped on fixation. Lip region flatly rounded, set off from the body without constriction. Anterior genital branch poorly differentiated; 2.3 as long as the body width at vulva, uterus 47 gm long, oviduct 38 pm long, no sphincter between uterus and oviduct . Posterior genital branch well developed, numerous obcyte in ovary , one intrauterine egg 36 ,um x 211 pm. Tail elongate-conoid, tapering almost uniformly with a ventral curvature , slight dorsal constrictions at proximal end of hyaline portion. Three caudal papillae on each lateral side . Juvenile (preadult) Resemble female in general appearance. Lip region flatly rounded , set off from the body without a distinct constriction. Body gradually tapers posteriorly . Tail shape not similar to that of female; hyaline portion entirely continuous with the rest of the tail , much wider and shorter than that of female, with a globular tip. A pair of caudal papillae on the middle of the tail . A developing gonad at about a quarter of body from fore end, 27 gm long . Discussion Because of scarcity of specimens11,24), a morphological variability of this species is little known. One female examined in the present study differs from those in the previous studies in the following respects; stylet is longer (166-170 pm in LooF & YASSIN24)),vulva is situated more anteriorly ( V=28.6-29.8 in GERAERT11),30-31 in LOOF & YASSIN24)), and hyaline portion is longer (22.3 pm in LooF & YASSIN"), calculated from the figure). Host species Pinus parviflora and Quercus salicina in Meiji Shrine Forest . This species has been found

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Table 4. Morphometric data on Xiphinema simillimum (specimens from the root-zone of Quercus salicina)

from the soil around roots of Citrus sinensis, Rosa sp., Gossypium barbadense and Poinciana regia in Sudan24,55,56),and Musa parasidiaca normalis in Congo11)

X1PHINEMA BAKER1 WILLIAMS, 1961 (Fig. 6. A-1) Host species Celtis sinensis in Meiji Shrine Forest; Fagus crenata and Rhododendron sp. in a natural forest at 1600 m alt., Mt. Akagi, central Japan. Discussion The neck region contour has been regarded as one of cardinal taxonomic characters in Xiphinema species6,21,26,27,29).WILLIAMS53) described the lip region of this species as set off from the body by a constriction. In one female specimen the constriction is very slight (Fig.6. A) and in J3 no constriction observed. Females without constriction were reported also by TARJAN44,46),and LEE & HAN23). Females usually have two pairs of caudal papillae but one female has three papillae on one side and another has only one on one side (Fig. 6. E,F). Variability in the number of caudal papillae has been reported with several Xiphinema species7,9,12,22,28,31,41). Xiphinema bakeri has been known only from North America42,44,46,53),Korea23) and Japan52,57), and is apparently aboriginal to Japan.

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A B C D E

A,B,E,F 50μm

D 500μm

C 100μm

Fig. 5. Xiphinema simillimum LOOF et YASSIN A-D: Female, A: Anterior end, -B: Tail, C: Gonad structure, D:"in toto" view, E-F: Preadult, E: Anterior end, F: Tail.

XIPHINEMA INSIGNE Loos, 1949 Syn. Xiphinema indicum SIDDIQI, 1959 Nec (possibly) Xiphinema insigne in Timm, 1965 Host species Rhus succedanea in Meiji Shrine Forest. Discussion This species has been reported from Egypt33), Israel4), India1), Ceylon25) and Japan37,52), associated with various crops and fruit trees. Japanese populations are characteristic in having longer bodies and greater V value1,37,52). It is considered that some of plant parasitic nematodes distributed through the South Asia to the East Asia have been dispersed artificially with useful plants in the East Asia such as tea (Camellia sinensis), mulberries (Brousonetia papyrifera, Morus alba), varnish trees (Rhus succedanea, R. verniciflua), Taro (Colocasia esculenta), etc.

The author thanks Dr. M. ICHINOHE who kindly commented on the manuscript.

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A B C E F

D G H l

50μm

Fig. 6. Xiphinema bakeri WILLIAMS A-B: Anterior end of female C-D: Juveniles, C: Anterior end of J3, D: Anterior end of J1, E-I: Tail structure, E-F: Female, G: J3, H: J2, I: J.

LITERATURE CITED

1) BAJAJ,H. K. & JAIRAJPURI,M. S.(1977) Variability within Xiphinema insigne populations from India. Nematologica 23, 33-46. 2) BREECE,J. R. & HART, W. H.(1959) A possible association of nematodes with the spread of peach yellow bud mosaic virus. Plant Dis. Rep. 43, 989-990. 3) COBB,N. A.(1913) New nematode genera found inhabiting fresh water and non-brackish soils. J. Wash. Acad. Sci. 3, 432-444. 4) COHN,E.(1969) The occurrence and distribution of species of Xiphinema and Longidorus in Israel. Nematologica 15, 179-192. 5) COHN, E.(1975) Relation between Xiphinema and Longidorus and their host plants. In: Nematode vectors of plant viruses (eds. LAMBERTI,F., et al.), Plenum Press, London & New York, 365-386.

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6) COHN,E. & SHER, S. A. (1972) A contribution to the taxonomy of the genus Xiphinema COBB,1913. J. Nematol. 4, 36-65. 7) COOMANS,A. (1964) Xiphinema basilgoodeyi n. sp. with observations on its larval stages ( Nematoda: Dorylaimida). Nematologica 10, 581-593. 8) COOMANS,A. & DE CONINCK,L. (1963) Observations on spear-formation in Xiphinema. Nematologica 9, 85-96. 9) DALMASSO,A. (1969) Etude anatomique et taxonomique des genres Xiphinema, Longidorus et Paralongidorus ( Nematoda: Dorylaimida). Mem. Mus. Natn. Hist. Nat., Paris, Series A, Zool. 61, 33-82. 10) FULTON, J. P. (1962) Transmission of tobacco ringspot virus by Xiphinema americanum. Phytopathology 52, 375. 11) GERAERT,E. (1962) De Nematodenfauna in en om de wortels van Musa paradisiaca normalis. In: Bijdragen tot de kennis der plantenparasitaire en der vrijlevende nematoden van Kongo. Univ. Gent, pp.1-73. 12) HEYNS,J. (1966) Studies on South African Xiphinema species, with descriptions of two new species displaying sexual dimorphism of the tail ( Nematoda: Dorylaimoidea). Nematologica 12, 369-384. 13) HEYNS, J. (1974) The genus Xiphinema in South Africa 1. X. americanum-group ( Nematoda: Dorylaimida). Phytophylactica 6, 157-164. 14) HOPPER,B. E. (1958) Plant parasitic nematodes in the soils of southern forest nurseries. Plant Dis. Rep. 42, 308-314. 15) HUANG,C. S., TSAI, Y. D., Tu, C. C., LIN, Y. Y. & HUANG,S. P. (1972) Plant parasitic nematodes in Taiwan. Institute of Botany Academia Sinica, Republic of China, Monograph Series No. 1, 61pp. (in Chinese). 16) IMAMURA,S. (1931) Five species of soil nematodes. Jap. J. appl. Zool. 3, 35-38 (in Japanese). 17) IwAKI, M. & KOMURO,Y. (1971) Viruses isolated from narcissus ( Narcissus spp.) in Japan. II. Tomato ringspot virus and its transmission by Xiphinema americanum. Ann. phytopath. Soc. Japan 37, 108-116. (in Japanese). 18) JOHNSON,S. R., FERRIS,V. R. & FERRIS,J. M. (1972) Nematode community structure of forest woodlots. 1. Relationships based on similarity coefficients of nematode species. J. Nematol. 4, 175- 183. 19) KABURAKI,T. & IMAMURA,S. (1933) Soil nematodes of the Nikko District. In: Animals and Plants of the Nikko District, Nikko Toshogu, 516-533 (in Japanese). 20) KIYOHARA,T. (1970) Distribution of plant parasitic nematodes associated with coniferous seedlings in Kyushu, Japan. Bull. Gov. For. Exp. Sta. No. 232, 1-12 (in Japanese). 21) LAMBERTI,F. & BLEVE-ZACHEO,T. (1979) Studies on Xiphinema americanum sensu lato with descriptions of fifteen new species ( Nematoda: Longidoridae). Nematol. medit. 7, 51-106. 22) LAMBERTI,F. & MARTELLI,G. P. (1971) Notes on Xiphinema mediterraneum ( Nematoda: Longidoridae). Nematologica 17, 75-81. 23) LEE, Y. B. & HAN, S. C. (1976) The nematode genus Xiphinema ( Dorylaimida: Longidoridae) from Korea. Kor. J. Pl. Prot. 15, 17-21. 24) LOOF,P. A. A. & YASSIN,A. M. (1970) Three new plant-parasitic nematodes from the Sudan, with notes on Xiphinema basiri SIDDIQI,1959. Nematologica 16, 537-546. 25) Loos, C. A. (1949) Notes on free-living and plant parasitic nematodes from Ceylon. No. 5. J. Zoo. Soc. India 1, 23-29. 26) Luc. M. (1975) Taxonomy of Xiphinema COBB, 1913. In: Nematode vectors of plant viruses (eds. LAMBERTI,F., et al.), Plenum Press, London & New York, 39-52. 27) Luc, M. & DALMASSO,A. (1975) A "Lattice" for the identification of species of Xiphinema COBB, 1913. In: Nematode vectors of plant viruses (eds. LAMBERTI,F. et al.), Plenum Press, London & New York, 53-70. 28) Luc, M., LIMA,M. B., WEISCHER,B. & FLEGG,J. J. M. (1964) Xiphinema vuittenezi n. sp. ( Nematoda: Dorylaimidae). Nematologica 10, 151-163. 29) Luc, M. & TARJAN,A. C. (1963) Note syst-ematique sur le genre Xiphinema COBB,1913 ( Nematoda: Dorylaimidae). Nematologica 9, 111-115. 30) MAMIYA,Y. (1969) Plant parasitic nematodes associated with coniferous seedlings in forest nurseries in eastern Japan. Bull. Gov. For. Exp. Sta. No. 219, 95-119 (in Japanese). 31) MCLEOD,R. W. & KHAIR,G. T. (1971) Xiphinema australiae n. sp., its host range, observations on X. radicicola GooDEY,1936 and X. monohysterum BROWN,1968 and a key to monodelphic Xiphinema

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spp. ( Nematoda: Longidoridae). Nematologica 17, 58-68. 32) NORTON,D. C. & HOFFMANN,J. K. (1974) Distribution of selected plant parasitic nematodes relative to vegetation and edaphic factors. J. Nematol. 6, 81-86. 33) OTEIFA, B. A. & TARJAN,A. C. (1965) Potentially important plant-parasitic nematodes present in established orchards of newly- reclaimed sandy areas of the United Arab Republic. Plant Dis. Rep. 49, 596-597. 34) PERRY,V. G. (1958) Parasitism of two species of dagger nematodes (Xiphinema americanum and X. chambersi) to strawberry. Phytopathology 48, 420-423. 35) RIFFLE,J. W. (1968) Plant parasitic nematodes in marginal Pinus ponderosa stands in central New Mexico. Plant Dis. Rep. 52, 52-55. 36) RUEHLE,J. L. (1968) Plant-parasitic nematodes associated with southern hardwood and coniferous forest trees. Plant Dis. Rep. 52, 837-839. 37) SAIGUSA,T. & YAMAMOTO,Y. (1971) Distribution and hosts of a dagger nematode, Xiphinema insigne Loos, detected on export lily bulbs. Res. Bull. Pl. Prot. Serv. Japan 9, 27-38 (in Japanese). 38) SHISHIDA,Y. (1979) Studies on nematodes parasitic on woody plants. 1. Family Trichodoridae (Thorne, 1935) CLARK,1961. Jpn. J. Nematol. 9, 28-44. 39) SOUTHEY,J. F. (1973) Identification of Xiphinemo species. In: The Longidoridae, Manual Worksh. Nemat. Group Assoc. appl. Biologists, 37-58. 40) SPRINGER.J. K. (1964) Nematodes associated with plants in cultivated woody plant nurseries and uncultivated woodland areas in New Jersey. New Jersey Dep. Agr. Circ. 429, 4Opp. 41) STURHAN,D. (1978) Zwei neue Xiphinema-Arten aus Deutschland ( Nematoda, Dorylaimida). Nematologica 24, 19-28. 42) SUTHERLAND,J. R., DUNN,T. G. & COUSENS,N. B. F. (1970) Morphometric and morphological characteristics for identifying the life stages of Xiphinema bakeri WILLIAMS,1961 (Nematoda: Longidorinae). Can. J. Zool. 48, 771-773. 43) TARJAN, A C. (1956) Known and suspected plant-parasitic nematodes of Rhode Island. II. Xiphinema americanum with notes on Tylencholaimus brevicaudatus n. comb. Proc. helminthol. Soc. Wash. 23, 88-92. 44) TARJAN, A. C. (1964) Two new American dagger nematodes (Xiphinema: Dorylaimidae) associated with citrus, with comments on the variability of X. bakeri WILLIAMS,1961. Proc. helminthol. Soc. Wash. 31, 65-76. 45) TARJAN, A. C. (1969) Variation within the Xiphinema americanum group ( Nematoda: Longidoridae). Nematologica 15, 241-252. 46) TARJAN,A. C.(1974) The dagger nematodes (Xiphinema COBB) of Florida. Proc. Soil Crop Sci. Soc. Fla. 33, 92-95. 47) TAYLOR,C. E. &ROBERTSON, W. M. (1975) Aquisition, retension and transmission of virus by nematodes. In: Nematode vectors of plant viruses (eds. LAMBERTI,F. et al.), Plenum Press, London & New York, 253-275. 48) THORNE,G.(1939) A monograph of the nematodes of the superfamily Dorylaimoidea. Capita zool. 8,1-261. 49) THORNE,G.(1961) Principles of Nematology. McGraw-Hill, Inc., New York, 553pp. 50) THORNE,G.(1974) Nemotodes of the Northern Great Plains. Part II. Dorylaimoidea in part (Nemata: Adenophorea). Agr. Exp. Sta., South Dakota State Univ., Tech. Bull. 41, 120pp. 51) TIMM, R. W. (1965) A preliminary survey of the plant parasitic nematodes of Thailand and the Phillipines, Bankok, SEATO Secretal. Gen. 71pp. 52) TOIDA,Y., OHSHIMA,Y. & HIRATA,A. (1978) The nematode species associated with mulberry trees and their morpho- and ecological characteristics. Bull. Sericul. Exp. Sta. 27, 369-396 (in Japanese). 53) WILLIAMS, T. D. (1961) Xiphinema bakeri n. sp. ( Nematoda: Longidorinae) from the Fraser River Valley, British Columbia, Canada. Can. J. Zool. 39, 407-412. 54) YAGITA, H. (1975) The life history and biology of the needle nematode, Longidorus martini Merny. I. Jpn. J. Nematol. 5, 10-15 (in Japanese). 55) YASSIN, A. M. (1974) A note on Longidorus and Xiphinema species from the Sudan. Nematol. medit. 2, 141-147. 56) YASSIN, A. M., LOOF, P. A. A. & OOSTENBRINK,M. (1970) Plant parasitic nematodes in the Sudan. Nematologica 16 567-571. 57) YOKOO, T. (1970) Soil nematological notes. II. Agric. Bull. Saga Univ. 29, 15-28 (in Japanese).

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58) ZINNO, Y. & IGARASHI,Y.(1972) Distribution of plant parasitic nematodes associated with coniferous seedlings in Shikoku, Japan. Bull. Gov. For. Exp. Sta. No.246, 11-20 (in Japanese). Accepted for publication: July 22, 1982.

和文摘要

樹木に寄生する線虫類の分類学的研究 2.Xiphinema属

宍田幸男

明治神宮境内林の樹木根辺土壌より得られた、Xiphinema5種の形態に関する知見を報告する。X. incognitum LAMBERTI et BLEVE- ZACHEO, 1979は、日本からイギリスへ持ち込まれた盆栽の樹木数種の根辺より分離された標本を基に原記載されたが,これまで日本よりX.iphinema COBB,1913 として報告されていたものと,計測値・形態的特徴ともによく一致する。本種は世界各地よりX

ameracanum として記載・報告された集団からは明らかに形態的に区別され,本種を独立種とした

LAMBERTI & BLEvE-ZAcHEoの措置は妥当であると考えられる。X.chambersi THoRNE ,1939は,これまで北アメリカのみから知られていたが,幼虫期の形態が初めて記載された。その形態計測値と尾部の形態とから,本種は幼虫期を3つしか持たないことが強く示唆される。X.simillimum LOOF et YASSIN,1971はこれまでコンゴ,スーダソのみから少数個体しか知られていない。最終期幼虫が初めて記載されたが,これまで検出例・検出個体数ともに少ないため,本種の種内変異に関する知見は乏

しい。X.bakeri WILLIAMs,1961は,これまで北アメリカ・朝鮮・日本のみから知られるが ,群馬県赤城山天然林数箇所からも検出され,日本に土着の種と見られる。本種は原記載において,雌が2対

の尾乳頭をもつことがX.index THoRNE et ALLEN,1950との識別点の1つとされたが、尾乳頭の数には変異が認められた。X.insigne Loos,1949は,中近東から南アジアを通り東アジアまで分布する種であると考えられるが、日本の集団は,極めて大きな体長・V値をもつことが特徴的である。

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