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. ―1― Vol.12 Japanese Journal of Nematology March, 1983 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. ―2― 第12巻日本線虫研究会誌 1983年3月 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 ―3― Vol.12 Japanese Journal of Nematology March, 1983 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 . ―4― 第12巻日本線虫研究会誌 1983年3月 ―5― V∂l.12 Japanese Journal of Nematology 掘azch,1983 A C E F G H - J K L M N D B 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. ―6― 第12巻日本線虫研究会誌 1983年3月 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.

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