Dolichodorus grandaspicatus n. sp.: Robbins 511 scription and SEM observations of Dolichodorus 10:28-34. marylandicus n. sp. with a key to species of 4. Sher, S. A., and A. H. Bell. 1975. Scanning Dolichodorus. J. Nematol. 13:128-135. electron micrographs of the anterior region of 3. Robbins, R. T. 1978. Descriptions of females some species of Tylenchoidea (Tylenchida: Nema- (emended), a male, and juveniles of Paralongidorus toda). J. Nematol. 7:69-83. microlaimus (Nematoda: Longidoridae) J. Nematol. Morphological Comparisons Between Xiphinema rivesi Dalmasso and X. americanum Cobb Populations from the Eastern United States' .X'|AREK 1"~. ~¥OJTOWICZ'-', A. MORGAN GOLDEN :~, L. B. FORER 4, AND R. F. STOUFFER r' Ab.~tract: Tltough in the past Xiphinema americanum has been the most commonly reported dagger nematode in the eastern United States, our studies revealed the presence in l'ennsvlvania of a previously tntrecognized and unreported species related to X. americanum, Morphometric data atul photomicrographs establish the identity of this form as X. rivesi and show expected variations in populations of this species from various locations. Similar data and illustrations are given for X. americam~m populations from Pennsylvania and other areas, showing variations attd relationships. Xiphinema rivesi is widely distributed in the fruit producing area of south- cctttral l'cttnsylvania atttl is also reported herein from raspherry in Vermont and apple in Maryland attd New York. This species is frequently found it, fruit growing areas of Pennsylvania associated with lomatn r'ngspot virus-induced diseases and is also found associated with corn, bluegrass sod, and alfalfa. Key words: Xiphinema amerieanum, X. rivesi, morphology, occurrence, fruit orchards, virus transmission. Journal of Nematology 14(4):511-516. 1982. A previously unrecognized, didelphic vestigated. Preliminary results indicate that species of the nematode genus Xiphinema this previously unidentified species of Xi- Cobb, 1913 was isolated by the senior phinema is able to transmit TmRSV (3), attthor in 1977 from soil in a southcentral and its presence in fruit orchards, alone or Pennsylvania (Adams County) apple or- in species mixtures, has complicated dagger chard. Since the initial isolation, the spe- nematode identifications, especially in virus cies has been isolated frequently from peach transmission research. This report primarily and apple orchards, grape vineyards, and provides morphological data and details of soft fruit plantings as well as alfalfa, corn, the newly isolated Xiphinema species iden- and bluegrass in this particular area of tified herein and the related and commonly Pennsylvania and from fruit growing areas occurring species, X. americanum Cobb, in nearby states. Many of the sites where 1913. this nematode has been found have a his- tory of tomato ringspot virus (TmRSV) MATERIALS AND METHODS problelns in the fruit crops. The possible association between this species of Xiphi- Soil samples were taken with an Oak- nema and TmRSV disorders is being in- field soil probe to a depth of approximately 23-30 cm, depending on soil condition and Received for publication 16 March 1982. texture. Multiple probes were combined to ~This research was funded in part by Agricultural Re- give a composite sample of approximately search Project Contract :~614498 trom the Pennsylvania l)epartmeot of Agriculture, Bureau of Plant Industry. 550 cm ~. Each composite sample was eVisiting Scientist, Pennsylvania State University, Fruit Research Laboratory, Biglerville, PA 17307. Present address: thoroughly but gently mixed, a 100-cm3 Research Institute of Pomo[ogy and Floriculture, 96-100 subsample was taken, and the nematodes Skierniewice, Poland. '~Nematologist, Nematology Laboratory, U.S. Department extracted by a modification of the decant- of Agriculture, ARS, BARC-West, Beltsville, MD 20705, ing and sieving technique described by 4Nematologist, Pennsylvania Department of Agriotltnre, Bureau of Plant Industry, Harrisburg. PA 17110. Flegg (2). The extracted nematodes were ~l'rofessor, Department of Plant Pathology, Pennsylvania killed with a 3.4% hot formaldehyde solu- State University. Fruit Research Laboratory, Biglerville, PA 17307. tion, fixed in formalin/acetic acid fixative, & Table 1. Morphometric data of Xiphinema rivesi populations from the United Stales (5) and France (1). Populations (origin and host) Victoria Eureka, Springs, Bordeaux, Kansas, USA Nebraska France Walnut et al. Cottonwood Grape (types) Hyde Park, (after (after (after Adams Co., Pennsylvania, USA Vermont, USA Lamberti Lamberti Dahnasso, Characteristics ( 2 9 ) Peach Apple Rubus sp. et al., 1979) et al., 1979) 1969) L (ram) 1.8 (1.7-2.0) 1.8 (1.7-1.9) 2.1 (1.9-2.2) 1.7 (1.6-1.9) 1.9 (1.9-2) 1.96 (1.68-2.1) a 50 (48-53) 47 (42-54) 40 (3942) 41 (374-44) 45 (41-50) 41.8 (37--49) b 6.4 (5.8-7.1) 6.7 (5.9-7.4) 7.1 (6.1-7.8) 6.4 (6.1-6.9) 6.6 (6.5-6.9) 6.28 (5.7-6.9) e 56 (50-61) 56 (52-62) 64 (62-70) 51 (48-57) 59 (58-61) 55.5 (51-59) v% 52 (50-53) 53 (51-54) 52 (51-53) 52 (56-53) 52 52.2 (51-54) Total stylet length (#m) 140 (135-143) 145 (139-151) 149 (144-154) 135 (128-147) 133 (127-140) 147 (140-151) Odontostyle (#m) 90 (86-92) 92 (85-97) 94 (90-98) 84 (80-92) 85 (83-90) 96 (90-i01) Odon tophore (#m) 50 (48-51) 52 (49-55) 56 (51-62) 51 (48-55) 48 (44-50) 51 (48-57) Guide ring from oral aperature (#m) 68 (65-71) 75 (74-78) 79 (62-88) 74 (70-78) 74 (73-77) 76 (71-79) Tail (/zm) 33 (31-34) 32 (30-34) 32 (30-34) 34 (32-36) 33 35 (30--40) J (#m) 7.6 (6.9-8.2) 6 (4.3-8.2) 7.2 (5.6-8.6) 7 (6-8) 6.5 (6-7.5) o°, Body diameter at anus (#m) 24 (22-25) 24 (19-28) 30 (28-31) 25 (22-26) 24 (23-25) 26 (23-29) Body diameter at beginning of J (#m) 10 (9-11) 11 (7.7-14) 14 (13-16) 11 (9.5-11.5) 12 (11-14) Xiphinerna Morphology, Identity, Occurrence: Wojtowicz et al. 513 and transferred to glycerol by the glycerol- Males rare, hody similar to that of fe- ethanol procedure of Seinhorst (7). Speci- male, with greater curvature in posterior mens for comparison were collected from part of body. Distance from anterior part other locations and other hosts as indicated ot the body to the guide ring, 76 ~tm. Tail in Tables 1 anti 2; in some cases, prepared slightly more slender than in female, c' = specimens were obtained from colleagues. 1.3. Spicules 49 ~tm long. An adanal pair of Common procedures were used in taking supplenlents present with six supplements. measurements and photomicrographs. These details and data indicate that this Xiphinema from Pennsylvania and certain RESULTS other areas is X. rivesi. Morphometric data are given in Tahle In Table 2 morphometric data on four 1 for two Xiphinema populations from potmlations of X. americanum are pre- Pennsylvania and one from Vermont; also sented to facilitate identification anti to for X. rivesi Dalmasso, 1969 (1) from Kan- show relationship and variations of this sas and Nebraska (after Lamberti et al. species. The data consist of our measure- [6]) and from France (from original de- ments of two populations, one each from scription by Dalmasso [1]). The data on the Pennsylvania and New York, and details Pennsylvania and Vermont populations are from Lamherti et al. (6) on a Maryland particularly close to that for X. rivesi, population and the type population from especially the population from France. Rhode Island. These populations are es- Specifically, the stylet length, vulva per- sentially the same, although the styler of centage, and various tail measurements of the Maryland populations is a bit longer these populations are well within the range than the others. Photomicrographs (Figs. of variation expected of X. rivesi from 22-39) show the characteristics of head and diverse hosts, areas, and countries. The tail areas of females of populations of X. photomicrographs of head and tail areas americanum on different hosts from Penn- (Figs. 1-20) of populations from different sylvania, New York, and Maryland. Un- hosts and localities provide additional in- like X. rivesi, the head of X. americanum formation on this species. is slightly offset, its stylet is shorter, and its A brief description and further details tail is of a different shape, being especially of the population from peach (Adams more pointed. These characteristics in par- County, Pennsylvania) follows: Body taper- ticular are very useful in separating X. ing gradually, forming a closed "C." Lip americanum from X. rivesi. region rounded, continuous with the rest of the body, 10 ~m wide. Amphids stirrup- DISCUSSION shaped. Amphid aperature slit-like, about 1/2 as wide as lip region; odontostyle ro- In the past the dagger nematode com- bust, 90 ~tm long, with flanged odontophore monly reported from the eastern United 50 /ml long. Guiding sheath 3-4 ~m long States was identified as X. arnericanum. with a double guiding ring. Basal ring For example, the population of X. rivesi situated 69 /~m from the anterior extremity from Vernlont, which was reexamined of the specimen. The basal bulb of oeso- recently and is discussed here, was initially phagus occupies about 1/4 of the total identified and reported in 1965 as X. amer- oesophageal length anti measures 75-85 ~tm icanum (5); however, another population long and 16-25 ~m wide. Nuclei difficult to of Xiphinema, recently found, was isolated see. Cardia bluntly conical, nearly as long repeatedly and was recognized to differ as wide.