Identification of Meloidogyne Species on the Basis of Head Shape and Stylet Morphology of the Male 1 J

Aleutian Heteroderoidea: Bernard 513 cultures were increased in a growth cham- 5. Seinhorst, J. W. 1959. A rapid method for ber at 15 C. No galling was observed on the transfer of nematodes from fixative to anhy- drous glycerin. Nematologica 4:67-69. oat, rescue, or tomato, but these cultures 6. Taylor, A. L., and J. N. Sasser. 1978. Biology, were kept in the greenhouse and thus may identification and control of root-knot nematodes have been grown at unsuitable tempera- (Meloidogyne species). North Carolina State Uni- tures. versity, U.S.A,I.D. 7. Triantaphyllou, A. C. 1979. Cytogenetics of root-knot nematodes. Pp. 85-109 in F. Lamberti LITERATURE CITED and C. E. Taylor, eds. Root-knot nematodes (Mcloidogyne species). Systematics, biology and I. Eroshenko, A. S. 1978. (A new species of control. New York: Academic Press, Meloidodera [Nematoda, Heteroderidae] from the 8. Whitehead, A. G. 1968. Taxonomy of Primorsk territory.) Parazitologiya 12:456-459 (In Meloidogyne (Nematodea: Heteroderidae) with de- Russian). scriptions of four new species. Trans. Zool. Soc. 2. Jenkins, W, R. 1964. A rapid centrifugal- Loud. 31:263-401. flotation technique for separating nematodes from 9. Wouts, W. M. 1973. A revision of the family soil. Plant Dis. Rep. 48:692. Heteroderidae (Nematoda: Tylenchoidea). II. The 3. Mulvey, R. H., and R. V. Anderson. 1980. subfamily Meloidoderinae. Nematologica 19:218- Description and relationships of a new root-knot 235. nematode, Meloidogyne sewelli n. sp. (Nematoda: 10. Young, L. D. 1975. A Meloidogyne sp. on Meloidogynidae) from Canada and a new host American beachgrass in North Carolina. Unpub- record for the genus. Can, J. Zool. 58-1551-1556. lished M.S. thesis. North Carolina State University. 4. Robbins, R. T. 1978. A new Ataloderinae 11. Young, L. D., and L. T. Lucas. 1977. Hosts (Nematoda: Heteroderidae), Thecavermiculatus of Meloidogyne sp. on American beachgrass. Plant gracililancea n. gen., n. sp. J. Nematol. 10:250-254. Dis. Rep. 61:776-777.

Identification of Meloidogyne Species on the Basis of Head Shape and Stylet Morphology of the Male 1 J. D. Eisenback and Hedwig Hirschmann x Abstract: Head shape and stylet morphology of males of 90 populations of M. arenaria, M. hapla, M. incognita, and M. javanica from geographic regions of the world were compared by light microscopy (LM). In addition, stylets of one population each of M. arenaria, M. incognita, and M. javanica and three different chromosomal forms of M. hapla race A and two of race B were excised and examitted with a scanning electron microscope (SEM). Differences among species occurred in both head and stylet morphology. Head morphology differed in size and shape of the head cap, annulation of the head region, and width of the head region relative to the first body annule. Differences in stylets occurred in size and shape of the cone, shaft, and knobs. All populations of M. hapla, except one, had similar head morphology, but stylet morphology was different between cytological races A and B. Populations of M. javanica varied with respect to the presence of head annulations. Head shape and stylet morphology of males are recommended as additional characters useful in the identification of root-knot nematodes. Key words: Meloidogyne arenaria, M. hapla, M. incognita, M. ]avanica, root-knot nematodes, cytological races, intersexes, scanning electron microscopy, taxonomy.

Identification of the four common spe- arenaria (Neal) Chitwood, M. incognito cies of root-knot nematodes--Meloidogyne (Kofoid and White) Chitwood, M. ]avanica (Treub) Chitwood, and M. hapla Chitwood Received for publication l0 February 1981. 1Paper No. 6785 of the Journal Series of the North --is often difficult and time consuming. Carolina Agricultural Research Service, Raleigh. North Caro- Various approaches to Meloidogyne tax- lina. This study was supported, in part, by National Sci- ence Foundation Grant DEB-7917386 to A. C. Triantaphyllou onomy include host response (12,14,17), and U.S. Agency for International Development Contract cytology (17,18,19), biochemistry (3,4,11), to-C-t234 to J. N. Sasser. "-Research Associate and Professor, respectively, Depart- and morphology (1,2,5,6,7,8,9,12,13,15,20, ment of Plant Pathology, North Carolina State University, 21,22). Host-response tests require adequate Raleigh, NC 27650. We thank Dr. J. N. Sasser, Department of Plant Pathology, North Carolina State University. for amounts of nematode inoculum, and the conducting host differential tests and Dr. A. C. Tri- results may not be known for several weeks. antaphyllou, Department of Genetics, North Carolina State University, for providing cytological information. Cytological and biochemical studies require 514 Journal o] Nematology, Volume 13, No. 4, October 1981 specific techniques and sophisticated equip- the respective species (14,16), and the pop- ment. Identification based on morphology ulations o1: M. hapla represented the two can be rapid and practical if reliable dif- cytological races (18). ferentiating characters can be determined. Males were obtained by incubating Generally, Meloidogyne species are identi- washed infected root systems in a moist fied by the perineal pattern morphology of chamber at room temperature. The males the adult female (9,10,16). In populations were killed with hot TAF and mounted in of the four common species, however, the fixative for LM observations. Some perineal patterns are variable and definite specimens were killed, fixed, and mounted identification is not always possible (5,9,10, in glutaraldehyde (7) for additional mor- 12,13). Additional characters that are less phological studies, and others were ex- variable are needed to supplement perineal amined alive for comparison with fixed ma- pattern morphology. terial. For diagnostic studies the males must In a recent scanning electron microscope be viewed in exact lateral position. Camera (SEM) study, we reported that the head lucida drawings and LM photographs of morphology of males of M. arenaria, M. the anterior body region including the incognita, M. javanica, and M. hapla was stylet were made of representative popula- distinct for each species (7). Observed dif- tions. At least 30 specimens from each pop- ferences among species, and in M. hapIa ulation were examined. Eight of the popu- between races, were striking. Subsequent lations used in this study were the same studies revealed that some of these differ- populations used in previous LM and SEM ences, especially in head shape, could also observations of second-stage juveniles, be detected in the light microscope (LM). males, and females (6,7,8). When examining root-knot nematode fe- Stylets of males of one population each males (8), we shouted that differences occur of M. arenaria, M. incognita, and M. javan- in stylet morphology among the four com- ica and five different chromosomal popula- mon species. tions of M. hapla were observed by SEM. The present study compares by LM the The following populations were examined: head shape of males of several populations M. arenaria, 351-Fla; M. incognita, 68-NC; of each of the four common species of root- M. iavanica, 76-GA; M. hapla race A, 6-NC, knot nematodes. It also compares by LM 42-Can, and 86-NC; and M. hapla race B, and SEM the morphology of stylets of males 48-NC and 230-Chile. The technique orig- of one population each of M. arenaria, M. inally developed for the removal of stylets incognita, and M. javanica and five differ- of females (8) was adapted to males. Five ent chromosomal populations of M. hapla. males were transferred into a drop of 45% lactic acid on a glass coverslip. The specimens were cut behind the median bulb with MATERIALS AND METHODS a dental root canal file and processed for Ninety populations of the four common SEM observations as previously described root-knot nematode species from geographic (8). At least g0 stylets from each population regions of the world were selected from the were observed. The LM observations of the Meloidogyne collection at North Carolina stylet morphology of all populations were State University. Thirteen populations compared with the SEM observations of the were M. arenaria; 12, M. hapla; 44, M. in- eight populations previously listed. cognita; and 31, M. favanica. All populations were propagated on tomato (Ly- copersicon esculentum Mill. 'Rutgers') in a OBSERVATIONS greenhouse maintained at 22-28 C. Each Head morphology: The basic head mor- population had been characterized by its phology of Meloidogyne males is derived ability to reproduce on five host differ- from SEM and LM observations (Figs. 1, entials (16), and many populations had 2). Labial disc and medial lips as observed been identified on a cytological basis. The in the SEM (7) appear in the LM as a populations of M. arenaria and M. in- single structure, the "head cap." The an- cognita belonged to several host races of nulations in the head region, so distinct in Meloidogyne Male Head Shapes: Eisenback, Hirschmann 515 and the lateral field begins near the level of ba.....__L1 the stylet knobs. The four common species differ in their head morphology with respect to shape and s[[ff( size of the head cap, presence or absence of annttlation in the head region, and the way the head region fuses with the body region. In M. arenaria (Figs. 3, 9) the head cap is low, slopes posteriorly, and is nearly as wide as the head region. Usually the head region 2 is marked by 1-2 incomplete annulations and is not set off from the body region. M. incognita males (Figs. 4, 10) possess a high head cap formed by a large round labial V disc that is raised above the medial lips b! and centrally concave. The head cap is as c wide as tile head region. The head region generally bears 2-4 incomplete annulations, s~ although some populations may have com- sl plete annulations. The head region is not set off. In M. javanica (Figs. 5, 11) the head cap is high and rounded and almost as wide as the head region. The head region is not set off and is usually smooth, although 5 of the 31 populations had 2-3 incomplete annules. The head shapes of males of all populations of M. hapIa race A (Figs. 6, 12) and race B (Figs. 7, 13) are similar except for one population. In M. hapla the head cap is high and much narrower than the head region which lacks annulations and is distinctly set off from tbe body. Generally, the distance between body annulations, as well as their diameter, decreases as they near the head region. Males of population Figs. 1-2. Diagram illustrating the generalized 42-Can of M. hapla (Figs. 8, 14) are unique head morphology of a male of the genus Mel- because the head cap is comparatively wider oidogyne. 1) Face view (derived from SEM) and 2) lateral view (derived from LM and SEM); ba, body than in typical M. hapla populations and annule; bc, body cavity; bp, basal plate; cf, cephalic the head region is not set off from the body. framework; cs, cephalic sensiltum; c, cuticle; dgo, Body annulations are indistinct. dorsal gland orifice; e, esophagus; ha, head annula- Styler morphology: The excised stylet tion; hc, head cap; hr, head region; ils, inner labial sensillum; ld, labial disc; If, lateral field; 11, lateral and attached cuticular lining of the esoph- lip; ml, medial lip; ps, prestoma; sin, somatic agus of tile male as seen in the SEM (Fig. muscles; s, stoma; sc, stylet cone; sk, stylet knobs; 15) is similar to that of the female (8) ex- sl, stylet lumen; sp, stylet protractor muscles; ss, cept for a few structural differences. In the styler shaft; v, vestibule; re, vestibule extension, male the opening of the stylet lumen is the SEM, are more difficult to observe in located one-fourth the length of the cone tile LM. Generally, the head region is in from the stylet tip, the esophageal lumen is the same contour with the anterior body smaller in diameter, and the triradiate lin- region, but in some specimens the diameter ing of the smaller metacorpus pump is of of the head region is larger than that of the tile same thickness throughout. first body annule and thus the head region Differences in stylet morphology of the appears distinctly set off. The anterior body male as seen in LM and SEM occur in the region bears annules in regular iaterva!s, shape of the cone, shaft, and knobs. In M. 516 Journal of Nernatology, Volume 13, No. 4, October 1981

Figs. 3-8. LM photographs of lateral view of males. 3) Meloidogyne arenaria. 4) M. incognita. 5) M. iavanica. 6) M. hapla race A. 7) M. hapla race B. 8) M. hapla race .k population 42-Can. All figures are same scale as gig. 8.

arenaria (Figs. 3, 9, 16) the styler tip is tion with the knobs which are broadly pointed and there may be a slight projec- elongate to round, sometimes anteriorly in- tion on the ventral side of the cone, pos- dented, and set off from the shaft. In M. terior to the orifice. The anterior two-thirds javanica (Figs. 5, 11, 18) the anterior two- of the cone gradually increase in width and thirds of tlle cone gradually increase in the posterior one-third greatly increases in width. Styler lumen openings were found width. The shaft can be wider in the mid- in only 7 of 30 specimens. The shaft is dle, but generally remains cylindrical. The cylindrical and the styler knobs are low rounded, robust knobs gradually merge and wide, often anteriorly indented, and with the shaft. The stylet tip of M. incog- set off from the shaft. The styler morphol- nita (Figs. 4, 10, 17) is blunt and the an- ogy of tile M. hapla populations is unique terior portion of the cone is blade-like. for tile species but the two races have Often there is a pronounced projection slightly different stylets. In populations of posterior to the stylet opening. The cylin- both races the stylet cone gradually in- drical shaft may narrow slightly at the junc- creases in width, and the base of the cone is Meloidogyne Male Head Shapes: Eisenback, Hirschmann 517

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Figs. 9-14. Line drawings of lateral view of males. 9) Meloidogyne arenaria. 10) M. incognita. 11) M. iavanica. 12) M. hapla race A. 13) M. hapla race B. 1t) M. hapla race A population 42-Can. All figures are same scale as Fig. 14. only slightly wider than the anterior por- of many populations from various sources tion of the shaft. In populations of race A around the world shows that head shape (Figs. 6, 8, 12, 14, 19) the shaft is wider near and stylet morphology are good, reasonably its junction with the knobs than at the reliable taxonomic characters for the identi- junction with the cone, whereas in race B fication of the four common root-knot populations (Figs. 7, 13, 20) the shaft re- nematode species by light microscopy. We mains cylindrical except for a slight nar- also illustrated the value of the SEM in rowing near its junction with the knobs. recognizing morphological details in the The rounded, set-off stylet knobs are larger LM that might otherwise be missed. in race B populations. The stylets of M. The populations of M. arenaria be- hapla are smaller than those of the other longed to cytological race A and repre- three common root-knot nematode species. sented host races 1 and 2 (16). Although minor morphological differences were DISCUSSION noticed among populations, certain basic The present study of Meloidogyne males characteristics are common for this species. 518 Journal of Nematology, Volume 13, No. 4, October 1981 In some specimens of M. arenaria the head 15 morphology may be similar to that of M. iavanica males, particularly if the /lead cap is high or does not slope much posteriorly. However, the two species can easily be sep- arated by stylet morphology. In M. javanica the stylet knobs are low, wide, and set off from tile shaft,, whereas in M. arenaria the knobs are rounded and gradually merge with tile shaft. The populations of M. incognita belonged to host races 1, 3, and 4 (16) and included only cytological race A. All populations had similar head shape and stylet morphology. The styler morphology of M. incognita resembles that of M. javanica in tile LM because the uniquely shaped stylet cone of M. incognita cannot always be seen clearly; also, in some specimens the stylet /7 knobs appear as wide as in M. javanica. These two species, however, can easily be distinguished on the basis of head morphology. / Presently, only one cytological and one host race of M. javanica are recognized. The head shape of all populations in this study /i ti was similar. Most populations did not have head annulations, although 4 of tlle 26 populations examined had 2-3 head annulations. Chitwood, in his original description of M. javanica, described males with three head annulations (2). Future investi- gations should attempt to correlate head / annulation with other taxonomic characters. Fourteen populations of M. javanica had male intersexes in large proportions, whereas the remaining populations did not produce intersexes, even though many males were present. Chitwood (2) stated that true males were rare, and Triantaphyl- lou (17) has reported on intersex formation in this species. Further research should elucidate if all populations of M. javanica have the ability to produce male intersexes. Populations of M. hapla included [our each from cytological race A and B (18). The populations of the two cytological

~o.o pm races were similar in head shape, except for population 42 from Canada with 15 chro- mosomes. Stylet morphology of the races, Fig. 15. SEM photograph of an excised stylet and however, is quite different, and individual attached cuticular lumen lining of the esophagus of a Meloidogyne male. populations can be identified according to stylet length and shape o[ stylet shaft. In his original description of M. hapla, Chit- 16 17 18 19 20 f

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,°

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g~ Figs. 16-20. SEM photographs of excised stylets. 16) Meloidogyne arenaria. 17) M, incognita. 18) M. javanica. 19) M. hapla race A. 20) M. hapla race B. All figures are same scale as Fig. 20. G-x 520 Journal of Nematology, Volume 13, No. 4, October 1981 wood (2) pointed out two varieties based useful supplemental taxonomic characters. on differences in male stylet length. In Our observations of male head shape and one group the males had short stylets (17- stylet morphology of these four species 18 /zm), in the other long stylets (20 /tm). further emphasize the importance of male According to our findings, populations with head shapes and stylet morphology in the short stylets belong to race A, populations identification of the four common species with long stylets to race B. of root-knot nematodes. Our findings con- A comparison of the stylet and attached firm some of Chitwood's (2) earlier findings cuticular lumen lining of the female (8) as illustrated in his figures IA (M. arenaria), with that of the male reveals some struc- 5A,K (M. incognita), 2E (M. javanica), and tural differences. In the female the esopha- 3C,V,X,Z (M. hapla). geal lumen lining of the procorpus is thick and the triradiate lining of the metacorpus LITERATURE CITED pump is large and thick. The thick, rigid 1. Allen, M. W. 1952. Observations on the genus edges of the lining support the metacorpus Meloidogyne Goeldi, 1887. Proc. Helrninthol. Soc. pump, and the thin, flexible inner portions Wash. 19:44-51. are pulled apart by the pump muscles, thus 2. Chitwood, B. G. 1949. Root-knot nematodes producing the suction required for feeding. I. A revision of the genus Meloidogyne Goeldi, 1887. Proc. Helminthol. Soc. Wash. 16:90-104. In the male the triradiate lining is thin 3. Dahnasso, A., and J. B. Berg& 1978. Molecular throughout and the pump probably is not polymorphism and phylogenetic relationship in functional. Styler orifices were not seen in some Meloidogyne spp.: Application to the taxon- 70% of the M. javanica males which further omy of Mcloidogyne. J. Nematol. 10:323-332. 4. Dickson, D. W., D. Huisingh, and J. N. Sasser. indicates that males do not feed. The open- 1971. Dehydrogenases, acid and alkaline phos- ing of the stylet lumen in the male is lo- phatases, and esterases for chemotaxonomy of se- cated more posteriad on the cone than in lected Meloidogyne, Ditylenchus, Heterodera and the female. Aphelenchus spp. J. Nematol. 3:1-16. When stylets of the two sexes are com- 5. Dropkin, V. H. 1953. Studies on the variability of anal plate patterns in pure lines of Mel- pared within the same species (8) similar oidogyne spp., the root-knot nematode. Proc. morphological trends are apparent. In M. Helminthol. Soc. Wash. 20:32-39. arenaria the styler is robust and the knobs 6. Eisenback, J. D., and H. Hirschmann. 1979. gradually merge with the stylet shaft in the Morphological comparison of second-stage juveniles of six populations of Meloidogyne hapla by SEM. male and female. In M. incognita the stylet J. Nematol. 11:5-16. cone is uniquely shaped in both sexes and 7. Eisenback, J. D., and H. Hirschmann. 1980. the overall shape of the knobs is similar, Morphological comparison of Meloidogyne males even though the female stylet knobs are by scanning electron microscopy. J. Nematol. 12: 23-32. wider. In M. iavanica the stylet cone is 8. Eisenback, J. D., H. Hirschmann, and A. C. straight and the knobs are short and wide Triantaphyllou. 1980. Morphological comparison and anteriorly indented in both sexes. by LM and SEM of Meloidogyne female head struc- Males and females of both races of M. hapla tures, perineal patterns, and stylets. J. NematoL 12: 300-313. have stylets with narrow, pointed cones and 9. Esser, R. P., V. G. Perry, and A. L. Taylor. rounded, set off knobs. Some differences 1976. A diagnostic compendium of the genus were noted in the shape of the stylet shaft Meloidogyne (Nematoda: Heteroderidae) Proc. between the sexes of race B. In race B males Helminthol. Soc. Wash. 43:138-150. the stylet shaft remains cylindrical through- 10. Franklin, M. T. 1972. The present position in the systematics of Meloidogyne. OEPP/EPPO out and often narrows near the knobs, Bull. 6:5-15. whereas in the females the shaft is wider 11. Hussey, R. S. 1979. Biochemical systematics near the knobs. of nematodes--A review. Helminthol. Abstr., Ser. B, Previously, the value of males in root- Plant Nematol. 48(4):141-148. 12. Netscher, C. 1978. Morphological and physi- knot nematode taxonomy has not been em- ological variability of species of Meloidogyne in phasized because of their apparent mor- West Africa and implications for their control. phological variability and scarcity. Males, Meded. Landbouw. Wageningen, Nederland. 78: however, were numerous in most of our 1-46. 13. Sanders, H., and J. Mulet. 1976. 'E' type greenhouse cultures, and head shape and perineal patterns in Meloidogyne species. Nema- stylet morphology of males appear to be tologica 22:373-376. Meloidogyne Male Head Shapes: Eisenback, Hirschmann 521

14. Sasser, J. N. 1979. Pathogenicity, host ranges 18. Triantaphyllou, A. C. 1966. Polyploidy and and variability in Meloidogyne species. Pp. 257-268 reproductive patterns in the xoot-knot nematode in F. Lamberti and C. E. Taylor, eds. Root-knot Meloidogyne hapla. J. Morphol. 118:403-413. nematodes (Meloidogyne species) systematics, biol- 19. Triantaphyllou, A. C. 1979. Cytogenetics of ogy aml control. New York: Academic Press. root-knot nematodes. Pp. 85-114 in F. Lamberti 15. Taylor, A. L., V. H. Dropkin, and G. C. and C. E. Taylor, eds. Root-knot nematodes Martin. 1955. Perineal patterns of root-knot nema- (Meloidogyne species) systematics, biology and con- todes. Phytopathology 45:26-34. trol. New York: Academic Press. 16. Taylor, A. L., and J. N. Sasser. 1978. Biology, 20. Triantaphyllou, A. C., and J. N. Sasser. 1960. identification and control of root-knot nematodes Variation in perineal patterns and host specificity (Meloidogyne species). A cooperative publication of Meloidogyne incognita. Phytopathology 50:724- of the Department of Plant Pathology, North Caro- 735. lina State University, and the United States Agency 21. Whitehead, A. G. 1968. Taxonomy of for International Development. North Carolina Meloidogyne (Nematodea: Heteroderidae) with State Graphics. descriptions of four new species. Trans. Zool. Soc. 17. Triantaphyllou, A. C. 1960. Sex determina- London 31:263-401. tion in Meloidogyne incognita Chitwood, 1949 and 22. Yik, C., and W. Birchfield. 1978. Scanning intersexuality in M. javanica (Treub, 1885) Chit- electron microscopy of perineal patterns of three wood, 1949. Ann. Inst. Phytopathol. Benaki 3:12-31. species of Meloidogyne. J. Nematol. 10:118-122.

Redescription and Lectotype Designation of Tylenchorhynchus cylindricus Cobb, 19131 Stephen A. Lewis and A. Morgan Golden 2 Abstract: Tylenchorhynchus cylindricus is redescribed and illustrated from N. A. Cobb's original specimens collected in 1910. In 1955 M. W. Allen established a neotype from specimens collected near Cathedral City, California. Recently Cobb's original sketches, line drawings, and balsam slides were rediscovered and examined. The specimens collected by Cobb were compared with the neotype established by Allen and with other collections of nominal T. cylindricus. Differences in morphology of the Cathedral City (Allen) and Los Patos (Cobb) populations were observed. Collections of males and females from Cathedral City, California; Mosida, Utah; and Kings County, California; were similar to each other except for some variation in female tail shape. Females in Cobb's collection and in a collection from a beach near Ensenada, Mexico, were similar to each other but differed morphologically from other collections. We consider all collections to represent a range of variation within the species. A lectotype and an allolectotype were selected to establish the taxonomic base for the genus. A ruling has been requested from the International Commission of Zoological Nomenclature on the disposition of the neotype. Key words: taxonomy, morphology, grass.

In 1913 Dr. Nathan A. Cobb erected the (3). Since this material was evidently genus Tylenchorhynchus when he described thought by Allen to have been lost, he es- T. cylindricus found in soil from reclaimed tablished a neotype from a population coastal swamp lands in southern California found in soil near the base of Prunus sp. in Cathedral City, California (1). Specimens Received for publication 3 March 1981. of T. cylindricus from Arvin, Victorville, 1Contribution No. 1882 of the South Carolina Agricul- Yuma Mesa, Modesto, and Stockton, Cali- tural Experiment Station, Clemson University. -"Associate Professor of Plant Pathology and Physiology, fornia; and from Mosida and Duchesne, Clemson University, Clemson, SC 29631; and Nematologist, Utah; also were studied by Alien. Cobb's Nematology Laboratory, Plant Protection Institute, USDA SEA AR, Beltsville, MD 20705. This study was performed measurements, sketches, and ink drawings while the senior author was on sabbatical leave in tile laboratory of Dr. Golden. Appreciation is extended for the fi- of T. cylindricus were on file, but the orig- nancial support of the USDA and for the technical assistance inal specimens recently were found at the of Donna M. S. Ellington, Support Scientist and Paula Crowley, Laboratory Technician. James G. Baldwin, Depart- U. S. Department of Agriculture, Beltsville, ment of Nematology, University of California, Riverside, Maryland. Examination of this material CA 92521; E. Mae Noffsinger, Division of Nematology, Uni- •~ersity of California, Davis, CA 95616; and Adam C. Weiner, and the Cathedral City specimens of Allen California Department of Food and Agriculture, Sacra- revealed differences in both males and fe- mento, CA 95814, provided reference specimens for this study. males.