Autoradiography of Syncytia: Rohde and Mc Clure 69 with relatively heavily-labelled nuclei were 5. DROt'KIN, V. H. 1965. Polyploidy in syncytia of found in roots placed in ~H-thymidine 9 days hairy vetch induced by a Meloidogyne . Nematologica 11:36 (Ahstr.). or more after inoculation. The heavy label was 6. DROPKIN, V. H., and P. E. NEI,SON. 1960, The limited to nuclei of one giant cell of the group, histopalhology of root-knot infections and probably resulted from synchronous in . Phytopathology 50:442-447. DNA synthesis within the cell, since all nuclei 7. HUANG, C. S., and A. R. MAGGENTI. 1969. within the cell appeared to be evenly labelled. Mitotic aberrations and nuclear changes of developing giant cells in Vicia faba caused by root We propose, therefore, that the knot nematode, Meloidogyne javanica. multinucleate giant cells in roots of host Phytopathology 59:447-455. plants infected with M. incognita arise 8, KOSTOFF, D., and J. KENDAI,L. 1930. Cytology through a combination of cell wall of nematode galls on Nicotiana roots. Zentr. Bakteriol. II. Abt. 81:86-91. dissolution, resulting in a coalescence of 9. KRUSBERG, L. R., and L. W. NIELSEN. 1958. adjacent cells, and a series of endomitotic Pathogenesis of root-knot to the Porto divisions. The different patterns of 3H- Rico variety of sweet potato. Phytopathology thymidine labelling in syncytial nuclei formed 48:30-39. 10. MC CLURE, M. A., and 3. ROBERTSON. 1973. late in giant cell development may reflect an Infection of cotton seedlings by Meloidogyne increase in ploidy at a time when the incognita and a method of producing uniformly nematode is completing its final molt. infected root segments. Nematologica 19:428-434. I l, OWENS, R. G., and H. N. SPECHT. [964. Root- knot histogenesis. Contrib. Boyce Thompson Inst. LITERATURE CITED 22:471-490. 12. PAULSEN, R. E.,and J. M. WEBSTER. 1970. Giant I. BIRD, A. F. 1961, The ultrastructure and cell formation in tomato roots caused by histochemistry of a nematode-induced giant cell. Meloidogyne incognita and Meloidogyne hapla J, Biophys. Bioehem. Cytol. 11:701-715. (Nematoda) infection. A light and electron 2. BIRD, A. F. 1972. Quantitative studies on the growth microscope study. Can. J. Bot. 48:271-276. of syncytia induced in plants by root knot 13. RUBENSTEIN, J. H., and R. G. OWENS. 1964. nematodes. Int. J. Parasitol. 2:157-170. Thymidine and uridine incorporation in relation 3. BIRD, A. F. 1972. Cell wall breakdown during the to the ontogeny of root-knot syncytia. Contrib. formation of syncytia induced in plants by root Boyce Thompson Inst. 22:491-502. knot nematodes. Int, J. Parasitol. 2:431-432. 14. SMITH, J. J., and W. F. MAt. 1965. Host-parasite 4. CHRISTIE, J. R. [936. The development of root- relationships of Al[ium cepa and Meloidogyne knot nematode galls, Phytopathology 26:1-22. hapla. Phytopathology 55:693-697.

Scanning Electron Micrographs of the Anterior Region of Some Species of (: Nernatoda)

S, A, SHER and A. H. BELL 1

Ah.stract: Micrographs of the anterior region of 42 species in 36 genera of Tylenchoidea obtained with a scanning electron microscope are prcsenled. Greater detail, depth of focus, and structures not previously seen with the light microscope have been obtained in this study. Some of the implications of the morphology of the face view on the classification of the rlylenchoidca are discussed. Key Words: nematode morphology.

The anterior region of some Tylenchoidea microscope (SEM) to ascertain if additional was examined with a scanning electron information could be obtained to better understand their morphology, classification, Recci~ed tor publication 2 July 1974. and phylogeny. This paper presents ~l>rolcssor of Nematology and Staff Research Associate, l)cpartmcnt of Nematology, University of ('alifornia, Riverside micrographs of 42 species in 36 genera 92502. Appreciation is expressed to I). J. Raski, W. M. Wouts, obtained in this survey and some comments and ~. 1). Van Gundy for rcvicwing tile manuscript and offering ",aluablc comments, and to H..I. Jensen for pro',.iding the on their classification. spccunens of Nacohhodera t hilu oodi. Previous work (2, 5, 6, 7, 8. 9, 11, 22) has 70 Journal of Nematology, Volume 7, No. 1, January 1975

• ::?~!;i

FIG. I-(A-F). A) Psilenchus sp. female (New Zealand) X 7,500. II) Neopsilenchus sp. female (Israel) X 10,000. C) ('lavilenchus sp. female (New Zealand) x I0,000. D) Tylenchus davainii female (California) X 7,500. E) Aglenchus sp. Icmalc (England) X 10,000. F) Cephalenchus sp. female (Australia) x IO,000. Scanning Electron Microscopy/Tylench Anteriors: Sher and Bell 71 shown that much greater detail and depth of indentations dorsally and laterally. Amphid focus can be obtained for surface structures of apertures are a slit along the lateral side of the nematodes with the SEM. In recent papers lip region terminating in a rounded area on (15, 16, 19, 21) SEM micrographs have been the face. There is a single pit (papillae) in each used to supplement light microscope corner of the face. One other population from drawings. New Zealand closely related to T. davainii showed a similar face view though the MATERIALS AND METHODS micrographs were not as clear as the California population. Specimens used in our study were whole Aglenchus (Fig. I-E) shows a large mounts in dehydrated glycerine placed on a rectangular area (oral disc?) clearly delimited glass chip with the anterior end protruding on the face, and large comma-shaped to oval past the edge of the chip. Four to eight amphid apertures, but no pits or papillae are specimens of a single population usually were visible. A population of Aglenchus from mounted on each chip. The body of the Thailand had a similar face view, except for a nematode was secured to the glass chip with a less conspicuous oral disc and more rounded layer of thinned Zut. The chip then was glued amphid apertures. to a SEM mounting stub with the specimens Four populations of Cephalenchus in a vertical position and coated with about (probably C. emarginatus) from Canada and 200 × 10 ~ nm of gold. A JEOL JSM-U3 Australia were similar in morphology (Fig. I- scanning electron microscope operating at an F). The face view is rectangular with an accelerating voltage of 5 to 15 KV was used to indentation dorsally and ventrally, a small examine the specimens and micrographs were round area (oral disc?) is seen clearly around taken with a Polaroid type 55 camera and the rectangular oral opening, four sectors are Polaroid 545 film holder. seen laterally, starting near the center of the face view and extending at right angles RESULTS dorsally and laterally to form a boomerang- shaped structure. A conspicuous pit Six populations of Psilenchinae (papillae?) is located at the distal end of each representing three species in three genera were of these structures. The amphid apertures are examined with the SEM [Fig. I-(A-C)]. slit-like and located laterally between the Psilenchus (Fig. l-A) has a smooth lip region proximal part of the previous structure (Fig. with six pits (papillae?) surrounding the round l-F). oral opening; eight pits (papillae?), two at are represented in this each edge of the face view; and irregular U- survey by the genera Tylodorus and shaped amphid apertures on the lateral sides Doliehodorus. The face views are similar in of the lip region. Neopsilenchus and having a conspicuous oral disc and elongated Clavilenchus (Fig. l-B, C) are similar in longitudinal amphid apertures. Tylodorus appearance, having a smooth lip region with acuminatus (Fig. 2-A, B) has four papillae, six pits surrounding the slit-to-oval oral one in each portion of the rounded slightly opening. Four papillae are located in rectangular face view. Doliehodorus depressions equidistant from each other on nigeriensis and D. silvestris (Fig. 2-C, D) have the side of the lip region; an incomplete annule more conspicuous amphid apertures, the lip or slit is located above each papilla, and, region is indented laterally, and there are no elongated slit-like amphid apertures are papillae. Three additional species of located on the lateral sides of the lip region. have been examined with the Fifteen populations of Tylenchinae SEM, and they are similar to Fig. 2-C, D. identified as belonging to three genera A single population of Tylenehorhynehus (Tylenchus, Aglenchus, and Cephalenchus) phaseoli (Fig. 3-B) shows an oral disc (?) with were examined [Fig. I-(D-F)]. Most of the two indentations laterally where the large specimens produced unsatisfactory results rounded amphid apertures are located, with since they deteriorated under the electron more pronounced indentations dorsally and beam. Micrographs of a fair quality were ventrally; and six protuberances (papillae?) obtained for some of the specimens in seven surrounding the oval oral aperture. The populations. Tylenchus davainii (Fig. l-D) longitudinal ridges of the cuticle are has a rectangular-shaped face with slight prominent in the anterior part of the body 72 Journal q[" Nematology, Volume 7, No. 1, Januao' 1975

(Fig. 3-A). A single population of T. squarish oral disc (?), a round oral opening lamell(ferus (Fig. 3-D) has a large irregular, surrounded by a small depressed area, and

t IG. 2-(A-I)). A) Tvlododorus acuminatus female anterior region (Australia) X 5,000. B) T. acumhmtus female face ic\~ × 5.000. (7) Dolii'hodorus nigeriensis female anterior region (Nigeria) X 2,000. D) Dolichodorus sih'estris female ;interior region (lopotype) × 4.000. Scanning Electron Microscopy/Tylench Anteriors: Sher and Bell 73 irregularly oval amphid apertures. Figure 3-C curvus, and Q. acutus) have been examined. shows the longitudinal lines and the They are all simiLar to the illustrations of Q. longitudinal ridges of the cuticle. acutus (Fig. 4-A, B) and have a four-lobed Four populations of Quinsulcius oral disc (?) with two pits (papillae'?) in each representing three species (Q. capitatus, Q. lobe, round amphid apertures with lip-region

:,-%

FIG. 3-(A-D). A) Tvlenchorhrnchusphaseoli female anterior region (Brazil) × 3000. B T. pha,~'eolitcmale lace view (Bra,'il) ~< 10,000. C) 7~rlenchorhynclms lamell(/brus fem~le anterior region (England) X 3,000. D) 7~ lamelh'l~'ru,~ Icmalc face view (England) × 10.000. 74 Journal of Nematology, Volume 7, No. 1, January 1975 incisures directed toward them, and a slit-like around the oval oral opening, and incisures oral opening with six pits (papillae?), three on directed toward the oral disc. Telotylenchus each side of the oral opening. ventralis (Fig. 6-D) (two populations) has an Merlinius quadrifer (Fig. 4-C, D) (two oral disc (?) similar to Quinsulcius and populations) has a lip region with six goffartL but only one longitudinal incisures, a distinct oral disc and papilla in each lobe, six raised areas and pits almost oval amphid apertures near the (papillae?) surrounding the oval oral opening, anterior end of the lateral lip sectors. The and incisures directed toward the large, anterior region clearly shows the longitudinal rounded amphid apertures. striations of the cuticle (Fig. 4-C). Morulaimus (Fig. 6-E) has a large laterally Three populations of Tylenchorhynchus elongated oral disc with an oval oral opening cylindricus (Fig. 5-A) show an irregular oral with three pits on each side. The anterior disc (?) with rounded amphid apertures at its annule is divided into six sectors, the two edge, a slit-like oral opening, and six minute lateral sectors being smaller than the two pits (papillae?), three on each side of the oral dorsal and two ventral sectors. opening, and distinct lip region annules. T. (Fig. 6-F) has a more set off round oral disc, goffarti (Fig. 5-B) (two populations) has a the lip region is divided into four large sectors four-lobed oral disc (?) with two pits in each (two dorsal and two ventral) and two small lobe (similar to Quinsulcius); a rounded oral lateral sections. The amphid apertures are opening surrounded by six raised areas inconspicuous and located at the lateral lip (papillae?); round, usually obscure, amphid sectors. apertures; and a single distinct incisure Twelve populations belonging to five laterally extending the length of the lip region. species of were examined. Most A single population of Macrotrophurus of the specimens deteriorated under the arbusticus (Fig. 5-C) shows a smooth lip electron beam, but useful micrographs were region with slit-like amphid apertures near the obtained for three species [Fig. 7-(A-C)]. P. posterior area of the lip region, and a round vulnus and P. zeae micrographs (one oral opening surrounded by a small depressed population of each) were of very poor quality. area. Three populations of Paratrophurus P. minyus (Fig. 7-A) has the face view divided (Fig. 5-D) have large round amphid apertures into two small lateral wedge-shaped sectors at the edge of an inconspicuous irregular oral and a large continuous dorsal and ventral disc (?). Three populations of Trophurus (Fig. sector; the oral opening is oval, and 5-E) (Israel, Brazil, and England) show a surrounded by six pits, three on each side. An smooth lip region with only the slightest undescribed species from California has a indication of amphid apertures and oral smooth face view not divided into sectors and opening. Four populations of similar oral opening and pits as in P. minyus Uliginotylenchus rhopalocercus (different (Fig. 7-B). P. thornei (Fig. 7-C) is similar to P. locations in Nigeria) (Fig. 5-F) have an minyus, but the lip region sectors are of inconspicuous oral disc, elongated amphid different sizes and shapes. apertures at the edge of the oral disc, and a Hoplotylus femina (Fig. 7-D) (one round oral opening surrounded by a population) has a smooth face view with the depressed area. anterior annules of the lip region divided Aphasmatylenchus (Fig. 6-A) has a large irregularly and incompletely by incisures, slit- conspicuous oral disc, slit-like amphid like amphid apertures with distal edges apertures at the edge of the oral disc, the directed laterally, and an oval oral opening anterior annule divided into six almost equal surrounded by six pits. sectors, and a slit-like rectangular oral Two populations of Radopholus similis opening. (Fig. 7-E) (Hawaii and Nigeria) have two Telotylenchoides housei (Fig. 6-B) (two lateral lip sectors the length of the lip region, populations) face view morphology is similar with oval amphid apertures anteriorly, and an to Quinsulcius except for the lip region oval oral opening surrounded by six pits, annules which are not directed toward the three on each side. amphid apertures. HistoO'lenchus sp. (Fig. 6- aberrans (Fig. 7-F) has a large C) (one population) has a more rectangular oval oral disc, the anterior annule shows four oral disc (?), no indication of papillae on the large rounded protuberances (sectors), a oral disc, except for the six pits (papillae) slightly oval oral opening surrounded by six Scanning Electron Microscopy/Tylench Anteriors: Sher and Bell 75 indistinct pits, and elongated amphid genera were examined: Hirschmanniella, apertures. Pratylenchoides, Apratylenchoides, and The following additional Zygotylenehus. Most of the specimens

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FIG. 4-(A-D). A) Quinsulcius acutus female anterior region (California) × 3000. B) Q. acutus fcmale face view (Calilornia) x 10,000, C) Merlinius quadr(fer female anterior region (England) X 3,000. D) M. quadr(/er female face ~ie~ (England) X 10,000. 76 Journal of Nematology, Volume 7, No. l, January 1975

Fl(.i. 5-(A-F). A) "Fylenchorhvnchus c)'lindricus female (California) x 10,000. B) 7~vlenchorhynchus gg[/itrti female ~l~racl) X 7,500. C) Macrotrophttrus arh,,~ticola female (France) X 5,000. D) Paratrophttrus sp. female (I hailand) × 5,0011. E) 7)'ophurus sp. female (Brazil) × 7,500. F) Ul~,,inotylenchu,~ rl, opalocercus female (Nigeria) X 5,000. Scanning Electron Microscopy/Tylench Anteriors: Sher and Bell 77

* ..... %5

,~ ' :I ¸ .

FIG. 6-(A-F). A) Aphasmatylenchus nigeriensis female (Nigeria) × 7,500. B1 ttistotylenchus sp. female (Kenya) × 7,51J0. C) Telotylenchoides houseijuvenile (paralype) × 7,500, D) Teloty/enchus ventralis female (Nigeria) × 7,500. E) 31oru/aimus sp. female (Auslralia) × 7,500. F) Behmolaimus hneatus femalc (paratype) × 5,000. 78 Journal of Nematology, Volume 7, No. 1, January 1975

FIG. 7-(A-F). A) Pratylenchus minyus female (California) X 10,000. B) Pratylenchus sp. female (California) × 5,000. () female (California) X 10,000. D) Hoplotylus[ernina female (New Jersey) X 10,000. E) Radopholus similis female (Nigeria) × 7,500. F) Nacobhus aherrans immalure female (England) X 7,500. Scanning Electron Microscopy/Tylench Anteriors: Sher and Bell 79

I-IG. 8-(A-F). A) Rotylenchoides intermedius female (Nigeria)× 10,000. B) hydrophilus female IS~uth Carolina) X 10,000. C) Antarctylenchus humus female (paratype) × 7,500. D) Scutellonema bradys female I Nigeria) × 5,000. E) Peltamigratus so. female (Brazil) × 7,500. F) renzformis immature female (Hawaii) ~< I 0,000. 80 Journal of Nematology, Volume 7, No. 1, Januar.v 1975

FIG. 9-(A-F). A) Hypsoperhwgraminis second-stage juvenile (topotypc) X 12,000. B) Meh~idoL~vnejavanica second- stage juvenile (California) x 12,000. C) Sarisodera hydrophila second-stage juvenile [topotypc) X 7,500. D) lh'l~ddo~h'ra belli second-slage juvenile (topotype) X 7,500. E) Nacohbodera chitwoodi male (topotype)X 3,750. F) N. uhitw~;odiiuvcnile (lopotype) X 5,000. Scanning Electron Microscopy/Tylench Anteriors: Sher and Bell 81 deteriorated under the electron beam, but the slit-like to oval amphid apertures; and an oval following structures of the face view were to rectangular oral aperture. observed on some of the specimens in all of Additional genera of Tylenchoidea these genera: six pits around the oral opening (, , Trichotylenchus, and elongated slit-like amphid apertures Nagelus, and Geocenamus) were similar to Pratylenchus [ Fig. 7-(A-C)]. examined with the SEM; but, because the (Fig. 8) show a pattern of micrographs were of such poor quality, they slit-like to oval amphid apertures at the lateral are not included. Genera which show some edge of a large round to oval oral disc, and a evidence of being closely related to some of conspicuous oval oral opening. Specimens these genera, but usually not included in the usually did not deteriorate under the electron Yylenchoidea (Nothanguina, Boleodorus, beam. Helicotylenchus (Fig. 8-A), Nothotylenchus, and Deladanus) also Rotylenchoides (Fig. 8-B) and deteriorated under the electron beam in initial Antarctylenchus (Fig. 8-C) have no attempts to obtain micrographs. longitudinal incisures of the lip region. Scutellonema (Fig. 8-D), Peltamigratus (Fig. DISCUSSION 8-E) and Rotylenchulus (Fig. 8-F) have the anterior lip annule divided into six sectors. No The face view of Tylenchoidea as seen with pits (papillae) are seen on the face view of the scanning electron microscope shows that these species, or any of the other the true surface morphology usually has not Hoplolaimidae examined (19 species in eight been seen with the light microscope. This genera) with the SEM. study and some previous work (20) show that Second-stage juveniles of six populations of morphological structures of the face view Meloidog.vne and one population of appear to be constant for some taxa at the ttypsoperine representing four species were specific (20), generic, and higher categories. examined. Although most of the specimens This additional morphological information deteriorated under the electron beam, provides some exciting material for micrographs of fair quality were obtained for understanding the morphology, three species of Meloidogyne (Fig. 9-B) and classification, and relationships of the the Hypsoperine species (Fig. 9-A). They all Tylenchoidea. The following discusses some showed a pattern of a large dumbbell-shaped implications of these preliminary studies for oral disc (?) with elongated conspicuous the Tylenchoidea. amphid apertures at the lateral edges, and a The genera of Psilenchinae and round to oval oral opening surrounded by six Tylenchinae studied (Psilenchus, pits. Neopsilenchus, Tylenchus, Aglenchus, and In contrast to Meloidogynidae, second- Cephalenchus) have distinctive face view stage juveniles of withstood patterns that can be distinguished by SEM the same accelerating voltage used with micrographs. Neopsilenchus and Meloidogyne without deteriorating. One Clavilenchus face view micrographs are population each of two genera was examined. similar and support the synonomy of these Sarisodera (Fig. 9-C) has a large oval labial genera. disc, slit-like amphid apertures at the edge of Tylodorus and Dolichodorus micrographs the labial disc, conspicuous oval oral of the face view agree with the speculation aperture, and the anterior annule of the lip proposed by Meagher (10) that "Tylodorus region is divided into four sectors, the lateral seems to occupy a systematic position sectors being considerably smaller. between Tylenchus and Dolichodorus." Meloidodera belli (Fig. 9-D) has a large Six species of Tylenchorhynchinae, in three irregularly oval labial disc, slit-like amphid genera, all show a different pattern for the face apertures, a conspicuous rounded oral view (Fig. 3; 4-A, B; 5-A, B, F). aperture, and the anterior annule of the lip 71~'lenchorhynchus goJfarti (Fig. 5-B) appears region is divided into six, almost equal similar to Telotylenchus ventralis (Fig. 6-D) sectors. in the family . The recently described Nacobhodera Tylenchorhynchus cylindricus (Fig. 5-A), T. ( Fig. 9-E, F) has a large dumbbell-shaped oral phaseoli (Fig. 3-B) and Quinsulcius acutus disc with four pits (papillae?), one each near (Fig. 4-B) also show some similarities to the lateral edges of the oral disc; conspicuous Histotylenchus sp. ( Fig. 6-B), 82 Journal of Nematology, Volume 7, No. 1, January 1975 Telotylenchoides housei (Fig. 6-C) and The face view of Nacobbus is not similar to Telotylenchus ventralis (Fig. 6-D) in the other Pratylenchidae studied, which supports family Belonolaimidae. the recent transfer of this taxon from the Aphasmatylenchus nigeriensis (Fig. 6-A) Pratylenchidae (3). has a face view similar to the basic pattern The second-stage juvenile specimens of seen in the Hoplolaimidae (Fig. 8). It is also Meloidogynidae and Heteroderidae species one of the few species in which the face view appear to differ primarily in the presence of pattern as seen with the light microscope (14) six pits (papillae?) around the oral opening in is similar to the SEM micrographs. Meloidogyne, the shape of the oral disc, the Merlinius quadrifer (Fig. 4-C, D) exhibits a segmentation of the anterior lip annule, and pattern similar to micrographs previously the reaction to the electron beam in the SEM. reported for Merlinius joctus and M. Further study of other stages and additional microdorus (15). species are needed. The three genera in the subfamily The two genera of Heteroderidae examined Trophurinae all show different patterns [Fig. (Fig. 9-E, F) can be distinguished from 5-(C-E)]. The four populations (Brazil, Israel Heterodera (21) by SEM micrographs. and England) of Trophurus sp. examined Sarisodera (Fig. 9-E) and Meloidodera (Fig. were all similar in that they did not show any 9-F) micrographs are similar to structures on the smooth lip region, not even Hoplolaiminae face view micrographs (Fig. 8) the amphid apertures or oral opening (Fig. 5- and support the theory of Wouts and Sher E)~ that evolved from a Hoplolaimidae are considered to have a Hoplolaiminae (23). They considered basic pattern of a conspicuous round to oval Meloidodera the most primitive oral opening without associated pits (papillae) Heteroderinae because of morphological and a large round to oval oral disc with the characters that they have in common. The amphid apertures at the edge of the oral disc face view of Meloidodera belli (Fig. 9-F) (Fig. 8). A further division of the appears to be, of all the Heteroderinae studied Hoplolaimidae can be made on the basis of by SEM, the most closely related to the anterior lip annule. Helicotylenchus, Hoplolaiminae (Fig. 8). Rotylenchoides, and Antarctylenchus [Fig. 8- The micrographs of Nacobbodera (Fig. 9- (A-C)] have an undivided anterior annule (no E, F) show a related, but different, pattern longitudinal lines on the lip region) and the than Meloidogynidae or Heteroderidae. The rest of the genera have the first annule divided face view shows no similarities to Nacobbus, into six sectors (longitudinal lines on the lip and therefore does not support the region) [Fig. 8-(D-F), 3, 7]. This supports the classification of this genus as being most classification of Siddiqi (17) but not the closely related to Nacobbus (4). Meloinema classification of Golden (3). which appears to be similar to Nacobbodera The Belonolaimus lineatus face view (Fig. (the latter may be a synonym of Meloinema) 6-F) appears similar to micrographs was placed by Choi and Geraert in the family published for Belonolaimus longicaudatus Meloidogynidae (1). Specimens of (18). The papillae reported by Roman (12) on Meloinema have not been available for study, the lip region for Belonolaimus lineatus, B. but the results with Nacobbodera would longicaudatus, and B. gracilis are not seen support the placement of Meloinerna with the scanning electron microscope. (=Nacobbodera?) in the Meloidogynidae. Morulaimus micrographs of the face view Additional comments and speculations on are similar to those published for the original the morphology, classification and phylogeny description of the genus (! 3) except for the six of the Tylenchoidea are being postponed pits (papillae) surrounding the oral opening. because additional SEM work is still in This can be used as additional information to progress to confirm and expand these studies. separate Morulaimus from Belonolaimus. Pratylenchidae face views all have six pits LITERATURE CITED (papillae) surrounding the oral opening, and this appears to be a good character to help 1. CHOI, Y. E., and E. GERAER'[. 1973. Description of Meloinema kerongense n. g. n. sp. (Nematoda: define this taxon. This provides justification Meloidogynidae) from Korea. Nematologica for the placement of Hoplotylus in the 19:334-341. Pratylenchidae (3). 2. ELLENBY, C., and E. M. WILSON. 1969. Scanning Scanning Electron Mieroscopy/Tylench Anteriors: Sher and Bell 83

microscope observations on the spear tip of 13. SAUER, M. R. 1966. Morulaimus, a newgenus of the second-stage larva of Heterodera rostochiensis. Belonolaiminae. Nematologica 11:609-618. Nematologica 15:290-291. 14. SHER, S. A. 1965. Aphasmatylenchus nigeriensis n. 3. GOLDEN, A. M. 1971. Classification of the genera gen., n. sp. (Aphasmatylenchinae n. subfam.: and higher categories of the order Tylenchida Tylenchoidea: Nematoda) from Nigerian soil. (Nematoda). Pages 191-232 in B. M. Zuckerman, Proc. Helminthol. Soc. Wash. 32:172-176. W. F. Mai and R. A. Rohde, eds. Plant parasitic 15. SHER, S. A. 1973. The classification of Tetylenchus nematodes. Vol. I. Academic Press, New York. Filipjev, 1936, Leipotylenchus n. gen. 4. GOLDEN, A. M., and H. J. JENSEN. 1974. (Leipotylenchinae n. subf.) and Triversus n. gen. Nacobbodera chitwoodi n. gen., n. sp., (Nematoda: Tylenchoidea). Nematologica 19:318- (Nacobbidae: Nematoda) on Douglas fir in 325. Oregon. J. Nematol. 6:30-37. 16. SHER, S. A. 1974. Sauertylenchus labiodiscus n. 5. GREEN, C. D. 1967. Preparation of nematodes for gen., n. sp., from Australia (Nematoda: examination under the stereoscan electron Tylenchorhynchinae). J. Nematol. 6:37-40. microscope. Nematologica 13:279-282. 17. SIDDIQI, M. R. 1971. Structure of the oesophagus in 6. GREEN, C. D. 1971. The morphology of the terminal the classification of the superfamily Tylenchoidea area of the round-cyst nematodes, S. G. (Nematoda). Indian J. Nematol. 1:25-43. Heterodera rostochiensis and allied species. 18. SMART, G. C., JR., R. D. HARTMAN, and T. C. Nematologica 17:34-46. CARLYSLE. 1972. Labial morphology of 7. DE GRISSE, A. T. 1973. A method for preparing Belonolaimus longicaudatus as revealed by the nematodes and other soft tissues for scanning scanning electron microscope. J. Nematol. 4:216- electron microscopy. Meded. Fac. Landbouwwet. 218. Rijksuniv. Gent 38:1685-1695. 19. SPRAULL, V. W. 1972. Antarctenchus hooperi n. 8. DE GR1SSE, A., and A. LAGASSE. 1969. gen., n. sp. (Nematoda: Dolichodoridae) from L'utilisation du microscope eqectronique a Signy Island, South Orkney lslands, with the balayage dans l'Etude des nematodes. J. Microsc. erection of a new subfamily. Nematologica 18:353- 8:677-680. 359. 9. HANDSCHIN, G. 1971. Untersuchung von 20. STONE, A. R. 1972. The round-cyst species of Nematoden mit dem Raster- Heterodera as a group. Ann. Appl. Biol. 71:280- Electronenmikroskop. Rev. Suisse Zool. 78:574- 283. 575. 21. STONE, A. R. 1973. Heterodera pallida n. sp. 10. MEAGHER, J. W. 1963. Tylodorus acuminatus n. g., (Nematoda: Heteroderidae), a second species of n. sp. (Nematoda: Tylenchinae) from Eucalyptus potato cyst nematode. Nematologica 18:591-606. forest in Australia. Nematologica 9:635-640. I 1. MULVEY, R. H. 1974. Cone-top morphology of the 22. STONE, A. R., and C. D. GREEN. 1971. A simple white females and cysts of the genus Heterodera method of preparing nematodes for scanning (subgenus Heterodera), a cyst-forming nematode. electron microscopy. Nematologica 17:490-491. Can. J. Zool. 52:77-81. 23. WOUTS, W. M., and S. A. SHER. 1971. The genera 12. ROMAN, J. 1964. Belonolaimus lineatus n. sp. of the subfamily Heteroderinae (Nematoda: (Nematoda: Tylenchida). J. Agric. Univ. P. R. Tylenchoidea) with a description of two new 48:131-134. genera. J. Nematol. 3:129-144.