On the genus Dilylenchus Filipjev, 1936 (Nernatoda : )

Renaud FORTUNER* Laboratoire de Nématologie, ORSTOM, BP V-51, Abidjan, Côte d’Ivoire.

SUMMARY.

Several populations of myceliophagus from Ivory Coast and Upper-Volta were studied for variability of generic and specific taxonomie characters, which was found to be greater than generally accepted.Ditylenchus is redefined ; Chitinotylenchus isconsidered genus inquirendum; Diptenchus and Safianema are synonymized with Ditylenchus ; Pseudhalenchus is considered a valid genus under Tylenchinae; Pseudhalenchinae is synonymized with Xylenchinae. Ditylenchus geraerti is synonymized with D. myceliophagus. The following new combinations are pro- posed : Ditylenchus indicus for Pseudhalenchus indicus; Ditylenchus acutus for Pseudhalenchus acutus; Ditylenchus khani for Diptenchus indicus; Ditylenchus lutonensis for Safianema lutonense; D. anchilisposomus for S. anchilispo- somum; D. damnatusfor S. damnatum; S. hylobii is transferred backto Pseudhalenchus. Four are considered species inquirendae :Ditylenchus bacillifer, D. intermedius,D. humuli and D. karakalpakensis. Chitinotylenchus para- gracilis, is considered species incertae sedis. A tabular keyto the validspecies of Ditylenchus is presented.

RÉSUMÉ

Le genre Ditylenchus Filipjev, 1936 (Nematoda : Tylenchida) Plusieurs populations deDitylenchus myceliophagus de Côte d’Ivoire et de Haute-Volta ont été étudiées; la varia- bilité des caractkres taxonomiques utilisés aux niveaux générique etspécifique s’est montrée plus grande quegéné- ralement admis. Ditylenchus est redéfini ; Chitinotylenchus est considéré comme genus inquirendum; Diptenchus et Safianema sont synonymisés avecDitylenchus; Pseudhalenchus est considéré comme un genre valideappartenant aux Tylenchinae ; la sous-famille des Pseudhalenchinae est synonymisée avec celle des Tylenchinae.Ditylenchus geraerti est synonymisé avec D. myceliophagus. Les combinaisons nouvelles suivantes sont proposées : Ditylenchus indicus pour Pseudhalenchus indicus; Ditylenchus acutus pour Pseudhalenchus acutus; Ditylenchus khani pour Diptenchus indicus; Ditylenchus lutonensis pour Sa fianema lutonense; D.anchilisposomus pour S. anchilisposomum; D. damnatus for S.darnnatum; S. hylobii est retransféré à Pseudhalenchus. Quatre espèces sont considérées comme species inqui- rendae : Ditylenchus bacillifer, D. intermedius, D. humuli et D. karakalpakensis.Chitinotylenchus paragracilis est considéré species incertae sedis. Une clé tabulaireest présentée pour la détermination desesphces valides de Ditylenchus.

Nematodes of the genus Ditylenchus were variable and only a few were constant enough observedfrom diseased ricepanicles inthe to be used for taxonomic purposes. A search of Ivory Coast and it was thought, at first, that the literature revealed that similarvariability they might be responsiblefor the poor condition exists in atleast several other species of the of the rice. However, a study of their morphol- genus. ogypermitted their identification as D. Inyce- This led the ahthor to question the validity Ziiphagus Goodey, 1958, a well knownfungus of the species described under Ditylenchus and feeder. also of the genera closely related to this taxon. Duringthese studies, it was observed that As norecent review of thegenus has been manymorphometrical characters were highly published, a tabular Bey to the valid species in

* Present Address : Department of Food and Agriculture, Laboratory Services/Nema Lab., 1220 N Street, Sacra- mento, California 95814, U.S.A.

Revue Nématol. 5 (1) : 17-38 (1982) 17 R. Fortuner

Ditylenchus was constructed,using only the Theobservations were made using a Leitz reliablecharacters. Brzeski (1981) recently Ortholux II microscope at 1 O00 x magnifica- proposeda revised classification of thefamily tion,in bright field microscopyor with an (including Ditylenchus) and his interferencecontrast device of Nomarski. For article was used as a framework forthe present measurement purposes, drawings were made of study. al1 specimens using a drawing attachment or a AnguininaeParamonov, 1962was raised to cameralucida, both systems set to give an familyrank by Siddiqi (1971) andto super- additional enlargement factor of two. family rank by Siddiqi(1980b). The status of thisgroup will not bediscussed here andits lowest rank (Anguininae) 'will be used. Results

OBSERVATIONSMADE ON THE SPECIMENS Materials and Methods Table 1 (females) presents,for the four samples observed,the body length, stylet length, dis- Thestudied specimens were obtainedfrom tancefrom anterior end to hemizonid and to the localitiesfollowing : , excretorypore, length of oesophagus (tothe Sample 1 - Thirty females and twenty males oesophage-intestinal junction and to the end of fromupland ricepanicles (cv.Iguape Cateto) glands),length of tail,anal and vulval body sent in1976 by A. Pouzet (ORSTOM agronomist) from A.V.B. (Autorité pour l'Aménagement de diameters, distance from head to vulva, length of anteriorgenital branch and of post uterine la Vallée duBandama) fields atFitabro 1 sac(P.U.S.), and distance between vulva and (bloc C, plot 7.04), in the Ivory Coast. anus. Table 2 presents the same characters for Sample 2 - Sixindividuals from sample 1 were inoculated into a test tube containing the males in samples 1, 2 and 4, with bursa, testis, spiculeand gubernaculum lengths in place of fungus Colletotrichum gloeosporioides Penz. on the female genital characters. For every charac- -dextroseagar. After three weeks, the ter, the meanis given with itsconfidence interval tube wasfound ta contain 120specimens of Ditylenchus of whichfifteen females and eight (i = $ ) therange and the coeRcient of males were selected for morphological studies. Sample 3 - Six females from an A.V.B. field variability. at Assakra 1, a village close to Fitabro 1. Figure 1 presents graphically the correlations Sample 4 - Nine females and five males from betweenthe constituents of the usualratios soil aroundroots of sugarmne at Banfora (a, b, c, c', and V) and post-uterine sac length (Upper-Volt,a) in the SOSUHV (Société Sucrière in relation to vulva-anus distancefor the females de Haute-Volta) fieldscollected by P. Cadet. in samples 1 + 2. Some morphological features Twofemales and onemale were also observed are illustrated in Figures 2 and 3. fromforest soilfrom Taïforest, in the Ivory Coast. DISCUSSIONON THE VARIABILITY OF SOME, The specimens wereBilled by FP 4:l (Netscher MORPHOMETRICAL CHARACTERS & Seinhorst,1969), fixed in 4% formaldehyde and mounted in glycerin on Cobb slides. Orcein General morphology wasadded during the mounting process for coloring the . A few individuals from Habitus. In the present specimens, the body sample 2 were observed in pure water, just after was almost straight or slighly C-shaped, usually beingkilled bygentle heat, ta observesome wit.h a bend located in the vicinity of the vulva inconspicuousfeatures (median oesophageal (Fig. 2 A, B). bulb valve for instance). Some females were also Body length. Thebody length was highly observed in cross-section in glycerin. variable (Tab.1) ; it ranged from 600to 1 200 prn -. . -. . - . . - __ .- . . - .~. - - ~ - . - _.. . _- 18 Revue Nématol. 5 (1) : 17-38 (1982) Genus Ditylenchus

. ... 1001

I.1

500 y = 13 X +41 r = 0.7730

- 5'0 9'0 T c

VA1

1OOC 100

500 50

Db

20 r = 0.7833

Fig. 1. Ditylenchus myceliophagus. Graphic representation of ratios a, b, c, CI, V, and post-uterine sac in relation to vulva-anus distance andto body diameter. L : body length ; Dv : body diameter at levelof vulva ; œ : length of oesophagus ; T : tail length ; HV : head to vulva distance ; VAN : vulva to anus distance; Da : body diameter at level of anus ; PUS : length of post-uterine sac ; y = f(x): equation of the regression lines ; r = coescient of correlation (n = 45 ; r significant above 0.380 at 1y0 level). in sample 1, 700 to 1 400 pm in sample 4, with size might also be caused by different ecological meanvalues of 800-850 pm. Sample 3 was environment,individuals fromrainforest (Taï) smaller,with a mean value of only 546 Pm. being slnaller (400 and 575 pm) than those from Brzeski (1967) andEvans and Fisher (1970) have savanna regions (A.V.B. fields and Upper-Volta, shown that the body lengtb of D.rnyceliophagus samples 1 to 4). depends on the food supply and the nature of Bodydiameter. Thebody diameter also had thefungus on wbich it feeds.Hesling (1974) ahigh variability in the present specimens gave a range for body length inD. myceliophagus (Tab. 1).Brzeski (1967) observed no statistical of 600-1 380 Pm.Goodey (1952), Thorneand difference in width in specimens of D. mycelio- Allen (1959), and Wu (1960b) observed that in plzagus but itshould be noted that he measured D. destructor thebody length varies greatly this character only at pharynx and anus levels. depending on the plant host. Differences in body Goodey (1952), whileobserving thatin, D.

Revue Nématol. Revue 5 (1) : 17-38 (1982) 19 R. Fortuner

Revue Ném.atol. 5 (1) : 17-38 (1992) Genus Ditylenchus destrucfor generallythe longer the worm, the specimens, almost invisible in most of the body, fatter it is, reported some variation related to more marked just below the lip region. thehost. A population from mint was of the Phasmids. Phasmids were not observed in the same length but much slimmer than a popula- present specimens asis generally the case in tion from potato. Difylenchus and the Anguininae. Phasmids were Ratio“a”. Thecorrelation of thetwo con- reportedin D. nortorzi andin the malesof stituents of ratio “a”was studied fromspecimens D. emm. from thetwo samples 1 and 2 (grouped).The Deirids. Thedeirids were present, slightly correlation isgood and the regression line almost posteriw to the level of the hemizonid. passes through the origin (Fig. 1). Wu (1960b) Lateral field. The lateral field wascomposed showed thatin D. desfructor, althoughbody of generallysix (Fig. 2 E), morerarely seven length and diameter are highlysignificantly cor- (Fig. 2 F) or eight (Fig. 2 G) lines, best seen in related, the regression line did not pass through cross section. In D. destructor, usually with six the origin.The coefficient “a”cannot be used lines,five additional lines can sometimes be in al1 cases. Filipjev (1936a) differentiated Dity- seen, formed by the crestsof the cuticular folds, lenchus as being slimmer than Anguina. How- between the typicallines (Thorne & Allen, 1959 ; ever, in view of the variability of this character Wu, 1960a). Alternatively the lines candisap- under varying external’conditions, it should not pearcompletely in the stretched cuticule of be used for taxonomic purposes. stout egg-producingfemales (Thorne & Allen, Lips. Scanningelectron microscope photo- 1959). The greater numberof lines in D. destruc- grapbs of D. dipsaci and Anguina sp.in the tor cannot be tied, tbrough a wider girth, to the photograph collection of theUniversity of greater development of the genital branch in this California,Riverside, kindly communicated by species,because D. dipsaci, whichalso has ArnoldBell, havelips as around disc not enlargedovary, possess onlyfour lines. The separated into labial sectors. The character “lip number of lines is very constant in species like separate” used in the key by Andrassy (1976) D. dipsaci with four lines, and, in spite of the for differentiating Anguinidae from Tylenchidae variability of this character in specieslike D. and Psilenchidae is not supportedby the present myceliophagus or D. destructor with six to eleven observations. The head of the present specimens lines, it can be used for identification of species. was continuous with the body, anteriorly flat- Tail length. Tail length was highly variable tenedand cap-like, and devoid of lip annula- (Tab. 1). The general shape of the tail was also tions when seen in brigbtfield microscopy. Using variable. It was more or less conical with often aninterference, contrast device of Nomarslry, aslimmer posterior part. It couldbe straight two or three very faint annules couldbe seen (Fig. 2 H), slightly bent (Fig. 2 1) or bent at an in somespecimens . (Fig. 2 C). Wu (1960~) angle of 900 (Fig. 2 J) or more (Fig. 2 K). observed at highmagnification a fewfine Tailshape wasused byThorne (1949) to annulesin the lips of D. destructor, a species separate Tylenchus s.1. with tail filiform, greatly originally described by Thorne (1945) as having elongated, from Ditylemhus with tail conoid. In smooth lips.Some species in Ditylenchus (D. fact,the variability of thischaracter, both friformis forexarnple) have more marked lip within specieslike D. myceliophagus or D. annules, butthis character is too diEcultto destructor andamong species of thevarious observe to be used in routine identifications. genera under Tylenchinae, precludes its use for Theabsence of lipannulation wasused by differentiation of the higher taxa. Wu (1967a) Thorne (1949) to differentiate Ditylenchus from recognized Ditylenchus withtail conoid to Tylenchus. Lipannules are difficult to see in elongate-conoid and Tylenchus s.1. withtail some Tylenchus s.1. (Wu, 1967a). Tbeyare elongate-conoid to filiform. Tail extremity (used present,even if veryfaint, in at least some by Hesling, 1974, as a discriminating criterion species in Ditylenchus. Thischaracter should for D.myceliophagus) .was more constant, being not be used at higher levels of the classification. roundedin every individual observed. Wu The body annuleswere very faint in the present (1960b)observed the shapeof tail of D. destructor

Reuue Nématol. 5 (1) : 17-38 (1982) 21 Fig. 2. Ditylenchus rnyceliophagus. A-M : females ;.N-O : males ; population 1. A. Large female, L = 1.3 mm ; B. Small female, L = 0.680 mm ; C. Anterior end, abutting oesophageal glands ; D. Anterior end, dorsal oeso- phageal gland overlapping intestine ; E-G. Lateral field, E : 6 lines, F : 7 lines, G : 8 lines ; H-K. Posterior ends, H : tail straight, 1 : tail slightly bent, J : tail bent, K : tail sharply bent ; L-M. Ovaries, L : spermatheca and post-uterine sac empty, M : spermatheca with sperms, post-uterine sac filled with granular material. N-O : male tails. . -- .~ .~ ~ -- .- ." . - - - _-- 22 Revue Nématol. 5 (1) : 17-38 (1982) Genus Ditylenchus

to be somewhat variable depending on the host. outby Paramonov (1970), many species in However, al1 tailsillustrated in Fig. 1 of Wu Tylenchinae have protractors attached directly (1960b)have a narrowly rounded extremity.’ to the subcuticle of the cephalic capsule. Mheiri (1972) gave illustrations of tails of eleven Oesophagus. Theoesophagus length was not specimens of D. destructor. Ten have the rounded correlatedto the body length (Fig. 1). Wu end typical of the species, one is pointed. (1960b)noted the same phenomenon for D. Pointed tails seelns a constant feature of some destrucfor. Coefficient b must not be calculated. other species (for example D. dipsaci). Broadly Inthe present specimens, theprocorpus was rounded or sickle-shaped extremities are charsc- thin, the median bulb fusiform, the isthmus long . teristic of other species. Veryfew species are andthin and there were no thickeningsor describedwith intermediate tail ends (i.e. constrictionseither between procorpus and pointed to minutelyrounded) and, those ex- median bulb or between isthmus and glandular cepted, shape of tailterminus is both reliable bulb (constrictions appear in several genera of and useful for specific differentiation. Anguininae, see Brzeslri, 1981). In the present specimens, the tail lengtll was correlatedboth with the body length (coef- Median bulb. The median bulb was situated ficient c) and the anal diameter (coefficientc’) not at mid-length of the oesophagus but closer andthe regressionlines passedthrough the t o the anterior end (Fig. 2 Cl D). In the median origin (Fig. 1). bulb, weak thickenings were present but impos- Wu (1960b) observed that, in females of D. sible to observe in some fixed specimens. For a deslructor, the correlation between body and tail casualobserver the present specimens of D. lengths was not significant.The coefficient c myceliophagus wouldappear to belong tothe cannot be used in al1 cases. genus Nothotylenchus, which differs from Dity- lenchus only by the absence of refractive thiclre- nings in the median bulb. The study of indi- T12e digestive sysfem viduals freshly killed and temporarily mounted Stylet. Thestylet is wealt (character of the inwater was necessary to decide of thetrue sub-family), with small knobs rounded and well identity of the . The present specimens separated (Fig.2 C, D). In the present specimens, areintermediate between the species in Dity- themean stylet length was 7 to 7.5 pm (the lerzchus with strong thicltenings (for example D. range was 6.5 to 8.5 pm), with very little varia- dipsaci) andthe species inthe genus Nothoty- tion(Tab. 1). Brzeski(1967) observedsimilar Zenchus. Several worlters (Surnenlrova, 1975 and values,and no variation, in styletlengths of Geraert, 1976 in Brzeski, 1981) suggested that D. rnyceliophagus reared on two different fungi. Nothotylenchus is probably synonymous to Dity- Hesling (1974) indicates that stylet length does lenchus. Theabove observations tends to sup- Vary a little in D. nzyceliophagus but it never port this opinion, but the genus Notlzotylenchus reaches 10 pm. will haveto be reviewedbefore any definite

Some other ~ Ditylenchus spp. also have small move can be done. stylet., less than 9 pm long (Tab. 3), while other Oesophageal glands. The shape of oesopha- have, stylet 10 pm or longer (and among ihese, geal glands was very variable. Individuals were D. dipsaci and D. desiructor). Very few species observedwith anabutting basal bulb, others presentintermediate values (Tab. 3). This with overlapping glandular lobes. In the latter constantcharacter is veryuseful for species case,position of overlapwas either lateral, identification. ventral or dorsal and its length varied greatly, CephaZicframework. Filipjev (1936~)noted up to 44 pm (Fig. 2 C, D and Fig. 3). “head without chiiinization” for Ditylerzclzus. In Thorne and -411en (1959) observed an overlap- fact the cephalic framework is alwayspresent ping lobe in D. deslructor. In the specimens from and sclerified inthis genus, but rather weak. potato the overlap was dorsal, butit was ventral The protractormuscles of the stylet are attached inthe specimens frombulbous iris. Brzeslti to the basal plate of theframeworlt, as in al1 (1967) foundthat thesize of the oesophageal lobe members of Anguininae (Fig. 2 C, D). As pointed clepended onthe fungus host up,on which D.

Revue Nématol. 5 (1) : 17-38 (1982) 23 R. Fortuner

I! \ B

Fig. 3. Ditylenchus,myceliophagus.Variability of oesophageal glandular lobe. A : Juvenile, second stage, six day- old, with lateral overlap,B : Female fourteen day-old, ventral overlap; C : Female fourteen day-old, dorsal over- lap ; D : Female nine day-old, very reduced overlap; F & G : two views of the samespecimen, female eight.day- old ; F : appearance of an abutting oesophageal bulb ; G : actual lateral overlap, V : oesophago-intestinal junc- tion. Al1 arrows from ventral side.

myceliopaghus was feeding.The overlap was dorsally(Fig. 3 C). Thisnever appears in' eitherdorsal or ventral. In Iran, D. desirucior juveniles nor in young females, but only in two had glands overlapping the intestine slightly to males and eleven older females. (iu) A shortened considerably, on dorsal, ventral or lateral sides overlap(Fig. 3 D) wasseen inseven older of the body(Kheiri, 1972). This considerable females. (u) Very rarely, the shortening was so variation of the oesophagealglands in D. des- pronounced thatthe overlapdisappeared al- trucfor was used by Kheiri (1972) and Geraert together(Fig. 3 E). Thiswas never seen in and Kheiri(1970) topoint out the similitude juvenilesor young females, butin two older between this species and Pseudhalenchus anchi- females and onemale. Sometimes the gland lisposomus Tarjan, 1958. appeared to lie in an abutting bulb, but examina- In the present specimens, in order to clarify tion from the opposite siderevealed the oeso- thearrangement of the oesophagealglands, phago-intestinalvalve lying hidden behind a 70individuals (fourteen juveniles, fourteen long lateral overlap (Fig. 3 F, G). males, five young females(less than ten-day- Intestine. No cardiawas observed between old),' 37 older females) were observed from test oesophagus and intestine in the present speci- tubesinoculated with two juveniles each and mens,but the anterior intestinal cellswere extracted one to 49 daysafter inoculation. It hyalineasdescribed by Brzeski(1981) for wasfound that : (i) Inyoung specimens, the members of Anguininae. In individuals with a basic pattern is a long lateral overlap (Fig. 3 A). longoesophageal overlap, theintestine along This wasobserved intwelve juveniles, eight the overlap was sometimes thinner, probably to males, and four young females. (ii) This pattern makeroom for this structure, and then the isoften modified byaventral shift of the lumen of theintestine was indistinctand dif- overlap, (Fig.3 B) observed in older individuals : ficult to see (Fig. 2 D). A similar condition was two juveniles,fifteen older females, andthree described by Siddiqi (1980a) for his new genus

- .-males. .@i) More rarely, the wwlapwas shifted.. -Safianema. . -_ ~. __ ~ ~ - 24 Reuue Némafol. 5 (1) : 17-38 (1982) Ganus Ditylenchus

The genital a.pparatus Spermatheca. The spermathecae of the present specimenswere elongate, tubular, in line with The ovary. In the anterior genital branc.h of the genital tract, and usually full of sperm cells presentfemale individuals (whether young or (Fig. 2 L, M). The shape of the spermatheca was old)the ovary was always straight and never used by Wu (1967~)to differentiate Ditylenchus reached the base of oesophagus (Fig. 2 A, B). (with spermatheca a tubular structure between One specimen of D. rnyceliophagus from fungus uterus and oviduct) from Tylenclzus s.1. (sperma- culturefrom Antibes (France) had long,a theca,when present, adiverticulum at tl1e reflexed ovary. can be noted that long and It junction of the uterus and the oviduct). Some reflexedovaries reachingpast the end of the Species (D. brassicae, D. cyperi, D. deiridus) have oesophagus are found in several plant parasitic short,rounded spermatheca, in linewith tl1e species (0. dipsaci, D. angustus, D. destructor), genital tract.’ whereasthe mycophagous (D. myceliophagus andothers) have shorter, straight ovaries. Colurnella.(2)The columella was short (Fig. 2 Paramonov (1970) also linksthe long reflexed N, O) and composed of four rows of four cells as ovaries of solne Ditylenclzus totheir patho- typical in Ditylenchus. Brzeski (1981) placed genicity to plants. The relationship may prove great emphasis on the structureof the columella to be constant but, for the moment, the hypo- for separating the genera within Anguininae. thesis must rest until more is known about the The columellawas followed by a group of feeding habits of a majority of species of Dity- closely packed cells. Thisstructure was called lenchus. Whateverthe cause of thegreater asphincter by Brzeski (1981). Itsfunction is length of the ovary in the plant parasiticspecies unknown. of Ditylenchus, this character is highly variable. Post uterine sac. The posterior genital branch Goodey (1952) noted that in D. destructor, the was reduced to a post-uterine sac (P.U.S.). The size of the gonads of both sexes was influenced length of this structure is variable (Tab. 1). It by the host. Thorne and Allen (1959) observed is correlated to the vulva-anus distance but the that the number of oocytes in the ovary of D. regression line does not pass through the origin destructor varied with the host, from a dozen in (Fig. 1). Theratio P.U.S./vulva-anus distance specimens from sugar beetto “scores” of oocytes cannot be used. It is also correlated to the body in specimens from potato and sweet potato. Wu diameter at vulva, and here the regression line (196Ob) noted that reflexion of the. tip of the passesthrough the origin (Fig. 1). It isnot ovary in D. destructor occurred “in a few cases” lmownwhether this isalso the case for other in specimens from bulbous iris,and only once in species in Ditylenclzus. In the present specimens, 25 specimens from dahlia. the P.U.S. was about three body diameters long. Inthe present specimens, the oocytes were Studying theinfluence of the host on the dimen- arranged in. the ovary in one or two rows. D. sions of D. destructor, Goodey (1952) noted the destructor hasoocytes paired or in single file “relative constancy” of the length of the P.U.S. dependingon the host (Wu, 1960b). No taxo- Contrarywise, Thorne and Allen (1959)observed nomicvalue sbould be placed, at specific or that,in the same species, thehost induced genericlevels, tothis character. However, the “markedvariations” in length of theP.U.S. oocyteswere never arranged in several rows, Kheiri (1972) found variations to occur in the andthis disposition never appears in Ditylen- length of the P.U.S. of D. destructor. Evans and chus spp.Three genera in Anguininae have Fisher (1970) showed the length of the P.U.S. oocytes in several rows (l) : Anguina, Nothan- to beindependent of the food supplyin D. guina and Afrina (Brzeslri, 1981). nzyceliophagus. In view of theseconflicting observations, it isbest not to use the actual length of theP.U.S. for speciesidentification. Ratios relating this length to other dimensions

(l) Therachis described by Thorne (1949) for Anguina tritici was believed by Nagamine andMaggen- ti (1980) to be an oocyte surrounded by the epithelium (z) See Fortuner, Merny and Roux (1980) for dis- of the oviduct. cussion on the name “columella”.

Revue Nématol. 5 (1) : 17-38 (1982) 25 R. Fortuner

such as vulval diameter or vulva-anus distance . Taxonomic cha.racters in males sometimes have no mathematical meaning and Table 2 presentssome measurements for mustbe used with caution. However, the males in the present populations. The demanian P.U.S. length can be used in a very broad sense for separating species withshort P.U.S. from ratios were also studied. The ratios a, b, and c. thosewith long P.U.S. The P.U.S. illustrated have constituent measurements significantlyc.or- relatedbut the regression lines do not pass for D. destructor either in Goodey (1952) or in Kheiri (1972) are rather long structures, reach- throughthe origin. These ratios must not be used. ing far from the vulva level. D. myceliophagus also has a longP.U.S. Both species canbe Spicules. Thespicule lengt,h is a reasonably separated from others with short P.U.S. as for constantcharacter in the present. specimens example D. trifornzis. (Tab.2) and this character can be used for The absence of any P.U.S. in some species in species identification. Ditylenchus will be discussedbelow. Inthe The spicules were ventrally arcuate, with an presentspecimens, the P.U.S. was eitheran anterior head slightlyoffset (i.e. slightly “cepha- empty,flattened structure (Fig. 2 L), or. a lated”). Thishead was about twice as long as broadsac, filled with a. granularsubstanc.e wide (i.e. “anteriorly expanded”) (Fig. 2 N, O). (Fig. 2 M). This substance may be degenerating The shape of the spicules was used by Siddiqi spermcells’ which had entered this dead end (1980a.) to assignhis new genus Safianema to after the spermatheca was filled. It couldalso Anguininae. Safianema wassaid to be close be a degenerating egg. An egg wasseen in a to Ditylenchrrs in, among other characters, the specimen of D. myceliophagus from France, half- structure of the spicules“ventrally arcuate, way engaged into the P.U.S. anteriorly expanded’’: Inthe same article, Siddiqi redefined Pseudhalenchus Tarjan, 1958 ’ Vulva. Thedistance from head tovulva is and placed this genus under Tylenchidae. The very strongly correlated wit.h the body length spicules in Pseudhalenchus (sensu Siddiqi, 1980~) (Fig. 1) and the regression line passes very near are “slender, arcuate, cephalated but not promi- the origin. A similar result was obtained for D. nently expanded anteriorly”. destructor by Wu (1960b).The coefficient V is Theshape of the spiculesseems variable mathematically correct. It is also very efficient among species of Ditylenchus. D. angustus, as. in reducing the variability of its morphomet,ric figured by Seshadriand Dasgupta (1975) has constituents : its coefficient of variabilityis spicules strongly cephalated but not expanded only about 2% compared with C.V.s of 20 to anteriorly.Contrarywise, the spicules of D. 25% for bodylength and headto vulva distance. dipsaci and D. destrucfor (in Thorne, 1945) are Goodey (1952) remarked that, in D. destructor, notcephalated but markedly expanded ante- “the relative position of the vulva, which is a riorly. D. equalis, as described by Heyns (1964) structural feature, is however, practically unaf- has spicules not cephalated and not expanded. fected [by the host]”. In view of this variability this character should Whilethe coeffic,ient can be usedwith con- not be used for taxonomic purposes. fidence for specifit. identification, unfortunately Bursa. The bursa length (measured from the most of the descrihedspecies in Ditylenchrrs level of anus to the posterior end of the bursa) sharesimilar values for this character : about isvery variable (Tab. 2). Thislength is not 80%. correlated to the tail length (r = 0.1780 with The vulval lips are slightly elevated or not 26 d.f.).Bursa in Ditylenchus isalways lepto- at al1 (Fig. 2 L, M). The vulval slit is oriented deran. This character was used by Meyl (1961) at astraight angle from the body axis. Some to differentiate Neoditylenchus, a newgenus, species in Ditylenchus havevulva slits more withbursa peloderan, frorn Ditylenchus. (D. obliquely oriented (D.angustus for example) but zrirtudesae has a bursa reaching ta tail tip but infact this character was notdescribed for not enveloping it, so it is not a true peloderan most species in Ditylenchus and cannot be used bursa). Filipjev (1936b)described the bursa of for the moment in . Difylenchus has “bis Oder fast bis zur Schwanz- -~ . - - - . - - -. - .- .- -. ~ - -__ ~ . - 26 Revue Némafol. 5 (1) : 17-38 (1982) Genus Ditylenchus

1 . Table 2 Ditylenchus myceliophagus : Quantitative measurements of individuals from three origins Males (measures in Pm) : Mean f confidence interval ; range ; coefficient of variability.

C riteria Sample Criteria 1 Salnple 2 Sample 4

(n = 20) (Il = 8) , - (n = 5)

Length 664 f 26 (568-792),8.9% 734 f 50(636-846), 9.8% 646 f 17 (614-664) Stylet 7.1 f 0.1 (6.5-8)4.3% 7.3 f 0.2 (7-7.5),3.5% 7.0 Hemizonid 82 f 3 (72-97),7.6% 83 f 4 (77-89), 6.6% 81 f 3 (75-85) Escre. pore 85 f 3 (76-101),7.2% 87 f 3 (82-93), 5.7% 84 f 3 (78-88) Oes. (valve) 11G f 4 (100-133), 8.0% 116 f8 (103-130), 9.7% 123 f 8 (111-133) Oes. (gland) 123 f 3 (108-136),5.7% 130 f 4 (119-138), 4.9% - 127 & 8 (116-136) Tai1 49 f 2 (43-60),10.3% , 51 & 2 (47-56),6.9% 62 f 4 (57-68) Bursa 25 f 2 (17-33),18.7% 27 f 2 (22-30),12.1% 42 f 4 (36-46) Body diameter 16 f 0.7 (13.5-18),9.5% 18 f 1 (15-20),10.3% 22 f 1 (19.5-24) Testis 321 f 31(192-434), 22.0% 412 f 47 (321-517), 16.6% 244 f 43 (182-304) l Spicules 19.2 f 0.5 (17-21), 6.2% 20.1 f 0.8 (19-22), 5.6% 20 f 0.9 (19-21) Gubernaculum 5.8 f 0.2 (5-7), 9.4% 7.1 f 0.3 (6.5-8), 6.2% 7.5

spitzereichend” [Transl. : “Reaching to, or struciurewas described byWu (1967a) as almost to, thetail tip”]. Thorne (1949) dis- typical of Ditylenckus whereas Tylenchus s.1. tinguished Tylenclzus s.1. with“bursa short, had small spermcells without prominent vesicle. adanal” from Ditylenclzus with “bursa envelop- ing one-fourth of tail or more”. Andrassy (1976) separatedAnguinidae with “bursa relatively The genus Ditylenchus Filipjev, 1936 (3) large,reaching to 2/3 of taillength or more’’ from Tylenchidae and Psilenchinae with “bursa short, adanal, not reaching to1/2 of tail 1engl.h”. DEFINITION(emended) Originaldescriptions of 25species of Dity- lenchus ‘were studied. For eight of these .species, Anguininae. Lipsusually with no obvious the bursa reach to about 113 of the tail lengt,h, striations,faint annulations visible in some theshortest being thebursa in D. solani species.Cephalic frameworksclerotized. Spear “enveloping slightly less than 1/5 of tail length” with basal knobs, its protractormuscles attached (Husain & Khan, 1976). 1 think it is misleading to basal plate of the frameworlc. Four or more not to cal1 adanal a bursa reaching only to 1/5 lines in the lateral field. Median bulb fusiform, or 1/3 of thetail length. It maybe that in withrefractive thickenings. Isthmus not sep- some Tylenchinae with filiform tails the relative arated€rom glandular bulb by a conslriction. length of Ihebursa is evenshorter, but this Basalglandular bulb arranged symmetrically character should be further studied before being aroundthe intestine, with glands either of used in classification and ihen a different termi- nologymust be used.For identification of species of Ditylenchus it is possible to separate (3) Ditylenchus in Filipjev, 1934 is a nomen nudum (Goodey,1963). A more complete description of the species with short and long bursae but, as said genuswas given by Filipjev in two articles (1936a above, the ratio bursa length/tail length must and 1936b). Loof and Oostenbrinlc (1958) stated that not be used. Filipjev (1936a) was published on July 22, 1936 and Filipjev(1936b) also inJuly 1936, at anunknown Sperrn cells. Inthe present specimens, the date.Actually, the letter of Dr. Sveshnikovafrom sperm cells, either in the receptaculum seminalis which was obtained the information about the second of males (Fig. 2 N, O) or in the spermathecae article was mistranslated. The correct datefor Filipjev, of females (Fig. 2 M) were composed of a dark 1936b isOctober, 1936 (Loof,pers. comm.). Filipjev 1936a is the correct reference for the original descrip- nucleus, 2 pm in diameter enclosed in a trans- tion of Ditylenchus and also for Pratylenchus, Roty- lucent vesicle 5-6 pm indiameter. Such a lenchus and Tetylenchus.

Revue Nérnatol. 5 (1) : 17-38 (1982) 27 R. Portuner

equal length or with one gland longer, overlap- D. indicus(Sethi & Swarup, 1967) comb. nov. pingthe intestine for a very variable length. syn. Pseudhalenchusindicus Sethi & Swarup, 1967 Anteriorovary straight or with one or two D. inobservabilis (Kirjanova, 1938) Kirjanova, flexures,with oocytes in one or two rows. 1961 Spermatheca in linewith the genital tract, D. istatae Samibaeva, 1966 generallya tubular elongated structure. Colu- D. khaninom. nov. syn. Diptenchus indicus Khan, Chawla & Ses- mellawith four rows of four cells, no longer hadri, 1969 than spermatheca. Post uterine sac present or D. lutonensis (Siddiqi, 1980) comb. nov. absent. Male withbursa of variablelength syn. Safianema lutonense Siddiqi, 1980 but never enveloping the tail end. D. medicaginis Wasilewska, 1965 D. melongena Bhatnagar & Kadyan, 1969 Ditylenchus isdistinctive among Anguininae D. microdens Thorne & Malek, 1968 in having oocytes in one or two rows, median D. nzinutus Husain & Khan, 1967 bulb with refractive thickenings and columella D. mirusSiddiqi, 1963 with four rows of four cells. D. nzyceliophagus Goodey, 1958 syn. D. geraerti (Paramonov, 1970) Bello & Geraert, 1972, n. syn. D.nanus Siddiqi, 1963 & LIST OF SPECIES OF Ditylenclzus D. nortoni (Elmiligy, 1971) Bello Geraert, 1972 syn. Basiroides nortoni Elmiligy, 1971 nec Basiroides nortoni (Thorne & Malek, The reader may refer to the book of Tarjan 1968)Fotedar & Mahajan, 1973, syn. andHopper (1974) for the taxonomic avat,ars Basiria nortoni Thorne & Malek, 1968. D. obesus Thorne & Malek, 1968 and list of synonyms of the cited species through D. sibiricusGerman, 1969 1971. D. solani Husain & Khan, 1976 D. sonchophila Kirjanova, 1958 (citedin Para- monov, 1970) Valid species D. taleolus (Kirjanova, 1938) Kirjanova, 1961 D. tausaghyzatus (Kirjanova, 1938) Kirjanova, Type species 1961 D. tenuidensGritsenko, 1971 Ditylenchusdipsaci (Kühn,1857) Filipjev, 1936. D. triformisHirschmann & Sasser, 1955 Other species : D. valveus Thorne & Malek, 1968 D. acutus (Khan & Nanjappa, 1972) comb. nov. D. virtudesae Tobar Jimenez, 1964 syn. Pseudhalenchus acutus Khan & Nanjappa, 1972 Species of fhe genus Ditylenchus considered as D. anchilisposomus (Tarjan, 1958) comb. nov. imperfectly described (species inquirendae) seven syn. Pseudhalenchusanchilisposmus Tarjan, 1958 species.(4) : Sapanema anchilisposomum (Tarjan, 1958) By Meyl (1961) : Siddiqi, 1980 D. darbouxi (Cotke, 1912) Filipjev, 1936 D. angustus (Butler, 1913) Filipjev, 1936 D.sycobius (Cotte, 1920) Filipjev, 1936 D. ausa@Husain & Khan, 1967 By Goodey (1963) : D. brassicae Husain & Khan, 1976 D. caudatus Thorne & Malek, 1968 D. breuicauda (Micoletzky,1925) Filipjev, D. clarus Thorne & Malek, 1968 1936 D. convallariae Sturhan & Friedman, 1965 D. cyperi Husain & Khan, 1967 D. damnatus (Massey, 1966)comb. nov. syn. Pseudhalenchus damnatus Massey, 1966 Safianemadamnatum (Massey, 1966) Sid- diqi, 1980 D. deiridus Thorne & Malek, 1968 (4) ChiEinotylenchusboevii Izatullaeva, 1967, Anguillu- D. destructor Thorne, 1945 lina incognata Van der Linde, 1938, C. sedatus Kirja- D. dipsaci falcariae Poghossian, 1967 nova, 1951 and Tylopharynx annulatus Cassidy, 1930 D. dipsacoideus (Andrhssy, 1952) Andrissy, 1956 are listed in Tarjan and Hopper (1974) under Dity- D. drepanocercus, Goodey, 1953 Zenchus. In fact, Sher (1970) considered these species D. emus Khan, Chawla, & Prasad, 1969 as species inquirendae under the nameChitinotylenchus. D.equalis Heyns, 1964 Thelast one was transferred by Golden (1971) to .- .~ . . -- D.-galeopsidis Teploukhova. 1969 .. __ - , -- Tylenqhorhynchus. ------28 Revue Nématol. 5 (1) : 17-38 (1982) Genus Ditylenchus

To this group of imperfectly described species, D. striatus (Fuchs, 1918) Rühm, 1954 it seems necessary to add the following : By Goodey (1963) : , D. bacillifer (Micoletzky,1922) Filipjev, D. pinopldus (Thorne, 1935) Filipjev, 1936 1936 D. Parus Meyl, 1954 D. humuli Skarbilovich, 1972 - To Anguina (two species) D.intermedius (De Man,1880) Filipjev, By Filipjev (1936a) : 1936 D.bnlsamoplzilus (Thorne, 1926) Filipjev & D. karalcalpakensis Erzhanova, 1964 Scbuurmans Stelthoven, 1941 By Thorne (1961) : Species considered of doubtful position (species D.amsinckiae Filipjev & Schuurmans Stelt- inc,ertae sedis), eight species (5) : hoven, 1941 By Paramonov (1970) : - To Orrina (one species) D. beljaevae Karimova, 1957 By Brzeslti (1981) : D. eurycephalus (DeMan, 1921) Filipjev, D. phyllobius (Thorne, 1934) Filipjev, 1936 1936 - To Subanguina (fourspecies) D. procerus (Bally & Reydon, 1931) Filipjev, By Paramonov (1967) : 1936 D. radicicola (Greef, 1872) Filipjev, 1936 D. pumilus Karimova, 1957 By Brzeski (1981) : D. sapari Atakbanov, 1958 D.askenasyi (Bütschli, 1873) Goodey, 1951 D.tulaganoui Karimova, 1957 D.brenani (Goodey,1945) Goodey, 1951 By Brzeski (1981) : D.graminophilus (Goodey,1933) Filipjev, D.pustulicola (Thorne, 1934)Filipjev & 1936 SchuurmansStelthoven, 1941 - To Deladenus (two species) To this group of species of doubtful position By Goodey and Franklin (in Goodey, 1956) : is now added : D. arboricolus (Cobb,1922) Filipjev Le, D.paragracilis (Micoletzky,1922) Sher, Schuurmans Stekhoven, 1941 1970 By Thorne (1941) : Species of Ditylenchus later transfered to other D. durus (Cobb, 1922) Filipjev, 1936 genera . - To Tylenchus one species - To Neoditylenchus (fourteenspecies) By Bello and Geraert (1972) : By Meyl (1961) : D. misellus Andrassy, 1958 D. abieticolus, Rühm, 1956 D. autographi Riihm, 1956 D.dendrophilus (Marcinowski,1909) Fi- RELATEDAND SYNONYM GENERA ' lipjev & SchuurmansStelthoven, 1941 D. eremus Rühm, 1956 D. gallicus (Steiner, 1935) Filipjev, 1956 The genus Chitinotylenchus

D. glisclzrus Rühm, 1956 ' Chitinotylenchusparagracilis (Micoletzky, D. major (Fuchs, 1915) Filipjev, 1936 1922)Filipjev, 1936was redescribed bySher D. ortus (Fuchs,1938) Filipjev & Schuur- (1970)from the onlyknown specimen, the mans Stekhoven, 1941 female holotype. Sher transferred C. paru.gracilis D. panurgus Rühm, 1956 to Ditylenchus andproposed to consider Chiti- D.petithi (Fuchs, 1938) Rühm, 1956 notylenclzus Micoletzky,1922 and Ditylenchus D. pityokteinopldus Riihm, 1956 Filipjev, 1936 assynonyms. To preservethe wellknown name Ditylenclzus, Loof and Sher (1971)reyuested from the International Com- mission of Zoological Nomenclature to supress the name Chitinotylenchus and to place Ditylen- (6) Tylenchuscafeicola Schuurmans Steclrhoven, chus on the Officia1 List of GenericNames in 1951 was believed by Goodey (1963)to be a Ditylenchus but too meagerly described to be attributed to this Zoology. Dr. Lemche latter suggested to also genus with confidence. place the name Chitinotylenchus on the OfTicial

Revue Nématol. 5 (1) : 17-38 (1982) 29 R. Portuner

Index of Rejected and InvalidNames in Zoology Anotherdif€erentiating character waspro- and Dr. Loof gave a list of references with the posed by Brzeski(1981) : the vagina wassald name Difylenchus to implement his earlier to beoblique to the body axis in Dipfenchus, proposa1 (Lemche ; Loof, 1974). perpendicular to bodyaxis in Ditylenchus. In In June 1975, the Commission supported the fact the orientationof the vulva is notdescribed application by nineteen votes ta one. Dr. Dupuis or figuredfor most speciesin Ditylenchus. In voted for postponing the decisionbecause the thepresent specimens the vulva was mostly synonymization of thetwo genera was the perpendicular but sometimesmade a slight opinion of a single scientist.Three specialists angle with the body axis. A wider angle can be were c.onsulted. Luc accepted the conclusion of seen in illustrations of D. caudatus, D. deiridus Sher while Andrassy and Siddiqi questioned it and D. ualveus (Thorne & Malek, 1968), D. (Siddiqi(1971) had accepted the synonymiza- angusfus ' (Filipjev & SchuurmansStekhoven, tion in an earlier article) because some generic 1941 ; Seshadri & Dasgupta,1975) and D. characters are not visible in the flattened and norfoni (Bello & Geraert, 1972). The use of this clearedfemale holotype and the maleis not character is questionable at generic level. known for C. paragracilis (Melville, 1977). The The pyriform bulb illustrated for Dipfenchus commission was then asked to choose whether indicus (Khan, 1969)is not differentfrom the to suppress Chitinotylenchus as originally decided correspondingstructure in Ditylenchus clarus or to give Ditylenchus precedence over Chitino- (with a long P.U.S.),D. emus (P.U.S. of medium tylenchus whenever the twonames are con- length), D. nortoni and D. obesus (P.U.S. about sideredsynonyms. Thismeans that whoever onebody diameter long). The first character considers the two genera as two different valid used in the original diagnosisof Dipfenchus does taxa would be entitled to use both names but not differentiate this genus from Ditylenchus. when they are held to apply to the name genus, Al1 species in Difylenchus have a P.U.S. except Difylenchus is thename to be used.The final Difylenchusdeiridus. This speciesalso has a decision of the Commissionis expectedto be pyriform glandular bulb resembling Diptenchus published soon (Melville, pers. comm.). indicus. However, the recognition of Diptenchus 1 consider that becausesome important as a valid genus and the transfer of Difylenchus features relevant, at generic level are not known deiridus to Diptenchus is not advocated here for for Chitinofylenchusparagracilis (namelyar- the following reasons : rangement of oocytes in the ovary and structure - Diptenchus differs from Difylenchus in one and size of spermatheca, columella, male bursae character only. Al1 other features are remarlmbly and sperm cells), it is not possible to consider sinlilar in males and females of species of these it as a species of Difylenchus, neitheris it two genera. possible to assign Chifinotylenchus a place among - Presence or absence of P.U.S. is a charac- other genera in the Anguininae.Following the ter useful for specific identification (see Tab. 3). opinion of Andrassy(in Melville, 1977), 1 Identificationis different from taxonomy and regard Chitinotylenchus a genus inquirendurn the erection of a newgenus for identification and C. paragracilis a species inquirenda. purposes is unwarranted and unnecessary. - The post uterine sac represents the relict The genus Diptenchus of a posterior genital branch. The modern forms Dipfenchus was proposed to acc,omodate Dip- of nematodes possessing this structure probably fenchrrs indicus Khan, Chawla & Seshadri, 1969, evolvecl from ancestral forms with two genital typeand so faronly species inthe genus. branchesequally developed (in somegenera, Diptenchzrs was differentiated from Difylenchrrs modernspecies presentdifferent States of the by : i)the shape of the glandular bulb (pyriform, regression of the posterior branch : for example, set off from the intestine in Dipfenchus, clavate many Helicotylenchus have two equal branches, to variouslyexpanded, sometimes lobed in H. mulficinctus has a shorter posterior branch, ,Difylenchus); ii) the absence of a post uterine H. neoformis and Rotylenchoidesintermedius sac(P.U.S. present in Ditylenchus) (Khan havevestigial posterior branches and typical Chawla & Seshadri,, 1969). .-species in Rofylenchoides- possess. short P.U.S.). ._.-- .. ------. - 30 Revue NPmafol. 5 (1) : 17-38 (1988) Genus Ditylenchus

No modernform exists resembling the hypo- questioned by Geraert and Kheiri (1970). These thetical ancestral form of Difylenclzus with two authors concluded that “the differences between genital branches. Inthat genus, the P.U.S. varies P. anchilisposonzus and D. desfrucfor are appar- from a long structure to a short sac or disap- rentlyonly quantitative (...) so this species pearscompletely (see Tab. 3). Grouping in a could probablybe transferred to thegenus separategenus the forms completely lacking Difylenchus”. this structure would put an unnecessary empha- The narrowness of the intestine at the level sisupon what is onlythe logic end of the of the oesophagealglands is most probably a regression. consequence of the very presence of the glandu- - Species withno or very reduced P.U.S. lar lobe and the necessity to make room for this are present in the related genus Subanguina : structure.A similarly narrow intestine was S. moxae, S. calamagrosfis, S. granzinophila, S. observed in the specimens of D. myceliophagus millefolii, while other Subanguina species have with a long oesophageal lobe (Fig. 2, D). There long P.U.S.To be consistent with the diagnosis is no difference in structure between narrower of Dipfenclzus, a new genuswould have to be orlarger intestines and this character has no providedfor these species.Species without value for generic differentiation. P.U.S. exist perhaps in other genera -in Angui- Observations of D. myceliophagus from the ninae (1 haveobserved a Noflzofylenclzus sp. IvoryCoast, as explained above, have shown withoutP.U.S.). The creation of new’genera that the lengthof the oesophageal overlap varies basedon this character, and the acceptance greatly during the life of any particular individ- of Dipfenchus, wouldconfuse the relationships ual. Young West African specimens are remark- existingbetween the genera in Anguininae ablysimilar tothe description of Safianelna because emphasizing a regressed structure (Mayr while older individuals fit well into the diagnosis 1969,cautions against using regressed organs of Ditylenclzus. . for classification purposes). Could it betlzat this similarity was only Diptenclzus Khan, Chawla & Seshadri,1969 apparent and that it was nevertheless possible is here proposed as a junior synonynl of Dify- to differentiate Su.fianema, withglands lying lenchrrs Filipjev, 1936. Dipfenchus indicus Khan. free over the intestine, from Difylenclzus, with Chawla & Seshadri,1969 is transferred to the glandsenclosed in a basalbulb ? Theultra- genus Difylenchus. As thename Difylenclzus structure of the glandular region of the oesoph- indicus ispreoccupied by a speciesdescribed agus of D. myceliophagus could not be studied earlier (Pseudhalenclzus indicus Sethi & Swarup, for material reasons, but’interesting conclusions 1967, transferred to Difylenchus in the present can be drawn from two studies published, the article), a new name is here proposed Dipfen-for first onD. dipsaci (Yuen, 1968)which is supposed chus indicus : Difylenchus kkani nom. nov. to have “aclavate posterior oesophageal bulb that butts ont0 or slightly overlaps the intes- The genus Safianema tine” (Hooper, 1972), and the second on Netero- Siddiqi(1980a) proposed Safianema n. gen. deraglycines (Baldwin, Hirschmann & Trianta- to accommodate a new species, S. lutonense and phyllou, 1977) which, likeal1 Heterodera species, those species in Pseudhalenchus Tarjan,1958 has glands lying free over the intestine. which show close afinities with the Anguininae Yuen (1968)described thepostcorpus of D. (through similarities in lip region, spear, gonads, dipsaci as a “thinwalled elastic sac” containing spiculesand absence of acardia). The new theglands. At the anterior end the Wall is genus was differentiated from Ditylerzchus by : thicker, containing large poclrets of nuclei and i) the oesophagealglands extending as an mitocbondria (Fig. 16 of Yuen, 1968). In middle elongatedlobe over the intestine and ii) the portionthe Wall isreduced tothe “basement intestinenarrower at level of theoesophageal membrane” (Fig. 17 of Yuen, 1968). glands. In Heferodera glycines, Baldwin, Hirschmann The taxonomic position of one of the species & Triantaphyllou (1977) described at the ante- transferredby Siddiqi to his newgenus, P. riorend of the oesophageallobe, peripheral anchilisposomus ( = S. anchilisposomurn.) was nucleiassociated with narrow bands of tissue

Revue Nématol. 5 (1) : 17-38 (1982) 31 R. Fortuner

of the oesophagus. Fig. 23 of Baldwin,, Hirsch- anchilisposomtrs identified inJapan by Dr. mann & Triantaphyllou (1977) is quite similar Yamamoto was also examined and its iclentity to Fig. 16 of Yuen(1968). More posteriorly, as D. anchilisposomus was confirmed. the gland lobe is sheathed by the basal lamina Paratypes of S. damnatum also presented (= basementmembrane of Yuen)only, and every charac.teristic of Ditylenchzrs. The genital Fig. 26 of Baldwin, Hirschmann & Triantaphyl- branch has the typical structure of Ditylenchus, lou (1977) resembles Fig. 17 of Yuen (1965). (columella,spermatheca, ovary). Stylet iength From these two studies, no difference appears in female (not indicated in original description) to exist in the structure of the glandular part was 12.pm, lateralincisures were not absent as of the oesophagus in D. dipsaci and in a species mentioned, but very diEcult to observe, Three describedwith glands free, overlapping the lines were seen on tail. The number of lines on intestine. It isprobably that in Ditylenchrrs thebody could not bedetermined. The tail there exists no such structureas a “basal bulb” : wasmore pointed t,han originally described. in somespecies of thisgenus the oesophageal This species is here transferred to Ditylenchzrs as glands\stop short of the oesophago-intestinal D. damnatus (Massey,1966) comb. nou. junction, while in others they extend posterior Paratypes of S. hylobii proved this species to to it. bequite ,different from the preceeding ones, Because there appears to be no structural dif- withprotractor muscles of styletattached to ferences inthe glandular oesophageal lobe in cephaliccuticle, spernlatheca oblong, as a Ditylenchus and Safianema, andbecause i.his diverticulum offsetfrom uterus,packed with structure was observed to vary during the life small rounded sperms lacking translucent ves- of individual specimens, it isconsidered to be icle, crustaformeriawith cells irregularly dis- unfit for diagnostic purposes. Safianema Siddiqi, posed, tail filiform and male bursa very small. 1980 is here proposed as a junior synonym of Thestructure of the femalegonad andmale Ditylenchus Filipjev, 1936. Four specieswere sperm cells fit the definition of Pseudhalenchus included inthe genus Sa.fianema by Siddiqi (sensu Siddiqi, 1980) better, andit is transferred (1980) : back to this genus. S. lutonense Siddiqi, 1980, type spec.ies Siddiqi (1980~)proposed to leave P. indicus S. mchilisposomum (Tarjan,1958) Siddiqi, and P. actrtus inthe genus Pseudhalenchus, 1980 which he redefined as a member of Tylenchinae syn. Pseudhalenchusanchilisposomus Tar- (seediscussion below). Female paratypes of jan, 1958 both species were examined and were found to S. damnatum (Masseg, 1966) Siddiqi, 1980 have every characteristic of the genus Ditylen- syn. P. damnatus Massey, 1966 chus as redefined here. Male paratypescould S. hylobii (Massey, 1967) Siddiqi, 1980 not be obtained, but sperm cells present in the syn. P. hylobii Massey, 1967 spermathecae of al1 the female specimens were S. lutonense fits well the diagnosis of Difylen- of the Anguininae-type. chr~sas givenabove. The oesophageal overlap Pseudhalenchusindicus and P. aczrfus are is45 to 59 Fm long, of thesame magnitude here transferred to the genus Ditylenchus under that the corresponding structure in sonle of the the names Ditylenchus indicus (Sethi & Swarup, presentspecimens. Paratypes were examined. 1967) comb. nov. and Ditylenchus acutus (Khan Structure of oesophagusand intestine showed & Nanjappa, 1972) comb. nov. no difference with Ditylenchus. Thenew c.om- Paratypes of D. indicus have a shorter stylet bination Ditylenchuslutonensis (Siddiqi,1980) (8 km) and a more rounded tail than originally comb. nov. is here proposed. described (Sethi & Swarup, 1967). Examination of paratypes of S. anchilisposo- mum support, the opinion of Geraert and Kheiri The genus Pseudhalenchus (1970)and this species is here transferred to Pseudhalenchus Tarjan,1958, was redefined Ditylenchus as D. anchilisposomus (Tarjan, by Siddiqi (1980) to include the species which, 1958) comb. nov. It differsfrom D. desfrucfor bec*ause of thestructure of male and female

- ~-in. sever_al~-_cha;raGters-as seen_---- in Table~ -. .- -~3. P. -gonads, -- are relatedto Tylenc.hinae. - - - -_-_ - 32 Revue Nématol. 5 (1) : 17-38 (1982) Genus Ditylenchus

Paratypes of P. rninutrts Tarjan,1958, the geraerti issmaller (400-455 Pm) than D. myce- type species, were young females withinconspi- liophagus (600-1 380 Pm), but body length was cuous spermathecae. As far as could be observed, proven to be dependent on food supply (Evans this structure was axial, but certainly smaller & Fisher, 1970). Some West African individuals than in most Ditylenchus spp. No sperm cells of D. rnyceliophagus (sample 3 andspecimens wereobserved inthe sperrnathecae of the from Taï forest) were also very small (less than felnales but two male paratypes had sperm cells 600 Pm), whereasother West African popula- small and without translucent vesicle. tions (samples 1, 2 and 4) were of the same size The structure of the sperm cells,which is a as typical D. rnyceliophagus (600-1380 pm in very significant character, oblige to assign P. Hesling, 1974).No males were found and sperma- nzinutus to Tylenchinae. As pointedout by thecae of D. geraerli are empty. However, if we Siddiyi(1980) it is unique among Tylenchinae suppose that the three individuals observed by in having elongated gland lobe.No intermediate Geraert(1962) were young, immature females, formexists between typical genera in Tylen- this could explain their small size, short ovary, chinaewith small “bulb” and P. nzinutus. and absence of sperms in spermathecae. Exami- Consequently, Pseudhalelzchus appears tobe nation of a paralectotype of D. geraerti failed distinct from al1 genera in Tylenchindae and is to show any difference with West African speci- considered a valid genus. mens and with description of D.mycelioplzagus. It does not seem necessary toassign Pseudha- Therefore, D. geraerti is synonynlized with the lelzclzus to a separatesub-family because it latter species. presentsonly quantitative and not structural D. plzloxidis, listed as synonym of D.dipsaci difference with other genera in Tylenchinae (see in Tarjan and Hopper (1974), actually presents discussionabove on thenature of the“basal geneticincompatibility with some populations bulb”).The sub-family Pseudhalenchinae Sid- of that species and the suggestionwas made that diqi,1971 (6) isconsidered synonym of Tylen- it was in~astate of active speciation (Ladygina, chinae Oerley, 1880. 1974). Another species is excluded from Tarjan As saidabove, P. lzylobii Massey,1967 is a and Hopper’s list of synonyms of D. dipsaci : valïd species of the genus Pseudhalenchus sensu D. destructor is not considered synonymous with Siddiqi (1980). D. dipsaci because of greaternumber (six) of lines in lateral field (Thorne, 1961).

ON THE STATUS OF SOME SPECIES OF Ditylelzcllus Inzperfecily described species Thorne (1961)expressed thegravest doubts . Synonynz species about the identityof D. intermedius : “Actually, The validity of some species is doubtful. For this name appearsto have been used as a dump- example, D. sonchophila, and D. dipsacifalca- ing ground to ‘accommodate a number of elosely riae are lnorphologically veryclose to D. dipsaci rela!ed forms”. Loof (1961) studying the nema- and are probable synonyms of this species. tode collection of De Man found only one male. No significantdifference could be found (Ano-lher specimen of D. intermedius, a female, between D. gera.erti and D. myceliophagus. D. was lostduring remounting). He’could not determinethe exact length of thebursa, and the tail was much longer and slenderer than the original description. The number of Iines in the lateraI field was

(G) Siddiqimentioncd the new subfamily atthe not indicated in these two works nor in Para- E.S.N. symposium at Pescara in September 1970. This monov (1970) or in Goodey (1932). The valueof does notconstitute a publication(Art. 9 (4)O€ the V was given as 70% by Thorne (1961), 76432% Code of Zoological Nomenclature).In the published byParamonov .(1970) and 68.5-82.5% by abstracts (Siddiqi, 1970), the name Pseudhalenchinae isnot accompanied by a statement giving the cha- Goodey(1932). Because so manydiagnostic racters differentiating the new taxon.The dispositions characters are unltnown, it seems best to con- of Art. 13 (a) of the Code are not fulfilled. sider D. irzterrnedius a species inquirenda.

Revue Nématol. 5 (1) : 17-38 (1982) 33 R. Portuner

Table 3 Tabular Key to Species of Ditylenchus

Groups StyletGroups Tai1 Lateral P. US. V% Bursa Spicule Species length Pointed . lines Short 1 Short length 1 : -+9 Pm Rounded 4 Long -+7Qy0 Long 1 2: 10 ym-f Broad 6 O: no 2 +-12 ym Sickle (=more P.U.S. +YY% 2 than 4) 3 +-16 ym 484 y. 3 4 -21 ynz 4

1 1 P 4 O 4 - - D. deiridus s 3 S 2 D. sibiricus S 3 S 2 D. equalis S 3 L (3 ?) D. microdens s-L 3 S 4 D. nortoni 2 1 P ,6 O 3-4 L 4 D.khani S 3 L 2 D.tenuidens 113 1 4 L 2-3 ? 1 D. minutus S 2 - - D. brassicae 1 P-R 4 S 3 - D. acutus 1 P-R 6 L 2. S 2-3 D. lutonensis L 2-3 s-L 2-3 D. medicaginis 3 1 R 4 S 1 S 2-3 D. emus S 3 S 2 D. indicus 1 R ? L 2-3 L 2-3 D. dipsacoideus L 3-4 L 2, D. nanus 4 1 R 6 S 2-3 s-L 2 D. triformis L 3-(4 ?) L 3 D. myceliophagus A 1 B L 3-4 L 3 D. mirus 1 B L 3 L 1 D. virtudesae 1 S S 2-3 L 1 D. drepanocercus 317 1-2 R L 3 S 3 D. solani 41s 1-2 R L 3 L 3 D. anchilisposomus 5 2 P S 2 S 2 D. ausaji L 2-3 L 3 D. angustus L 3 L 4 D. dipsaci L 3 L 4 D. dipsaci falcariae L 3-4 L 4 D. sonchophila 5 16 2 P 4-6 L 3 - 4 D. galeopsidis 6 2 P 6 L 2-3 L 4 D. convallariae 6 18 2 P-R 6 S 3 S - D. valveus ? L 2-3 L 2-3 D. cyperi

61718 2. P-R ? S 2 L D. damnatus 7 18 2 R ? s-L 3 - D. obesus L 3 - D. clarus S R 6 S 2 S 4? D. caudatus L 3 L - D. destructor

-. -. ~ Note : D. inobseryabilis, D. istatae, D. melongena, D-. taleolus and D. tausaghyzatus are not included.in this 1rey.-

34 Revue Nématol. 5 (1) : 17-38 (2982) Genus Ditylenchus

D. bacillifer wasdescribed by Micoletzky a given species)or useless (appearing in identical (1922)as Tylenchusbacillifer fromsinglea state in al1 species of the genus). female.Some important features were not Only a few characters could be retained and mentioned(number of incisures),the stylet were used in Table 3. length of 18 pm was probablyover-estimated The first three characters (stylet length, tail (in the same paper, Micoletzky described Tylen- end,and number of lines)can usually be clzus dipsaci with a 10-18 pm spear, T. paragra- determinedfor every population and without cilis with a 13 pm spear : Sher (1970) redescrib- ambiguity. They were used to define eight groups ing the latter species measured a 8 pm spear) : of species, numbered 1 to 8. Group 7 is not tail was figured pointed, but described “... mit represented. An additionalgroup (Group A) leichtabgerundeter Spitze” [Transl. : “witha includes the species withabnormal tail ends, slightlyrounded end”] ; the description of broadly rounded or sickle-shaped. Because some cephalic framework does notfit with any known characters are unknown or overlapping for some feature : “Im Innerndes Vorderendes finden sich species, some intermediate groups (1/3, 2/4 and (vermutlich 3) chitinige Stabchen (...) von kom- so on) had to be delimited. maartiger Gestalt und veranderlicher Stellung” When the group to ’which an unknown popula- [Transl. : “inside theanterior end are found tion belongs has been determined, it must be (probably 3) chitinous rods (...) in the shape of compared to al1 the species inthat group, as a comma and of a variable position”]. D. bacil- well as to the species of the adjacent interme- lifer has apparently never been found since the diate groups. For example, if an unknown popu- originaldescription and was not referred to lation is found to belong to group 4, it must be eitherinThrone (1961), Goodey (1963),or comparedto the two species ingroup 4, the Paramonov (1970). two species ingroup 214,. the twospecies in The description of D.humuli is very meager. group 314 and the species of group 418. Only some measurements (but not stylet length These cornparisons are made using the other and V-value) and relationships (with D.dipsaci four characters. Thefinal decision onthe identity and D.destructor), but no morphological descrip- of the unknown population must use the original tion and no figure, were given. description(or reliable redescriptions) of t.he Thedescription of D. karaka.lpakensis was more closely related species. more complete, but some essential information (on genital system and lines in lateral field) is missing andthe figure presentsflatteneda ACKNOWLEDGEMENTS specimen. D. pustulicola wasconsidered as Anguina 1wish to thank : M.W. Brzeski, E. Geraert, E. Khan, pustulicola by Choi and Loof (1973) and Hooper J.W. Riffle, M. Ritter, M.R. Siddiqi, A.C. Tarjan and andSouthey (1978), but these latter authors K. Yamamoto Who kindlysupplied paratypes and suggest thatthe originaldescription of the otherspecimens for thisstudy ; 1. AndrAssy, M.W. Brzeksi, A.M. French and M. Luc Who reviewed this speciesis unsound. Brzeski(1981) said that it article and/or edited the English text; and T. Bongers, may belong to Subanguina. Forthe moment, M. Gnahore-Gohi andM. Lourd for technical assistance. it seemspreferable to consider this species as species incertae sedis.

REFERENCES(7) Tabular key to species of Ditylenchus ANDRASSY, 1. (1976). Evolutionas abasis for the systematization of nematodes. London, Pitman Publ., Fromthe present observations, and from 288 p. similar studies by various authors, it is evident that most morphometrical characters cannot be (7) Thecomplete references tothe descriptions of used for identification of the species of Ditylen- new species of Ditylenchus through 1971 can be found clzus because they are unreliable (i.e. varying in in Tarjan and Hopper (1974).

Revue Nématol. 5 (1) : 17-38 (1982) 35 R. Fortuner

BALDWIN,J. G., HIRSCHMANN,H & TRIANTAPHYL- GOLDEN,A. M. (1971). Classification of the gencra and LOU, A. C. (1977). Comparativefine structure of the higher categories of the order Tylenchida (Nema-

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LOOF,P. A. A. (1961).The nematode collection of . Edited by K. 1. Sltrjabin. Translated Dr. J. G. De Man. 1. Meded. LandbHoogesch. Wage- fromRussian for the USDA andthe National ningen, 190 : 169-254. Science Foundation,Washington, by the Israel LOOF, P.A. A. & OOSTENBRINK,M. (1958). Die Iden- program for scientific translations, 1972, iv+2OO p. ditat von Tylenchus robustus De Man. Nematologica, SESHADRI,A. R. & DASGUPTA,D. R. (1975). Ditylen- 3 : 34-43. chus angustus. C.I.H. Descriptions of plant parasitic LOOF,P. A. A. & SIIER, S. A. (1971). Ditylenchus Nenzatodes, Set 5, no 64, 3 p. Filipjev, 1936 (Nematoda) : application for protec- SETHI, C. L. & SWARUP,G. (1967). Pseudhalenchus tion under the plenary powers. Z.N. (S.)1955. Bull. indicus, a new nematode species from India (Tylen- Zool. Nom, 28 : 112-113. chinae : Nematoda). Indian Phytopath., 20 : 26-28. MASSEY, C. L. (1966).The nematodes parasites and SHER,S. A. (1970). Reclassification of the genus Chiti- associates of Dendrocfonusadjunctus (Colcoptera : notylenchus (Micoletzky,1922) anda redescription Scolytidae)in New Mexico. Ann. En€. Soc. Am., of C. paragracilis (Micoletzky, 1922)(Nematoda :

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Accepté pour publication le 25 mai 1981.