A reappraisal of Tylenchina (Nemata). 7. The family Pratylenchidae Thorne, 1949(1) Michel Luc* Laboratoire des Vers, Mztse'um national d'Histoire naturelle, 61, rue de Buffon, 75005 Paris, France. SUMMARY The classification of the family Pratylenchidae is revised. The family Nacobbidae is considered as a subfamily under Praty- lenchidae and the family Radopholidae is synonymized with the second subfamily, Pratylenchinae(= Radopholinae, Hoplotylinae and Hirschmanniellinae). Genera included in Pratylenchinae are : Pratylenchus (type genus), Apratylenchoides, Hirschtnanniella, Hoplotylus, Pratylenchoides, Radopholus (= Radopholoides n. syn.) and Zygotylenchus. The subfamily Nacobbinae contains only Nacobbus. A table of characters is given which permits identification of genera. RÉSUMÉ Réévaluation des Tylenchina (Nemata). 7. La fanzille des Pratylenchidae Thorne, 1949 (Tylenchoidea) La classification de la famille des Pratylenchidaeest révisée. La famille des Nacobbidae est considérée comme une sous-famille des Pratylenchidaeet la famille des Radopholidae est synonymisée avecla seconde sous-famille, Pratylenchinae(= Radopholinae, Hoplotylinae et Hirschmanniellinae). Les genres compris dans les Pratylenchinae: PratyZenchus sont (genre type),Apratylenchoides, Hirschtnanniella,Hoplotylus, Pratylenchoides, Radopholus (= Radopholoides n.syn.) et Zygotylenchus. La sous-familledes Nacobbinae contient le seul genre Nacobbus. Il est donné une table des caractères permettant l'identification des genres. Thorne (1949) proposed the subfamily Pratylenchi- from Pratylenchidae as a doubtful genus, andHoplotylus nae, under Tylenchidae with five genera : Pratylenchus as showing more affinities with Hoplolaimidae; follow- (typegenus), Radopholus,Chitinotylenchus, Nacobbus ing Allen (1960), he suggested that Rotylenchulus may and Rotylenchulus. be removed from Pratylenchidae as having more re- Chitwood (1950), apparently not aware of Thorne's semblance to Hoplolaimidae. action, placed Pratylenchus and Radopholus in the sub- Allen and Sher (1967) did not recognize pratylenchids family Hoplolaiminae, together with other generahaving at family level, and placed this group inthree different vermiform females (Hoplolaimz, HelicotyZenchus, Roty- subfamilies under Tylenchidae; genera with vermiform lenchus,Tylenchorhynchus); he recognized othersub- females having only one genital branch (Pratylenchus, families as having saccate or globose females : Hetero- Hoplotylus) were placed in Pratylenchinae; those with derinae (Heterodera, Meloidogyne) and a new subfam- vermiform females having two genital branches (Rado- ily Nacobbinae (Nacobbus, Rotylenchulus). pholus, Pratylenchoides, Hirschmanniella and Zygotylen- Goodey (1963) considered, under Hoplolaimidae, the chus) where placed in thenew subfamily Radopholinae; subfamilies Pratylenchinae (Pratylenchus, Pratylenchoi- whereas Nacobbus alone constitutedthe subfamily des, Hoplotylus, Radopholus, Hirschmannia) and Nacob- Nacobbinae. They excluded Rotylenchulus as showing binae (Nacobbus together with Rotylenchulus). more affinities with Hoplolaiminae. Siddiqi (1963) was the first to give a clear concept of Golden (1971) accepted two subfamilies, Pratylenchi- the Pratylenchidae : he elevated Pratylenchinae to family nae and Radopholinae, as defined by Allen and Sher rank, recognized two subfamilies and pl'aced five genera (1967) and with the same generic content, under the in Pratylenchinae (Pratylenchus, Radopholus,Pratylen- family Pratylenchidae, whereas Nacobbus, because of its choides, Hirschmannia, Zygotylenchus) and one in Na- saccate female, was placed in Heteroderoidea. Nacobbi- cobbinae (Nacobbus); he also excluded Chitinotylenchus nae was elevated to family rank (Nacobbidae) withtwo (1) This article is a part of a study onthe classification of Tylenchina by the present author and R. Fortuner (CDFA, Sacramento, USA), E. Geraert (Rijksuniversiteit, Gent, Belgie), andA. R. Maggenti and D. J. Raski (University of California, Davis, USA). * Netnatologist fronz ORSTOM. Revue Nématol. IO (2) :203-218 (1987) 203 M. Luc ~ ~~ subfamilies, Nacobbinae (Nacobbus) and Rotylenchuli- authors, as eachuses various characters and various nae (Rotylenchulus). hierarchization of them to define the suprageneric taxa. The same year Siddiqi (1971) recognized three sub- These characters are : i) female vermiforme vs saccate; ., families in Pratylenchidae; he used the same subfamily ii) presence of one or two female genital branches; iii) names as Allen and Sher (1967) but with a different position of oesophageal overlap; iv) presence or absence generic content as differentiated by the position of of secondarysexual dimorphism; a) tail shapeand oesophageal overlap :i. e. Pratylenchinae, with oesopha- position of phasmids. geal overlap mainlyventral (Pratylenchus, Zygotylenchus, Only the first character cited appears as being of a Hirschmanniella) and Radopholinae, with oesophageal suprageneric level; and this is because in Nacobbus the overlap mainly dorsal (Radopholus, Radopholoides, Pra- saccate female differs from vermiform ones not only tylenchoides); the third subfamilywas Nacobbinae (Na- morpho-anatomically, but also biologically byits seden- cobbus). Hoplotylus was placed, together with Acontylus tary life with associated phenomena such as develop- in a new subfamily Hoplotylinaeunder Hoplolaimidae. ment of nurse cells in the host, eggs protected with a Andrassy (1976) in his concept of Tylenchina placed gelatinous matrix (or eggs partiallyretained in body) etc. a great emphasis on the female character, one genital Other cited characters, even though they show a corre- branch vs two, even at family level; consequently he lation, such as the position of the oesophageal overlap placed in Pratylenchidae (one branch)Hoplotylus, Praty- and secondarysexual dimorphism, do notpermit clearly lenchus and Radopholoides which, together with Aconty- separating genera into two or more groups (subfamilies lus, constituted the subfamily Pratylenchinae. Nacobbus, or even families); this is evident by the conflicting together with Nucobbodera, constituted the subfamily definitions and genericcontent offered by different Nacobbinae. The genera with two genital branches authors in these groups of pratylenchids. None of the (Apratylenchoides, Hirschmanniella, Pratylenchoides and combinations cited appear as founded, or necessary. Radopholus) together with Rotylenchoides and Rotylen- It is for this reason thathere we choose to consider the chulus were placed inthe subfamilyRadopholinae, pratylenchids as consisting of a single family, Pratylen- under Hoplolaimidae. chidae, dividedinto two subfamilies : Pratylenchinae Fotedarand Handoo (1978) produced a rather (migratory forms) and Nacobbinae (sedentary forms). confusive classification of Tylenchida as the characters used in family keys do not correspond always to those The family PRATYLENCHIDAE Thorne, 1949 given in the diagnoses; they followed Khan and Nan- = Nacobbidae Chitwood, 1950 jappa (1 972)Who elevated Radopholinae to family rank, = Radopholidae Allen & Sher, 1967 Radopholidae (Tylenchoidea), whichcontains Radopho- lus and Radopholoides; Pratylenchidae were dividedinto three subfamilies : Pratylenchinae with only Pratylen- Diagnosis chus, two new subfamilies Hirschmanniellinae (Hirsch- manniella, Pratylenchoides, Zygotylenchus and Apraty- Tylenchoidea. Marked sexual dimorphism frequent, lenchoides)and Hoplotylinae(Hoplotylus); Nacobbuswas concerning males (regression of oesophagus and stylet) placed in Heteroderoidea, Nacobboderidae, Nacobbi- or female (Nacobbinae : mature female inflated). Am- nae. phidial apertures short, slit-like. Deirids absent (except At least, Siddiqi (1986) used at the subfamily level, Prutylenchoides). Phasmids pore-like,always on tail. as a differentiel character, the presence or the absence Labial framework heavily sclerotized. of a secondarysexual dimorphism; consequently he Lip region lew, rounded or flattened anteriorly, no grouped in Radopholinae genera showing sucha dimor- longitudinal striations, not orweakly set-off from body, phism (Radopholus, Pratylenchoides, Hoplotylus,Apraty- one half to three fifthsas wide as length of spear. Spear lenchoides, Radopholoides); Pratylenchinae (Pratylen- strong; basal knobs welldeveloped, roundedor flat otylenchus) and Hirschmanniellinae (Hirsch- anteriorly (except some species of Hoplotylzu). Median manniella) were separated mainly on the bases of tail oesophageal bulb strong, rounded or oval, clearly dis- shapeand position of the phasmids; Nacobbus was tinct from procorpus, with valve prominent. Oesopha- considered as constituting a separate family, Nacobbi- geal glands lobe-like overlapping anterior end of intes- dae. tine (except some species of Pratylenchoides with oeso- From this history, it can be stated that : phageal glandsabutting with almost no overlap overthe - there is a consensus among the authors on the intestine). Oesophago-intestinal valve not welldevel- genera that constitute the pratylenchids, except for Na- oped (except Prutylenchoides and Apratylenchoides). cobbus, because of its saccate female, and Hoplotylus Female genital tract singleor double. ‘Tricolumellar which for some authors shows more affinities with uterus. No vulval flaps, or epiptygmata. Sperms globu- Hoplolaimidae; lar or more rarely rod-like. Spicules plain. - the divisionof pratylenchids into subfamilies Gubernaculum plain, not protruding (except Rado- and/or families appears very controversial among these pholus). Caudal