View metadata, citation and similar papers at core.ac.uk brought to you by CORE Journal of Nematologyprovided by 39(4):295–297. Ghent University Academic 2007. Bibliography © The Society of Nematologists 2007. The Who, What and Where of Longidoridae and Trichodoridae Wilfrida Decraemer,1 R. T. Robbins2 WHO:LONGIDORIDAE AND TRICHODORIDAE ing species and morphological differences among the Longidorid genera, and Decraemer and Coomans Longidoridae and Trichodoridae represent the only (2007) discussed relationships within the family families of nematodes within the Class Enoplea proven Longidoridae. to be plant-parasitic. The Longidoridae are classified Trichodoridae: The Trichodoridae include 100 species within the subclass Dorylaimia (order Dorylaimida, su- and five genera: Trichodorus Cobb, 1913, Paratrichodorus perfamily Dorylaimoidea), while the Trichodoridae be- Siddiqi, 1974, Monotrichodorus Andrassy, 1976, Allotri- long to the subclass Enoplia (order Triplonchida, su- chodorus Rodriguez-M, Sher and Siddiqi, 1978 and perfamily Diphtherophoroidea). Ecuadorus Siddiqi, 2002. The two largest genera Tricho- Longidoridae: The family Longidoridae includes some dorus (54 spp.) and Paratrichodorus (34 spp.) are didel- 480 species of the subfamily Longidorinae with six gen- phic in females and occur worldwide. The three re- era: Longidorus (144 spp.), Longidoroides (13 spp.) and maining genera, Monotrichodorus (4 spp., one subspe- Paralongidorus (72 spp.) in the tribe Longidorini, and cies), Allotrichodorus (6 spp.) and Ecuadorus (2 spp.), Australodorus (1 sp.), Paraxiphidorus (3 spp.) and Xiphi- have fewer species, and females are monodelphic- dorus (8 spp.) in the tribe Xiphidorini and the subfam- prodelphic; so far, these three genera have only been ily Xiphineminae with one genus Xiphinema (some 240 recorded from Central America and the northern part spp.). At present, there is no consensus about the status of South America. of the genus Longidoroides Khan, Chawla and Saha, 1978 The main diagnostic characters to differentiate the (see Decraemer and Coomans, 2007). Longidorus, Para- genera of the Trichodoridae are: in females, (i) the longidorus and Xiphinema are virus vectors. A wealth of reproductive system (didelphic or monodelphic); (ii) information on Longidorus, Paralongidorus and Xiphi- length of vagina, (iii) development of vaginal sclero- nema can the found in papers on polytomous keys and tized pieces and (iv) presence of advulvar lateral body subsequent supplements: Xiphinema (Loof and Luc, pores; and in males, (i) presence or absence of caudal 1990; Loof and Luc, 1993; Loof et al., 1996), Longidorus alae, (ii) degree of development of copulatory muscles (Chen et al., 1997; Loof and Chen, 1999) and Para- and related habitus and (iii) development of capsule of longidorus (Escuer and Arias, 1997) as well as in Coo- spicule suspensor muscles (Decraemer and Geraert, mans et al. (2001), a monography on the genus Xiphi- 2006). Additional features at species level, apart from nema dealing with character analysis, phylogeny and morphometric data, are: in females, (i) the vaginal scle- biogeography. rotized pieces (size, shape, orientation, distance), (ii) The main diagnostic features of Longidoridae at the presence/absence and location of sperm cells; in males genus level are the structure of the odontostyle and and females, structure of sperm cell and nucleus, and odontophore, the structure and position of the guide in males, (i) the spicules (shape, ornamentation), (ii) ring, the shape of the amphidial fovea, shape and size number and arrangement of ventromedian cervical pa- of amphid opening and the position and size of the pillae and (iii) ventromedian precloacal supplements. pharyngeal gland nuclei. Additional features at species Decraemer (1995) gives a comprehensive review of level next to morphometric data are the shape and size morphological and systematic information on this of the amphidial fovea and opening, the development group. and structure of the female reproductive system (didel- phic, monodelphic, pseudomonodelphic) with uterine WHAT:VIRUS VECTORS differentiation and inclusions in Xiphinema and genera The Longidoridae and Trichodoridae are polypha- of the Xiphidorini, the tail shape in all developmental gous root-ectoparasites and are the only plant-parasitic stages and presence or absence of males. Phylogenetic Nematoda that transmit plant viruses. Their associated analyses of the Longidoridae based on sequence data viruses belong to different virus taxa. Longidorids vec- and morphological data were carried out by He et al. tor nepoviruses; whereas trichodorids vector Tobravi- (2003). Olivera and Neilson (2004) have a comprehen- ruses (Taylor and Brown, 1997). sive review article showing the systematics, virus vector- Longidoridae: Of the 38 known nepoviruses, 13 have been proven to be naturally transmitted by Longi- Received for publication November 20, 2007. doridae: seven by Longidorus species, one by Paralongi- 1 Royal Belgian Institute of Natural Sciences, Brussels, Belgium. dorus and nine by Xiphinema species. Thus, only 5% of 2 University of Arkansas, Fayetteville, AR. A paper given at the symposium on Systematics and Phylogeny: “The Tree of the known species of Longidoridae have been shown to Life, Dorylaimina, Triplonchida and the Origin of Nematodes” at the joint transmit nepoviruses. The North American Xiphinema meeting of APS and SON at San Diego, CA, July 28-August1, 2007. E-mail: [email protected] species, and more specifically the X. americanum species This paper was edited by David Bird. group, seems to present the main source of virus vec- 295 296 Journal of Nematology, Volume 39, No. 4, December 2007 toring, i.e., three vector species of the X. non-ameri- The genus Paralongidorus (incl. Longidoroides) has canum-group (X. index, X. diversicaudatum, X. italiae) vs. been reported mainly from India (34 spp.) and South six putative species of the X. americanum group (X. Africa (29 spp.). In Europe, nine species have been americanum s.str., X. californicum, X. bricolense, X. interme- recorded, and three from Australia. In the Americas, dium, X. revesi, X. tarjanense). In North America, the only two species have been reported, both in North four nepoviruses cherry rasp leaf, peach rosette mosaic, America. Ninety percent of the Paralongidorus species tobacco ringspot and tomato ringspot are transmitted were recorded only once or, if several times, then from by members of the Xiphinema americanum group of spe- within a restricted area, 5% from two continents, and cies. These viruses cause substantial damage to a wide no cosmopolitan species has been found. range of fruit and vegetable crops (Taylor and Brown, The genus Longidoroides has been reported mainly in 1997). India and South Africa. The range of the genera Aus- Trichodoridae: All tobraviruses are transmitted by tralodorus, Paraxiphidorus and Xiphidorus is limited to trichodorid vector species. Only the didelphic tricho- South America, with Xiphidorus being the most widely dorid genera possess virus vector species. Out of 54 distributed (Argentina, Brazil, Uruguay and Venezu- Trichodorus and 34 Paratrichodorus species, 7% (four: T. ela). primitivus, T. similis, T. cylindricus and T. viruliferus) and The genus Xiphinema is the most diversified genus of 26% (nine: P. anemones, P. divergens, P. hispanus, P. na- the family Longidoridae with both species groups, the nus, P. pachydermus, P. teres, P. tunisiensis, P. allius, P. X. americanum-group and the non-americanum-group, oc- minor, P. porosus) are vectors of tobraviruses, respec- curring worldwide. Lamberti et al. (2000) gave an over- tively. For Europe, however, the percentages of virus view of the geographic distribution of the X. america- vectors vs. non-vectors are much greater; 67% for Para- num-group. A nearly equal number of species has been trichodorus and 27% for Trichodorus. Further, in nearly reported from North America (21) and Asia (22), fol- all European countries, vector species and virus are lowed by 17 for Europe, 11 for South America, 10 for present (Ploeg and Decraemer, 1996). This supports Africa and three for Australia. However, 50% or more the hypothesis that Trichodorus vector/virus association of the species are considered rare species or of ques- probably evolved in Europe. The presence of these vec- tionable identification. The largest number of common tor species in North America is very restricted and ap- species is found in North America (10) and Europe (8). parently the result of introduction with imported plant The biogeographic distribution of the Xiphinema non- material. Similar remarks can be made for P. pachyder- americanum species group was studied in detail in Coo- mus, P. anemones, P. teres, P. divergens, P. hispanus, P. mans et al. (2001). The authors divided the species into nanus and P. tunisiensis, all species whose main occur- four groups: (1) species recorded only once or, when rence is restricted to Europe and Mediterranean coun- recorded more, only from a restricted area, (2) species tries. For P. porosus, the vector aspect is based on labo- recorded in different areas but close to each other or ratory experiments. The vector species P. allius and P. belonging to the same climatic unit, (3) species found minor apparently developed a virus/vector relationship in two continents and (4) ‘cosmopolitan’ species from outside Europe and, with P. minor, possess a unique at least three different continents. Xiphinema species association with pepper ringspot