The who, what and where of longidoridae and trichodoridae.

Longidoridae and Trichodoridae represent the only families of nematodes within the Class Enoplea proven to be plant-parasitic. The Longidoridae are classified within the subclass Dorylaimia (order Dorylaimida, superfamily Dorylaimoidea), while the Trichodoridae belong to the subclass Enoplia (order Triplonchida, superfamily Diphtherophoroidea). Longidoridae: The family Longidoridae includes some 480 species of the subfamily Longidorinae with six genera: Longidorus (144 spp.), Longidoroides (13 spp.) and Paralongidorus (72 spp.) in the tribe Longidorini, and Australodorus (1 sp.), Paraxiphidorus (3 spp.) and Xiphidorus (8 spp.) in the tribe Xiphidorini and the subfamily Xiphineminae with one genus Xiphinema (some 240 spp.). At present, there is no consensus about the status of the genus Longidoroides Khan, Chawla and Saha, 1978 (see Decraemer and Coomans, 2007). Longidorus, Paralongidorus and Xiphinema are virus vectors. A wealth of information on Longidorus, Paralongidorus and Xiphinema can the found in papers on polytomous keys and subsequent supplements: Xiphinema (Loof and Luc, 1990; Loof and Luc, 1993; Loof et al., 1996), Longidorus (Chen et al., 1997; Loof and Chen, 1999) and Paralongidorus (Escuer and Arias, 1997) as well as in Coomans et al. (2001), a monography on the genus Xiphinema dealing with character analysis, phylogeny and biogeography. The main diagnostic features of Longidoridae at the genus level are the structure of the odontostyle and odontophore, the structure and position of the guide ring, the shape of the amphidial fovea, shape and size of amphid opening and the position and size of the pharyngeal gland nuclei. Additional features at species level next to morphometric data are the shape and size of the amphidial fovea and opening, the development and structure of the female reproductive system (didelphic, monodelphic, pseudomonodelphic) with uterine differentiation and inclusions in Xiphinema and genera of the Xiphidorini, the tail shape in all developmental stages and presence or absence of males. Phylogenetic analyses of the Longidoridae based on sequence data and morphological data were carried out by He et al. (2003). Olivera and Neilson (2004) have a comprehensive review article showing the systematics, virus vectoring species and morphological differences among the Longidorid genera, and Decraemer and Coomans (2007) discussed relationships within the family Longidoridae. Trichodoridae: The Trichodoridae include 100 species and five genera: Trichodorus Cobb, 1913, Paratrichodorus Siddiqi, 1974, Monotrichodorus Andrassy, 1976, Allotrichodorus Rodriguez-M, Sher and Siddiqi, 1978 and Ecuadorus Siddiqi, 2002. The two largest genera Trichodorus (54 spp.) and Paratrichodorus (34 spp.) are didelphic in females and occur worldwide. The three remaining genera, Monotrichodorus (4 spp., one subspecies), Allotrichodorus (6 spp.) and Ecuadorus (2 spp.), have fewer species, and females are monodelphicprodelphic; so far, these three genera have only been recorded from Central America and the northern part of South America. The main diagnostic characters to differentiate the genera of the Trichodoridae are: in females, (i) the reproductive system (didelphic or monodelphic); (ii) length of vagina, (iii) development of vaginal sclerotized pieces and (iv) presence of advulvar lateral body pores; and in males, (i) presence or absence of caudal alae, (ii) degree of development of copulatory muscles and related habitus and (iii) development of capsule of spicule suspensor muscles (Decraemer and Geraert, 2006). Additional features at species level, apart from morphometric data, are: in females, (i) the vaginal sclerotized pieces (size, shape, orientation, distance), (ii) presence/absence and location of sperm cells; in males and females, structure of sperm cell and nucleus, and in males, (i) the spicules (shape, ornamentation), (ii) number and arrangement of ventromedian cervical papillae and (iii) ventromedian precloacal supplements. Decraemer (1995) gives a comprehensive review of morphological and systematic information on this group.