The occurrence and geographic distribution of Xiphinema and Xiphidorus species (Nematoda: Longidoridae) in Brazil

Abstract

41 Summary The occurrence and geographic distribution of Xiphinema and Xiphidorus species were investigated during a national survey of 16 Brazilian States between 1999 and 2001. Eighty-two soil samples were collected from different habitats, including crop plants, grassland, savanna (cerra-do) and typical Amazonian forest vegetation. Fourteen Xi-phinema species ( X. brasiliense, X. brevicolle, X. elonga-tum, X. ensiculiferum, X. ifacolum, X. krugi, X. longicau-datum, X. paritaliae, X. setariae/vulgare complex , X. suri-namense, X. variegatum, and three morphotypes of X. ame-ricanum sensu lato identified as representing X. diffusum, X. oxycaudatum and X. peruvianum ) were recorded. Also, Xiphidorus balcarceanus , X. minor , X. yepesara parthenus and X. yepesara yepesara were identified from three States, however recognition of X. yepesara parthenus as a subspecies of X. yepesara requires confirmation. The most frequently occurring species were X. krugi (46 % of all samples), X. brasiliense (22 %) and X. setariae/vulgare complex (22 %). Xiphinema diffusum, X. longicaudatum, X. oxycaudatum, X. peruvianum and Xiphidorus balcar-ceanus constitute new records for Brazil. A principal com-ponent analysis identified odontostyle and odontophore length and to a lesser extent vulva position as the main influencing morphological characters that could be used to separate the Xiphinema and Xiphidorus species recorded in this study. A dichotomous key for the identification of Xiphinema species reported in Brazil is presented. Keywords: identification key; survey; taxonomy; virus vector nematodes; Xiphidorus; Xiphinema Introduction Xiphinema nematodes have a world-wide distribution and cause substantial damage to an extensive range of crop plants by their direct feeding on plant root cells (Taylor and Brown, 1997; Weischer and Brown, 2000) and affect-ing plant growth (Lamberti et al. 1987a; 1992a; 1992b; 1993; Leone et al., 1997; 1999). Also, several of these spe-cies are important economically as they are efficient vec-tors of several members of the genus Nepovirus that cause diseases in a wide range of fruit and vegetable crops (Brown et al. , 1995, 1996). In a comprehensive review, Doucet et al. (1998) reported that forty-two Xiphinema species occur in Latin America, with twenty-two (X. basiri, X. brasiliense, X. brevicolle, X. californicum, X. clavicaudatum, X. costaricense, X. dimi-diatum, X. elongatum, X. ensuculiferum, X. fluminense, X. georgianum, X. guillaumeti, X. ifacolum, X. index, X. kru-gi, X. machoni, X. pachtaicum, X. parasetariae, X. parita-liae, X. paulistanum, X. setariae/X. vulgare complex and X. surinamense ), including several virus-vector species, having been recorded in Brazil. Recently, another three species of Xiphinema ( X. torvum, X. variegatum and X. vi-carium) were reported from Brazil (Siddiqi, 2000). Xiphidorus nematodes that are indigenous to Latin Ameri-ca have a more restricted distribution as compared with Xiphinema, and the economic importance of these nemato-des with respect to crop damage is unknown (Leone et al., 1999). Currently, only eight Xiphidorus species have been identified from the following South American countries: Argentina, Brazil, Uruguay and Venezuela (Decraemer et al. , 1996; Coomans et al. , 1996; Doucet et al. , 1998; Lam-berti et al. , 1999) and an undescribed species from Bolivia (Hunt, 1993). In Brazil, X. amazonensis, X. minor, X. yepe-sara parthenus, and X. yepesara yepesara have been pre-viously recorded (Doucet et al. , 1998). Here we present data from a national survey of 16 Brazi-H