Xiphinema elongatum

Female. Body ‘J’ shaped, cylindrical, tapering towards the anterior end but more to the posterior end. Cuticle smooth, 1.6–2.3 μm thick at neck region, 2.3–3.1 μm at mid body and 5.5–6.3 μm at tail region. Lip region, well demarcated. Amphidial aperture on lip region 50–59% of lip width. Amphidial fovea stirrup–shaped. Guiding ring, about 1/4th of the total odontostyle length from the base of odontostyle. Odontostyle, 1.6 μm diameter, 66±3 (63–73) % of total stylet length and furcated at base. Odontophore well developed with prominent basal flanges 10.9–11.7 μm wide. Lip width 3.1 ±0.5 (2.5–4.2) % of total stylet length. Female reproductive system amphidelphic, didelphic, branches equally developed. Ovaries reflexed. Pars dilatata oviductus separated from the uterus by a very robust sphincter muscle. No uterus differentiation. Vagina about half body width and perpendicular to the body axis. Vulva, 41% of body length from anterior end. Tail, conoid to dorsally convex conoid, non-digitate, terminal hyaline portion about 27% of tail length (Fig. 1). The description of Xiphinema elongatum has been recorded by a number of authors and well studied. It was originally described by Schuurmans Stekhoven and Teunissen (1938) from a single female specimen from Rutshuru (Zaire) and redescribed by many authors such as Tarjan and Luc (1963), Williams (1959), Carvalho (1962), Timm (1965), Cohn and Sher (1972), Loof and Maas (1972), Heyns (1974), Williams and Luc (1977) and Loof and Sharma (1979), and also lately by Loof and Luc (1990). The morphometric data of described Ethiopian specimens were perfectly fit within the twenty-two populations of Xiphinema elongatum recorded by Luc and Southey (1980) from a different country and are fairly similar to records of Xiphinema elongatum from Botswana (Heyns and Coomans 1991), Guiana and Martinique (Luc and Coomans 1992) and Taiwan (Chen et al. 2004). According to Luc and Southey (1980), Xiphinema elongatum appears to have continuous pattern of variation for some morphometric data and shape of tail over different populations of different geographic location. These authors divided Xiphinema elongatum into two groups upon morphological variation over different geographical locations. The first group, characterized by a shorter tail and longer stylet, all originate from West Africa whereas the second, having a longer tail and shorter stylet, are mainly from east Africa or South East Asia/ Pacific area. According to this suggestion the studied specimen best fit with the second population group of Xiphinema elongatum. This species was reported as widespread and common in Africa including neighbor country Kenya (Luc and Southey 1980; Heyns and Coomans 1991; Coomans et al. 2001). Accordingly, it belongs to group 7 of the species group, characterized by equal female genital branches, without uterine differentiation, and tail elongate to conical. As the revised polytomous key by Loof and Luc (1990), on note 22, Xiphinema elongatum cannot be separated clearly by the characters used in the key. But they can be differentiated by: c’ = 1.9–3.3; total spear length = 134–178 μm which perfectly fit with the studied Ethiopian specimen. Male. Not found. Alpha-numeric codes of the polytomous identification key for Xiphinema species by Loof and Luc (1990) of Xiphinema elongatum and the studied specimens. Characters A B C D E F G H I J K L The studied specimen 4 4 2 3 34 2 1 3 3 - - 1 Loof and Luc (1990) key 4 4 23 34 2345 23 12 2 3 2 2 1 Morphometric measurements of Xiphinema elongatum and Xiphinema pachtaicum. All measurements are in µm, measurements presented as mean ± standard deviation (range). Xiphinema elongatum (♀) Xiphinema pachtaicum (♀) n 4 12 L 2380±71 (2330–2430) 1937±103 (1732–2096) a 69±7 (64–74) 70±3.6 (64–75) b 7.2±0.5 (6.9–7.6) 7.3±0.6 (6.4–8.2) c 33.2±5.8 (29.1–37.3) 63±5.1(55–71) c’ 2.7±0.1 (2.6–2.8) 1.9±0.2 (1.6–2.2) V 41.3 ± 0.3 (41–41.7) 57±1 (56–58) Lip width 11±1 (10–11) 8±1 (7–10) Odontostyle 78±12 (70–86) 89±3 (85–97) Odontophore 51±7 (46–55) 46±5 (33–51) Pharynx 329±11 (321–337) 266±25 (232–329) Body width 35±2 (33–36) 28±2 (25–30) Anal body width 22±3 (20–24) 17±1 (15–18) Tail 65.1±2.7 (62.5–68) 31±2 (27–36)