F.R. WANLESS AND R. HUNTER 



Filenchus facultativus (Szczygiel, 1969) Raski & Geraert, 

 1987 



(Fig. 7) 



Material examined. Fort Augustus Bay: 91, 



3$?. 



Horizon. Core 2, (2-3 cm). 



m; cores 2, 5; 



Females. (n = 3).L = 515um(434-557);a = 36(35-37.8);b = 6.1 

 (6.0-6.3); c = 4.0 (3.9-4.1); c'= 13 (11.6-14.5); V = 63.2 (62-64.6); 

 V = 84.8.(83.7-85.6); tail/V-a = 2. 1 (2.0-2.2); tail = 127 um (105- 

 142). 



Head about 4.6 um wide at base with 2-3 annules. Amphids 

 sinuous. Annules 1.7 um (1.5-1.9) at mid body. Lateral fields with 

 two lines. Spear slender 9.0 um (n = 2) long with small basal knobs, 

 about 1.2um wide. Oesophagus 83.8 um (73.6-91) long; median 

 bulb ovoid, valve weak at 39^12% of oesophageal length. Excretory 

 pore 62.4, 68.7 um (n = 2) from anterior. Anterior genital branch 145 

 um (127-159) long. Spermatheca axial or slightly offset, elongate 

 23, 26 um long with rounded sperms (n = 2). Postuterine sac 7.7-12 

 um long. Vagina 7.0-8.0 urn long, more or less perpendicular to 

 body axis. Tail tip pointed to finely rounded. 



Distribution and habitat. 

 restrial soils. 



A widespread species found in ter- 



Remarks. F. facultativus is a variable species and these nema- 

 todes are within the range of measurements of other populations 

 described in the literature. However, the spear at 9.0 um long is at the 

 extreem range recorded for this species (6.0-9.0 um.). A range of 

 6.0-8.0 um is given by Raski & Geraert (1987) in their key to 



species of Filenchus, the same range is also given by Karegar & 

 Geraert (1988) in their summary of characters distinguishing F. 

 facultativus from other very similar species, whereas Torres & 

 Geraert (1996) record spear lengths of 7.5-9.0 um in a population 

 described from Argentina. 



Filenchus thornei (Andrassy, 1954) Andrassy, 1963 



(Fig. 8) 



Material examined. Deep South Basin: 161 m; core 19, 19. 

 River Foyers: 0.22 m; core 40, 1 2. Foyers Plateau: 159 m; core 14, 

 1<J. 



Horizon. 

 cm). 



Core 14, (2-3 cm); core 19, (1-2 cm); core 40, (2-3 



Females, (n = 2). L = 997, 1003 um; a = 38, 44.7; b = 6.9, 6.5; c 

 = 5.0, 4.1; c'= 14.5. 18; V = 59, 56; V = 73, 73.5; tail/V-a = 0.95, 

 1.16; tail = 131.5, 191.5 um. 



Head about 7.6, 8.0 um wide at base with 3-4 annules; height 

 about 3.5 um. Amphids not observed. Annules 1.3-1.6 um wide at 

 mid-body. Lateral fields with four lines, inner lines very faint and 

 not always evident. Spear distinct, moderately slender, 13.4, 12 um 

 long with small basal knobs about 2.0 urn wide. Oesophagus 144- 

 155 um long; median bulb more or less ovoid, valves moderately 

 distinct at 39.7, 42% of oesophageal length. Excretory pore 

 sclerotized at 112, 122 um from anterior. Anterior genital branch 

 432 urn (n = 1 ); spermatheca 42 um long, offset. Vagina perpendicu- 

 lar to body axis about 13.5 um long. Tail tip finely pointed. 



F - 



Fig. 7 Filenchus facultativus (Szczygiel, 1969). A-G, female. A. 

 oesophageal region; B, head showing amphid; C, posterior end of 

 reproductive system; D, lateral field; E, reproductive system; F, tail 

 terminus; G, habitus. Scale bars a = 10 urn, b = 30 um, c = 100 um. 



Fig. 8 Filenchus thornei (Andrassy, 1954). A-E, female. A, habitus; B, 

 posterior end of reproductive system; C, tail; D, head region; E, 

 oesophageal region. F, male spicular region. Scale bars a = 200 urn, b = 

 30 urn, c = 20 um. 



