FRESHWATER NEMATODES FROM LOCH NESS 



11 



Fig. 13 Lelenchus sp. A-C. F. female. A, oesophageal region; B, tail; C. 

 habitus; F. vulval region. D. E. male. D. habitus; E. spicular region. 

 Scale bars a = 20 um, b = 30 urn. c = 100 um. 



Cephalic region narrowed dorso-ventrally. Cuticle smooth by 

 light microscopy. Lateral field absent. Spear slender, poorly defined. 

 9.0-9.3 um long (n = 2) with small rounded knobs about 1.3 um 

 wide. Oesophagus 92-118 um long; median bulb spindle-shaped, 

 valves very indistinct, at about 48% of oesophageal length. Anterior 

 genital branch 175-250 um long. Spermatheca elongate ovoid 

 without sperm. Egg present in two specimens about 62 um long by 

 10 um wide. Postuterine sac about 1 1.5 um long or 80% of vulval 

 body width (n = 2). Vagina more or less perpendicular, about 7.7 um 

 long with slightly thickened walls. 



MALE, (n = 1). L = 920 um; a = 58; b = 6.4; c = 4.5; c' = 19.5; 

 spicules = 23 um; gubernaculum = 6.5 um; tail = 203 um. 



Similar to female except body longer and more slender. Spear 

 indistinct, about 1 um long, with small, possibly deformed, rounded 

 knobs. Oesophagus 145 um long; median bulb spindle-shaped with 

 indistinct valves at 40% of oesophageal length. Testis 300um long, 

 occupying 32.6% of body length; bursa adanal about 38 um long 

 with smooth margins. 



Remarks. These nematodes are possibly conspecific with L. 

 leptosoma, but for the present they are treated as a separate species. 

 In females the vagina walls are thicker and generally more pro- 

 nounced. The male differs from males of L. leptosoma described in 

 the literature by its greater body length and longer, strongly curved, 

 almost bent spicules. 



Malenchus acarayensis Andrassy, 1968 Geraert & Raski, 

 1986. 



(Fig. 14) 



Material examined. Fort Augustus Bay: 92 m; core 3, 1 9. Foy- 

 ers Plateau: 159. 160 m; coresl4, 15, 3 99. River Foyers: 0.39 m; 

 core 42, 1 9. 



Horizon. Core 14 (2-3 cm). 



Females, (n = 5). L = 352 um (323-373); a = 24.7 (23-26.6); b 

 (n=3) = 4.4 (4.3-4.6); c = 4.4 (4.0-4.9); c' = 9. 1 (8-10. 1 ); V = 63.3 

 (61-66.4); V = 80.8 (79-82); tail/V-a =1.5(1 .25-1 .73). tail = 78.9 

 pm (71.7-92). 



Head narrow, about 4.0-5.0 um at base, with very fine annules. 

 Amphids not clear. Annules 1.0-1.3 um at mid-body. Lateral fields 

 with two lines appearing smooth or crenate, depending on fine 

 focus; originating between 6.4-7.0 um posterior to spear base, 

 ending at 27-33% of tail length. Spear fine, especially conus, 8.3- 

 9.0 um long, knobs small, sloping posteriorly, about 1.3 um wide. 

 Excretory pore 56-66 um from anterior. Oesophagus 73.6-86 um (n 

 = 3 ) long; median bulb ovoid, valve hardly evident, but positioned at 

 44-47.8% of oesophageal length. Anterior genital branch 101-112 

 um long. Spermatheca usually rounded, ovoid in one specimen, 9.6- 

 12.8 um wide. Postuterine sac 6.4 um long or 43% of vulval body 

 width (n=l), collapsed in other specimens. Vagina with thickened 

 walls, perpendicular to body axis or slightly tilted anteriorly. Dis- 

 tance from vulva to anus 45-56.9 um. Tail tip slightly to strongly 

 curved, tapering to a fine point, but not thread-like. 



DISTRIBUTION AND HABITAT. Described from N. and S. America. 



Fig. 14 Malenchus acarayensis Andrassy. 1968. A-F, female. A, 



oesophageal region; B, habitus; C, posterior end of reproductive system; 

 D, tail; E. F. lateral field at different focal levels. Scale bars a = 10 pm, 

 b = 50 pm. 



