FRESHWATER NEMATODES FROM LOCH NESS 



DESCRIPTIONS OF SPECIES 



Aglenchus agricola (de Man, 1884) Andrassy, 1954 



(Fig. 2) 



Material examined. Fort Augustus Bay: 92, 105 m; cores 2, 3; 

 29$. Foyers Plateau: 150-161 m; cores 14-17; 299 46*6*. River 

 Foyers: 0.14-0.39 m; cores 40, 43, 45: 2 99, 266. 



Horizon. Core 2 (2-3 cm), core 14 (3^4 cm), core 40 (2-3 cm). 



Females, (n = 5). L = 650 urn (625-667): a = 31 (26.4-34.4); b = 

 6.6 (6.3-6.9); c = 3.3 (3.2-3.4); c' = 14.5 ( 1 2.7-1 5.8); V = 55. 1 (53- 

 56); V = 77.6 (76.5-78.4); tail/V-a = 1.9 (1.7-2.0): tail = 194 \im 

 (188-200). 



Head continuous, not annulated. Body annules 1.6-1.8 urn wide 

 at mid-body. Lateral fields with three lines; outer lines sometimes 

 appear double, whereas the inner line which is usually weakly 

 expressed, could be interpreted as two lines very closely set as they 

 appear as either gully or ridge-like (dependent on optical settings). 

 Spear moderately robust, 11.0-12.8 urn long, basal knobs distinct 

 about 3.2 urn wide. Oesophagus 92.7-101.7 um long; median bulb 

 ovoid with usually distinct valves at 44-50% of oesophageal length. 

 Vulva with flaps about 5.0 um long covering about three annules; 

 vagina curved anteriorly with swollen pyriform walls; anterior 



Fig. 2 Aglenchus agricola (de Man, 1884). A-E, female. A, oesophageal 

 region; B, posterior end of reproductive system; C. tail; D, lateral field; 

 E, habitus: F, male spicular region. Scale bars a = 20 |jm, b = 40 |jm, c = 

 100 um. 



genital branch 123-146 um long; spermatheca partly offset, usually 

 poorly defined, ovoid to elongate-ovoid, sometimes appearing 

 double, length variable 20-25.6 um; postuterine sac lacking. 



Males, (n = 6). L = 591 .5 |jm (469-670); a = 38.9 (33^3); b (n 

 - 4) = 6.2 (5.6-6.7); c = 3.1 (2.9-3.3); c' = 17.5 (15.3-19); 

 gubernaculum (n = 5) = 6.4 um (6.3-6.4); spicules (n = 5) = 14.7 um 

 (14-15.3); tail = 193.8 urn (153-219). 



Similar to female. Annules 1.6-1.96 um wide at mid-body. Spear 

 12-12.8 um long, with rounded knobs about 2.6 um wide. Oesopha- 

 gus 81.6-101 um long; median bulb ovoid with usually distinct 

 valves at 46^-8% of oesophageal length. Testis 144-153.6 um long 

 occupying 24—25% of body length; cloacal lips tube-like, somewhat 

 asymmetrical; bursa adanal 32-38.4 um long with smooth or very 

 finely crenate margins. 



Distribution and habitat. Cosmopolitan, in various soils, lives 

 on or near plant roots, in mosses and freshwater. 



REMARKS. Morphometric measurements of this population fall 

 midway between those of two very similar species, A. agricola and 

 A. muktii Phukan & Sanwal, 1980. A. tnuktii, according to the 

 original authors, is distinguished from A. agricola 'in having a non- 

 annulated lip region, 3 incisures in the lateral field, and a very long 

 filiform tail. (A. agricola has 3 annules in the lip region, 1 lateral 

 incisures and a tail which is not as filiform as in A. muktii).' Of these 

 characters the first two are mistaken because in A. agricola the head 

 is not annulated and the lateral field is comprised of three lines. In 

 practice A. muktii is distinguished from A. agricola by its very long 

 filiform tail. Tail length in A. agricola ranges from 134 to 179 um, 

 whereas in A. muktii the range is 178-276 um (Geraert & Raski. 

 1988). Female tail length of this population varies between 153-197 

 um. Br/eski (pers. comm.) notes tail lengths of A. agricola varying 

 from 134-208 um. In males of both species there would appear to be 

 a distinction between tail lengths and ratio c'. Tail length 140-169 

 um in A. agricola vs 1 78-330 um in A. muktii: ratio c' 13-15 vs 22- 

 25 in A. muktii. However the Loch Ness males bridge the gap in 

 respect of tail length 153-219 urn and fall between the range of 

 values in the case of ratio c', c' = 15.3-19. 



The overlap in tail lengths and other morphometric measurements 

 suggest that the specific status of A. muktii is doubtful. This popu- 

 lation is therefore identified as A. agricola. 



Coslenchus polonicus Brzeski, 1982 



(Fig. 3) 



Material examined. Deep South Basin: 204 m; core 9; 1 9. 

 River Foyers: 0.22 m; core 40; 1 9. 



Horizon. Core 40, (1-2 cm) 



Females, (n = 2). L = 635, 744 um; a = 41 .5, 46.5; b = 5.4, 6.2; c 

 = 5.8,5.4;c'=ll,12;V = 65.8,64;V' = 79.6,80;Rex = 47,52;Roes 

 = 62, 63; Rv = 203; Rvan - 44. 49; Ran = 55, 65; tail/V-a = 1 .0; tail 

 = 110, 137.6 um. 



Head more or less continuous with body contour, 6.4-6.7 um 

 wide with 4 very fine annules. Annules 2.3, 2.8 um at mid-body. 

 Lateral fields with 4 lines, the two inner lines closely spaced, thus 

 sometimes appearing as a single line. Cuticle with 18-20 longitudi- 

 nal ridges (difficult to count) excluding lateral fields. Spear robust 

 15, 13.4 um long; knobs rounded, 3.8, 3.2 um wide. Oesophagus 

 118, 120 um long; median bulb ovoid, valve at about 45% of 

 oesophageal length. Vulva, with lateral vulval membranes, 6.4 um 

 long or about 3 annules wide; vagina inclined anteriorly with thick, 

 somewhat pyriform, walls; postuterine sac small; spermatheca 



