Dalhousie Springs hydrobiids 
Fi " 222 4 ; 
100ге 15. Distribution of Dalhousia species and Fluvidona centralia. A. D. globosa. B. D. harrisi. C. F. centralia. 
One of the large springs. It has not been found living in sympatry with Dalhousia. 
Remarks, This species is readily distinguished from the somewhat similar forms of D. да wie 
Т all, conical shells in having a more evenly conical spire outline. In addition, F. centralia и as 
is m both species of Dalhousia in having more prominent opercular pegs, multiple (пойро) аѕа 
GES оп the central teeth and there are considerable differences in the female genita! system 
"раге Figs 14 and 20) and penial morphology (compare Fig. 12C,D). 
Apart from the type population, a sample from a lower, cold outflow from a large spring (El, stn. 
Was also examined in detail but proved (unlike the type population) to be heavily parasitised. 
© external features of the animal show the same ciliation patterns but the opercula differ in having 
SR numerous pegs (2-7, mean 4.2) than the Cd11 sample. Radulae also differed, having fewer 
SA (4-5, usually 4 on each side of median cusp оп central teeth; 4 on inner side of lateral teeth 
n 4— on outer side; 18-21 cusps on inner marginals and 26-32 on outer marginals). Unfortunately 
ES Of the other samples contained insufficient material for detailed analysis so the range of 
ation within most populations of this taxon has not been adequately ascertained. Given the 
Шегепсез between the Cd11 and E1 populations, further work may well show that subdivision of 
15 taxon is possible and this is also suggested by the level of genetic variation within the taxon 
\eseribed below). In addition, given the nature of the localities frequented by this taxon, it is 
p doubtedly under represented in our sampling. The small seepages are often difficult to locate due 
0 the dense vegetation and can be very easily missed. In addition, sampling the cold outflows of the 
