Dalhousie Springs hydrobiids 
arrisi. A, Spring Са13А, E, Spring Са7 (station C644). В- 
Fi 
Іше 10. Radulae of Dalhousia species. А,Е. Dalhousia h 
DP D. globosa, Spring Cal [station 641 (B,C) and Cal We (D,F)]. Scales 0.02mm. 
Remarks, This species is distinguishable from D. globosa, when in sympatry, by its generally smaller 
176 (Fig. 16D, 22A) and taller spire. It lives in sympatry with D. globosa іп springs Cal, А1, A2, 
I 8, B1, Ca8, Cc1, Cc3, and Cdl. Hybrids have been found in Ca8 and Cd2 (Appendix 3, Table 8). 
п Cal it has been found only on the edges of the large pool where it is effectively out of reach of the 
pea which are known to eat hydrobiid snails (Ponder, 1989). Other than the shell characters, 
ere аге no obvious, consistent morphological synapomorphies which separate this species from D. 
8lobosa, although in the type population the anteriorly placed bursal duct is a consistent difference. 
e e distribution of this character was checked in all other populations and was found to be ventrally 
О Posteriorly placed, as іп D. globosa. The capsule gland has more distinct glandular zones in D. 
arisi than іп D. globosa in most populations, but, again, this is not consistent. The genetic 
d in the diagnosis and detailed below. Allozyme 
d ^ 
ferences between these two taxa are summarize ) 
tiation within this taxon is also detailed below (see also Appendix 3, Table 8). 
