L. fabalis dwarf form; heights 4 mm to 5.5 mm.
Other views of same shells at 28Dof 28 Differentiation L. obtusata/L. fabalis & 43Dof 43 Differentiation L. obtusata/L. fabalis
Sample of eight dwarf specimens from exposed shore (Ballantine scale 3).
IFS was uncertain of identity as penes not examined and shell form unfamiliar, but wide experience of Dr Reid enabled him to confirm the identification. Usually neither species is common or large at such exposure, but L. fabalis is more likely. On some Scottish exposed shores with frequent splash and spray, it “may be found further up on the shore on other fucoids where there is adequate protection from desiccation” (McKay & Smith, 1979). It even sometimes occurs at mean high water neap level on Fucus spiralis (Sacchi, 1969 in Reid, 1996). On exposed shores, usually, the aperture is larger and the shell thinner than in other situations, and may resemble L. obtusata s.s.
The shells above have relatively large apertures and thin shells. The domed protruding spires of 1, 7 & 8 resemble many adult L. obtusata s.s. while 3,4,5 & 6 have almost flat spires found on juveniles of both species.
Cliffs near Aberdeen, Scotland. 1971.
Full account at: 02 Differentiation L. obtusata/L. fabalis

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