Specimens of L. obtusata (det. by penes) found together on Ascophyllum nodosum on sheltered shore.
1: receptacle (reproductive body containing male and female gametes) of Ascophyllum.
2: receptacle grazed by L. obtusata.
3: air vesicle (bladder) of Ascophyllum nodosum.
4: half grown olivacea specimen, shade matches that of Ascophyllum nodosum when in water, as in this image.
5: fusca colour form, shade matches that of Ascophyllum nodosum when dry. Purple or brownish shell interior is frequent on L. obtusata.
6: olivacea specimen with some green alga on it, shade fairly close to that of receptacle.
7: citrina colour form, also on virtually all L. fabalis on Fucus serratus on the same shore, but this specimen is much larger than any of the L. fabalis which are of a small form here.
8: citrina juvenile L. obtusata is same size as adult citrina L. fabalis on Fucus serratus on the same shore, but distinguished as found on Ascophyllum with adult L. obtusata and it has juvenile thin, spouted lip that doesn’t constrict aperture, while adult L. fabalis on this shore have thick lips and constricted aperture.
Menai Strait, North Wales. February 2011.
Full account at: 02 Differentiation L. obtusata/L. fabalis
19 Differentiation L. obtusata/L. fabalis
