Female L. obtusata.
Goodwin & Fish (1977) wrote that the colour of the female’s ovipositor is “to varying degrees black pigmented” on L. obtusata, while that on L. fabalis “lacks pigmentation” in 99% of cases in Wales. Reid (1996) stated that it is not so in all areas.
This specimen has an ovipositor that is pigmentless at the posterior (1) shading forwards through yellow and orange to dark brown at the anterior (2), so fits neither description precisely. It is closest to that of L. obtusata, and as the shell size, form and colour matched that of males of that species (penes checked) found with it on the same patch of Ascophyllum, and, on this sheltered beach, the L. fabalis on Fucus serratus were of the most distinctly different shell form and size, there is no doubt that this female is L. obtusata.
Shell height 12.6 mm. Menai Strait, North Wales. September 2016.
Full account at: 02 Differentiation L. obtusata/L. fabalis

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