Filament of penis folded forward at 1.
2: non-mucronate tip of penis. Explanation of “mucronate” at eflora.library.usyd.edu.au/glossary/mucronate

Wide grey dorso-lateral bands on cephlic tentacles separated by narrow medial yellowish line. Dark head and snout with yellowish snout-tip. Eye on broad unpigmented base of tentacle.

Other identification criteria used for specimen P
Previous work by Hannaford Ellis on the same shore as this find showed that L. arcana were thin-shelled, heavily ridged and multicoloured with tessellations or bands. The shell of this specimen fits the description. In contrast, L.saxatilis s.s. had thick smooth unicolorous shells. N.B. these shell differences only apply on this shore; neighbouring shores had different shell characteristics that did not enable segregation of the spp. See P8535

Dissection showed no patch-like ciliated field between anus and head (as often found on L. saxatilis s.s.) but there was a suggestion of a linear pink ciliated field running next to the edge of the pink prostate (as appropriate for L. arcana).

L. compressa occurs on the same shore but can be eliminated from consideration as the shell is over 6mm high and lacks broad, flat-topped or gently curved, strap-like, spiral ribs with narrow, deeply incised grooves.

No full account yet of this species.
marinvert.senckenberg.science/image-browse/7215763361…