Diodora octagona
NameDiodora octagona
Scientific NameDiodora octagona
Common NameOctagonal Keyhole Limpet
FamilyFissurellidae
GenusDiodora
Speciesoctagona
Geographic DistributionIndo-Pacific region, including areas such as the Philippines, Japan, and other parts of the Western Pacific.
Habitatintertidal
Shell Shapeconical
Average Size (mm)25
Identifying FeaturesDistinctive apical keyhole (foramen); strong, nodulose radial ribs, some of which are more prominent, giving an octagonal appearance to the shell margin; oval base; low conical profile.
Raritycommon
Author Citation(Reeve, 1850)
Description
A small, conical keyhole limpet shell, characterized by its oval base and prominent apical foramen (keyhole). The exterior surface is sculptured with strong radial ribs, some of which are more pronounced, giving the shell a somewhat octagonal outline, especially at the margin. These radial ribs are intersected by concentric growth lines, creating a nodulose or beaded texture. The shell is predominantly off-white to cream, often with scattered brownish or reddish-brown spots or blotches, particularly visible in the grooves and on the ribs. The interior is smooth, white, and reflects the external ribbing and the keyhole opening.
