Haplophthalmus danicus, also known as the terrestrial cave isopod or spurred ridgeback isopod, is a species of woodlouse in the family Trichoniscidae.

It is naturally found in Europe, Southern Asia, and temperate Asia, however it has been introduced to North America.

[1][2][3][4] This species was likely introduced during original European settlement, and therefore has been well established in terrestrial communities.

[5] These seven subspecies belong to the species Haplophthalmus danicus:

This isopod-related article is a stub.