Pleopodal lungs

Pleopodal lungs are an anatomical feature of terrestrial isopods and a component of their respiratory system.

They are ancestrally derived from pleopodal gills, and they facilitate gas exchange on land.

They perform a function similar to spiracles in insects.

[1][2] Pleopodal lungs are identifiable on woodlice as white patches on the lower five segments (the pleon) on the ventral side (underside).

The number of pleopodal lungs varies by species: they may have up to five pairs, or only two pairs as in Porcellio laevis; a minority of species lack pleopodal lungs entirely.

The white patches on the first two pairs of pleopods on this specimen of Porcellio laevis identify them as pleopodal lungs.
Armadillidium vulgare , male pleon, ventral view.
en endopodite
ep epimeron
ex exopodite
lg pleopodal lung
pp pleopod
pr protopodite
pt pleotelson
ur uropod
Pleopodal lungs of Porcellio scaber