How do South American lungfish nests differ from African lungfish nests?

The nesting habits of African and South American lungfish differ significantly in their structural design:

• African lungfish: These fish construct their nests as simple pits located on the bottom of a watercourse.1
• South American lungfish: These fish dig nests that take the form of a vertical passage, which often turns horizontally at the bottom.1

In both species, the male remains in the nest to guard the brood. However, the South American lungfish male exhibits a unique adaptation during the spawning season: his pelvic fins develop vascularized, tuft-shaped growths that are believed to release oxygen into the water to support the developing young.1