Isoëtes santacruzensis J.B.S.Pereira, PhytoKeys 131: 61. 2019.

Range:— Endemic to eastern lowland Bolivia (SC).

Ecology:— So far known only from two sites in seasonal pools on exposed surface rock of granite bedrock outcropping within a matrix of seasonally dry forest and cerrado habitats; 450 m.

Notes:— Besides the characters mentioned in the key, I. santacruzensis is characterized by its erect, conspicuously flexuous leaves.