Several species of Malagasy Euphorbia are described and compared to related species in their respective sections, along with identification keys for morphologically close relatives and distribution maps: Euphorbia agatheae, Euphorbia atimovatae, Euphorbia fuscoclada, Euphorbia graciliramulosa, Euphorbia kalambatitrensis, Euphorbia linguiformis, Euphorbia mahaboana, Euphorbia makayensis, Euphorbia multibrachiata, Euphorbia parvimedusae, Euphorbia perrierioides, Euphorbia rigidispina, Euphorbia spannringii, Euphorbia tsihombensis. New synonyms and new combinations and statuses are proposed, such as Euphorbia antsingiensis and Euphorbia crassa, and a lectotype is selected for Euphorbia rangovalensis.