Succulent <i>Euphorbia costatoalata</i> sp. nov. (Euphorbiaceae) from southern India

Euphorbia costatoalata sp. nov. is allied to Euphorbia tortilis but differs from the latter in having prominent ribbing and up to five wings; segments longer, thinner, usually not in a spiral; cymes fewer per axil; glands trapezoidal, humped convexly upwards; ovaries flattened with non‐connate styles; capsules concave on top; and seeds dark brown with light speckles and streaks. This species appears to replace E. tortilis north of the Nilgiri and Biligirirangan hill ranges.