Name and identification
Euphorbia costatoalata was described in a protologue released in 2025 and assigned to the journal volume for 2026. Its name refers to the ribbed stem wings. This account follows the original description. A separate record for the species in POWO was not independently confirmed when the database was checked on 21 October 2026 [De Jong et al. 2026] [2-WWW].
The plant forms a shrub or small tree 1.5–3 m tall. Its crown is spreading, open and irregular. Stems bear 3–5 wings, with conspicuous herringbone ribbing across the surfaces between them. Stem segments are usually straight or only slightly twisted. In E. tortilis, twisting is generally stronger and the crown more compact [De Jong et al. 2026].
Stems and small leaves
Branch segments are usually 10–20 cm long, occasionally reaching 40 cm, and 3–5 cm in diameter. Paired spines 3–4 mm long arise from shields along the wing margins. The tiny triangular leaves are approximately 1 mm long and wide and fall very early. Seedlings were described as mottled between the wings. Ribbing varied in prominence among populations, so identification also considers reproductive organs [De Jong et al. 2026].
Cyathia, fruits and seeds
A cyathium is a small inflorescence containing highly reduced flowers. In this species, its yellowish-green glands are oval to trapezoidal and distinctly convex in side view. The styles remain free from their bases. The three-lobed capsule measures about 7 × 4 mm, with rounded corners and a concave upper surface. Globose seeds approximately 2 × 2 mm are dark brown with paler streaks and speckles [De Jong et al. 2026].
The main flowering period at the reported localities extends from November to March. A smaller flowering flush was also observed from June to August. These dates describe the species in southern India and refer to its phenology in the region studied [De Jong et al. 2026].
Distribution and current knowledge
The species was described from rocky hillocks and outcrops of the southern Deccan Plateau, from Karnataka to Andhra Pradesh. The authors identified development on small hillocks as a threat to some localities and proposed Data Deficient, DD. This is the assessment made in the protologue. Its range and possible contact with E. tortilis require further field investigation. Potential hybridization between the species remains a research question [De Jong et al. 2026].
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