Emarginula costulata Deshayes, 1863: 47, pl. 7 [34], figs 3–5. Thiele, 1915 in 1912–1919: 79, pl. 9, fig. 22 (further references). Viader, 1937: 57. Drivas & Jay, 1985: 5, fig. 9. Drivas & Jay, 1988: 32, pl. 1, fig. 4 (not 3 as indicated). Herbert, 1987 b: 11, figs 39–42. Singer, 1998: 5. Type loc.: Réunion; lectotype in MNHN, designated by Herbert (1987 b: 11). Emarginula tenuicostata (non G.B. Sowerby (II), 1863)— Kilburn, 1978: 442, pl. 4 c, d, g. Herbert & Kilburn, 1986: 11, fig. 37.
Distribution. South-western Indian Ocean; Mauritius, Réunion and Mozambique, south to northern Zululand (off Dog Point); shallow subtidal to 100 m (living 5–70 m).
Notes. Melvill & Standen (1898) recorded this species from the Madras area, India, with ‘some slight doubt’ regarding the identity of the material.