Key to the species of Strigoderma costulipennis species group (modified from Bader 1992)

1 Pronotum coarsely punctate; elytral ridges rounded and shallow................................... S. tomentosa Bates

- Pronotum with fine and dense punctation; elytra with acute elevated ridges....................................... 2

2 Males with the inner proclaw shorter than the protarsomere 5, and with the inner ramus 0.7 of the length of outer ramus (Fig. 4); male genitalia as in Figs. 5–6; length 5–7 mm ........................................... S. costulipennis Bates

- Males with the inner proclaw as long as the protarsomere 5, and with the inner ramus 0.3 of the length of outer ramus (Fig. 1); male genitalia as in Figs. 2–3; length> 7 mm ................................. S. tenebrosa Delgado & Mora-Aguilar