There are many spines on each areole, the central ones up to 4.4 cm (1.7 in) long.

The spines are purple, pink, or white with brown tips.

The flower is up to 6 cm (2.4 in) long by 9 cm (3.5 in) wide and has white, pink, or lavender tepals with greenish, brown, or reddish coloration at the bases.

acunensis is not easily distinguished from S. johnsonii subsp.

erectocentrus using morphological characteristics, but they occur in different geographical areas.