Plants tiny, usually unbranched in the wild, nearly covered by soil (often having only 2-5 areoles exposed). Stems erect, spheric, (1-)2-3 × 1-2(-2.5) cm; ribs 6-9, crests poorly defined, undulate; areoles of largest plants 6-7(-10) mm apart. Spines 8-14(-15) per areole, in relatively old plants curving irregularly in random directions, gray or white, some or all tipped black, dark reddish brown, or dull reddish purple; radial spines 8-14 per areole, ± pectinately arranged, (5-)10-15(-19) mm; central spines 0(-1) per areole, terete, 10-12 mm, closely resembling largest radial spines. Flowers 1.5-2 × 1.5-2(-2.7) cm; flower tube 5-8 × 5-10 mm; flower tube hairs very short, inconspicuous; inner tepals bright yellow-green, often with maroon midstripes, 9-18 × 2.7-3.8 mm, tips relatively thin and delicate; anthers yellow; nectar chamber 1 mm. Fruits purplish brown or remaining green when ripe, 5.5-9(-11) mm, pulp white. 2n = 22.
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