Cleistocactus sp.

Cleistocactus sp.
Date: 1999 June 22

I grew this plant from seed many years ago, and due to much neglect, it is still only about 20cm tall, with several branches, but in 1999 it flowered for the first time. Sometime during the intervening years, it had acquired the label Erdisia ayacuchensis, but the genus Erdisia should not have tubular flowers, and my plant looks like a classic Cleistocactus. Any suggestions as to which species would be most welcome!