Rare Piper species, for the collector-type. You'll receive a similar sized curring, grower's choice

With that said, it's actually proven fairly easy. Airflow, Promix HP potting media, clean distilled water, light fertilization. Probably needs on the higher end of the humidity spectrum, and definitely does well in such conditions. Anything under 70%RH is possible but experimental.

Looks very similar to the 'aff crypantha' (odd trade name, I don't know) but has distinction in appearance on development of mature foliage.