it's a black calla :).
hard to say which variety: the underside is very bright pink with a bright rim - not sure if it's photo trick or they actually come this way consistently from corm.
may be blk forest or blk star or eclipse?

Here is a link that might be useful: see pics here

this pic is from macau flower exhibition dec 2012

Here is a link that might be useful: black calla original pic

looking at pics from this seller, it could be blk pearl too.

Here is a link that might be useful: more blk calla pics