C. sp. 'Lingga 7' leaves had distinct red main vein and had spathe with yellowish limb and reddish throat, see his blog for the photographs of the spathe. My friend termed it as "red line". They were growing submersed in a sandy stream with water pH of about 5.0. They were many harlequin rasboras in the stream.
We found an unopened spathe which unfortunately did not bloom before melting away.