In 2004 Isa Ipor found an unknown Cryptocoryne in Western Sarawak that looked somewhat like C.×purpurea nothovar. purpurea from the Malay peninsula and gave it the working name "nothovar. sarawacensis" but proved to be a natural hybrid between C. cordata var. cordata and C. griffithii and is fully sterile. As var. cordata does not grow in Borneo at all, the close related C. cordata var. grabowskii could replace, but C. griffithii is only known from southern Borneo and is not reported from Sarawak.
It was later found to be a hybrid between C. cordata var. grabowskii and C. ferruginea var. ferruginea who published their results in 2015.