Naturally occurring Cryptocoryne hybrids were a bit of a puzzle until modern methods revealed many "species" that were known for a long time were in fact naturally occurring hybrids a phenomenon not unique to just the plants, in the same era it was learned that all Rift lake cichlids were also all hybrids.
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.
Suwidji Wongso writes:
"During trip with Hendra Budianto in 2003, we collected a few specimens of an interesting plant in the C. striolata habitat at Loksado, Mount Besar which I suspected to be natural hybrid between C. striolata and C. hudoroi. I cultures it and later it bloomed in my place.
Fifteen years later it was finally confirmed and is indeed a natural hybrid between C. striolata and C. hudoroi.
Unfortunately the collction spot has been cleared shortly after our visit and further collections there proved just to be striolata.
When my previous system broken down in 2009, I sent it to Jan Bastmeijer who reports it is thriving and propagating very well in Europe and I was fortunate enough to get a plant from Niels Jacobsen in 2014.
Long story short, we named it C. x hendrae.
It has intermediate form of leaf and spathe of its parents and develop runners like hudoroi.
The "old aquarium nevillii" is really wilissii - and are naturally occuring hybrids. There are many forms of this plant, for example the old "C. lucens" - this is not a sepcies, just another form of WIL.