Herbert, I learnt here in the past ... it depends whom you will follow.
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'Die Orchidee' Vol. 3(06)2017 lists 3 varieties of P. gratrixianum ... var. gratrixianum, var. christensonianum and P. sulivongii ...... Paph. daoense is listed there as true species.
- KEW Science lists
Paph. gratrixianum as a species with 3 varieties ... var. gratrixianum, var. daoense and var. guangdongense. There are photos of P. gratrixianum and I personally can't see that they resemble or match to P. insigne a lot. ..... Paph. christensonianum is there listed as true species.
-O.Gruss in 'Paphiopedilum Südostasiatische Frauenschuhe' Band 2/volume 2 accepts Paph gratrixianum with one fma. galherianum, and the varieties. ... var. cangyaense and var. guangdongense. Paph. christensonianum and Paph. daoense are listed as true species.