The orchid naming is full of confusion, especially with the names being updated so frequently.
OK. Here is the catch. The Dendrobium aphyllum that you searched is not Dendrobium pierardii, but really Dendrobium aphyllum (Roxb.), which is also called as Dendrobium macrostachyum! When you search for Dendrobium aphyllum, you get to see 3 entries:
Dendrobium aphyllum (Roxb.) C.E.C.Fisch. in J.S.Gamble, Fl. Madras: 1416 (1928).
Dendrobium aphyllum var. cucullatum (R.Br.) P.K.Sarkar, J. Econ. Taxon. Bot. 5: 1007 (1984).
Dendrobium aphyllum var. katakianum I.Barua, Orchid Fl. Kamrup Distr. Assam: 170 (2001).
Click on the last 2 and you will see that they take you to the page where they say the current name is Dendrobium cucullatum! The first one is a different species as give by its synonym Dendrobium macrostachyum. You can try searching for the last name and it will take you to Dend aphyllum (Roxb.)!
You can look at the below IOSPE link as well for Dend aphyllum (Roxb.)
IOSPE PHOTOS