This name is a synonym of Euphorbia deltoidea subsp. pinetorum (Small) Oudejans.
The record derives from WCSP
(data supplied on 2012-03-23)
which reports it as a synonym (record 38172) with original publication details: Bull. New York Bot. Gard. 3: 429 1905.
Full publication details for this name can be found in IPNI: http://ipni.org/urn:lsid:ipni.org:names:308665-2.
This name was in version 1 of The Plant List, record kew-38172, and has not been changed.