This name is a synonym of Ptelea trifoliata f. pubescens (Pursh) Fernald.
The record derives from Tropicos
(data supplied on 2012-04-18)
which reports it as a synonym (record 50088838) with original publication details: Fl. Amer. Sept. 1: 107 1814.
Full publication details for this name can be found in IPNI: http://ipni.org/urn:lsid:ipni.org:names:213735-2.
This name was in version 1 of The Plant List, record tro-50088838, and has not been changed.