1906 Monterrey specimen C. G. Pringle 10169 (US) is Chaptalia carduacea

by Bob Harms 

Thanks to a loan of Chaptalia specimens from the U.S. Herbarium one Mexican Chaptalia carduacea was found:

Nuevo León: Shaded banks of the Sierra Madre above Monterrey, 2—3000 ft., 2 April 1906,
C. G. Pringle 10169 (US)

Click specimen images for enlargements.

A duplicate specimen, C. G. Pringle 10169 (LL), was C. texana, but bear in mind that at that time these two species were both considered to be C. nutans. (And mixed collections from Pringle are not unheard of.)