shortest epithet

[Paul van Rijckevorsel]

Another contender, a genuine current species:

Bombacaceae Adansonia za Baill. 
in Bull. Soc. Linn. Par. 7. ii. (1890) 845 et Hist. pl. Madag. Atlas t. 79 C, 79D, 79 I. 

("za" or "zabe" being the local vernacular name of this tree)

PvR