Abstract
The Shenzhen Code (Turland & al. in Regnum Veg. 159. 2018) says nothing about the use of an adverb as a specific or infraspecific epithet, but it would appear to be covered by Art. 23.1 (“a word in apposition”). Because it is not an adjective, an adverb should be treated as a word in apposition and therefore would not change its form according to the gender of the generic name.
The epithet in the name Caladenia postea Hopper & A.P. Br. (in Nuytsia 14: 268. 2001) is from the adverb postea, afterwards, referring to the flowering time compared with related taxa. The ending appears to agree with the gender of the generic name, but this is coincidental. Should the species ever be moved to a genus of masculine or neuter gender, the spelling of the epithet would remain the same.
The final epithet in the name Ptilotus polakii subsp. juxta Lally (in Nuytsia 19: 61. 2009), although published as ‘juxtus’, is from the adverb juxta, next to, close by. This is an adverb and hence the ending may not be changed. The spelling is correctable to juxta.
It would be useful to include mention of the use of an adverb in the Code...