get the species list (spp) for a given genus

Hello, I am a beginner in R. 

I am having trouble getting the list of species (spp) for a particular genus. 

spp <- BIEN_occurrence_genus("Aeschynomene", only.new.world = T)

Following error appears. 

Error in .BIEN_sql(query, ...) : unused argument (only.new.world = TRUE)

Please, can you help me?


