Several of these nominal taxa have been treated as separate species and at least B. difficillimus may indeed prove to be a separate species. Until more evidence to the contrary is available from critical studies of patterns of variation, I shall treat them as parts of a single variable species. Oriental, Palaearctic Regions.
More evidence is awaited.
I have seen no males of this species and its precise relationships remain unclear. This convention has since changed and recent authors have consistently used s . No type specimen is known. If B. saltuum were accepted as most likely to be conspecific with B. subterraneus , then no further action would be required. Alternatively, if B. saltuum were considered more likely to be conspecific with B. barbutellus , then B. saltuum would become the oldest available name for that species, even though the name has not been used in the last 50 years.