It is currently NULL , which does not return names.
> ex_taxmap$subtaxa(subset = is_root)
$b
[1] 3 7 12 8 13 4 9 14 5 10 15
$c
[1] 6 11 16 17
> ex_taxmap$subtaxa(subset = is_root, value = "taxon_indexes")
$b
d h m i n e j o f k p
3 7 12 8 13 4 9 14 5 10 15
$c
g l q r
6 11 16 17
It is currently
NULL
, which does not return names.