To my knowledge the subgenus Sinistrella is based only on direction of
coiling. If I am correct in this, as sinistrality/dextrality is of no
taxonomic standing, there is no basis for using the name, making it an
outright synonym of Fusinus.

Remember, if coiling direction was a taxonomic character, a sinistral
specimen of say Amphidromus cambojiensis would be in a different subgenus
or genus to a dextral specimen of the same species. This of course is
ridiculous.

The various species ascribed to Sinistralia do not appear to be closely
related to one another. The species probably belong to several other
subgenera. This would make Sinistralia as currently used paraphyletic.

Harry, can you suggest any literature on the group?

Andrew