How To Count Genes In Genomic Regions Using A Gtf/Gff3 And A Bed File Of Regions

I'd like to count the number of unique genes in a gff file falling within a list of genomic regions. With bedtools I can count the number of regions within the gff which is almost what I want, but not quite.

bedtools intersect -a regions.bed -b my.gff -c

UPDATE:

I should have made my question a bit more specific. I have a modified ensemble style gtf file (not a gff) that has unique transcript IDs. This means that simply selecting unique fields in the 9th column of the gtf file actually counts transcript IDs.

To circumvent this problem I first truncated the gtf file:

cat my.gff | sed -e 's/;.*//' > delete.me.gtf

Then I ran the bedtools map command:

bedtools map -a regions.bed -b delete.me.gtf -c 9 -o count_distinct > counts.genes_in_windows.bed

I almost forgot to delete the intermediate file:

rm delete.me.gtf

There is probably a way to make this a oneliner, without the intermediate file, but I have a dissertation to write!