I should start by correcting my OP. I started with DEMULTIPLEXED sequences, not dereplicated sequences.
To import, I used the code:
qiime tools import --type 'SequenceData[Sequences]' --input-path Hines_SeqData_Final.fasta --output-path Hines_RepSeqs.qza
Yes, I used q2-vsearch to dereplicate the sequences after import, but not before following the q2-ghost-tree community tutorial guidelines for importing & rooting a pre-built tree, downloading the UNITE database, clustering my sequences into 99% OTUs, & created artifacts for my OTU table.
qiime vsearch dereplicate-sequences \
--i-sequences Hines_Seqs.qza \
--o-dereplicated-table Hines_table.qza \
--o-dereplicated-sequences Hines_rep-seqs.qza
qiime vsearch cluster-features-closed-reference \
--i-table Hines_table.qza \
--i-sequences Hines_RepSeqs.qza \
--i-reference-sequences sh_refs_qiime_ver7_99_01.12.2017_dev.qza \
--p-perc-identity 0.99 \
--o-clustered-table Hines_table_99.qza \
--o-clustered-sequences Hines_RepSeqs_99.qza \
--o-unmatched-sequences Hines_unmatched_99.qza
I then used the q2-diversity plugin to create that specific table using commands from this post.:
qiime diversity alpha \
--i-table Hines_table_99.qza \
--p-metric observed_otus \
--o-alpha-diversity Hines_observed_otus_vector.qza