If you compare the start of your sequences to the Illumina adapter/primer sequences, you will see they match in the second-half:
CCTACGGG
TCGTCGGCAGCGTCAGATGTGTATAAGAGACAGCCTACGGGNGGCWGCAG
NACTAC
GTCTCGTGGGCTCGGAGATGTGTATAAGAGACAGGACTACHVGGGTATCTAATCC
Those are the 341F and 805R primers, and they need to be removed. You can do so here with trim-left-f 17 and trim-left-r 21, which you can read off the above.
This amplicon is longer than the reads, so they won't read into the other primer, hence trunc-len is not needed for primer removal.