Apistobranchus jasoni sp. nov. a example of juvenile (paratype, NHM.2018.12713) (left) and adult (holotype, NHM.2018.12712) (right) specimen in lateral view b transition between regions with (chaetigers 2–6 and 10 onwards) and without (chaetigers 7–10) acicular branchiae-like lobes (abrl) c specimen with Methyl Green stain pattern d SEM micrographs of anterior region in dorsal view e SEM micrographs of capillary chaetae. Scale bars: 1 mm (a); 500 µm (d); 100 µm (e).