Collection information for the specimens used in this study.

USNM# is the catalog number for the specimen at the Smithsonian Institution. Dive numbers are abbreviated by vehicle – AD- Alvin Dive, P5– Pisces 5, T – Tiburon, JD – Jason II Dive. Haplotypes for each marker are number coded, with each number indicating a unique sequence for a given marker. Variable positions among haplotypes of Narella for each marker are given in Supplemental Table 2.‘– specimen depth not recorded, values given are for depth range for dive, or specimens collected before and after that individual.*indicates a specimens which was sequenced more than once, with identical sequences encountered every time.