Abstract
[The final version of this article may be found here]
The mitochondrial gene cytochrome-c-oxidase subunit 1 (COI ) is
useful in many taxa for phylogenetics, population genetics,
metabarcoding, and rapid species identifications. However, the phylum
Ctenophora (comb jellies) has historically been difficult to study due
to divergent mitochondrial sequences and the corresponding inability to
amplify COI with degenerate and standard COI ‘barcoding’
primers. As a result, there are very few COI sequences available
for ctenophores, despite over 200 described species in the phylum. Here,
we designed new primers and amplified the COI fragment from
members of all major groups of ctenophores, including many undescribed
species. Phylogenetic analyses of the resulting COI sequences
revealed high diversity within many groups that was not evident from
more conserved 18S rDNA sequences, in particular among the
Lobata. The COI phylogenetic results also revealed unexpected
community structure within the genus Bolinopsis, suggested new
species within the genus Bathocyroe , and supported the ecological
and morphological differences of some species such as Lampocteis
cruentiventer and similar undescribed lobates (Lampocteis sp.
‘V’ stratified by depth, and ‘A’ differentiated by color). The newly
designed primers reported herein provide important tools to enable
researchers to illuminate the diversity of ctenophores worldwide via
quick molecular identifications, improve the ability to analyze
environmental DNA by improving reference libraries and amplifications,
and enable a new breadth of population genetic studies.