DNA-based identification of fern gametophytes from two different species of Hymenophyllum in Aotearoa New Zealand

Despite being a critical phase of the fern life cycle, gametophytes are often overlooked. However, the characterisation of fern gametophytes is being revolutionised by the ability to make identifications using DNA sequencing. Here, in a first for Aotearoa New Zealand, we use DNA sequencing to identify two fern gametophyte collections. Both have a branching, ribbon-like morphology, unlike the cordiform morphology of most fern gametophytes and were identified in the field as thalloid liverworts. DNA sequencing revealed both to be species of Hymenophyllum endemic to New Zealand: H. demissum and H. revolutum . There are few collections in New Zealand’s herbaria focused on fern gametophytes, making these valuable additions. We call for greater investigation and documentation of fern gametophytes in New Zealand and raise the possibility that unrecorded species may be present as gametophyte-only populations as has been found elsewhere in the world.