We do not see evidence for the presence of female gametangia (oospores) in North American Nitellopsis obtusa (Desvaux) J. Groves

Abstract

We contest the recently reported findings that suggest the presence of female gametangia in the North American range of the invasive macroalga Nitellopsis obtusa (Harrow-Lyle, T.J., Ginn, B.K., Kirkwood, A.E., and Melles, S.J. 2023. First report of female gametangia in the invasive macroalga starry stonewort (Nitellopsis obtusa) in North America. Botany, 101: 61–64. doi:10.1139/cjb-2022-0096). The claims do not clearly show identifying morphology of N. obtusa female gametangia, are inconsistent with known characeaen developmental biology, and do not provide the evidence commensurate with such a claim. More convincing observational data are required. To date, only male thalli of N. obtusa have been confirmed either with herbarium vouchers or clear images. The appearance of female gametangia would have significant implications for the invasion biology of N. obtusa as well as approaches to managing its spread.