Proposal of Cryptonemia floridana comb. nov. (Halymeniaceae, Rhodophyta) based on rbcL gene analysis of collections from type locality and female reproductive morphology

The taxonomic position of Halymenia floridana is a long-standing issue that needed to be assessed using DNA sequences of material from the type locality (Florida, USA). Here, we examined the vegetative and reproductive morpho-anatomy, and rbcL sequence data of topotypes and additional specimens from Brazil. Our results resolved the topotypes of ‘H. floridana’ within the genus Cryptonemia, in a clade harboring two closely related sister species, C. bermudensis and C. lacunicola. The rbcL haplotype of ‘H. floridana’ from Florida was also identical to previously and newly sequenced specimens from Brazil. Therefore, the new combination Cryptonemia floridana comb. nov. is herein established. Cryptonemia floridana exhibits entire to lobed foliose blades up to 12 cm high, a short basal midrib, medulla with conspicuous stellate ganglia and mostly periclinal filaments. The auxiliary cell is the first or the second cell of a third-order ampullar filament, and secondary connecting filaments are rare and cut off from the fusion cell. Our study is the first to provide the pre- and postfertilization stages in a Cryptonemia species, with generic status confirmed by DNA sequences. Numerous tropical Cryptonemia species await molecular confirmation and assessment of reproductive structures towards a better circumscription of the genus and its species diversity.