Caulerpa wysorii sp. nov., a denuded Caulerpa (Chlorophyta) resembling C. sertularioides when ‘dressed’

Routine DNA barcoding with the chloroplast gene tufA identified novel records of an unknown and denuded (i.e. lacking branchlets) Caulerpa species previously reported from the Florida Middle Grounds. tufA barcoding not only confirmed the matching molecular identity of this taxon with several newly collected denuded specimens from shallow habitats of the Yucatán shelf, but also with a set of plumose specimens previously collected from mesophotic depths of the West Florida shelf and recorded as Caulerpa sertularioides. Sequencing of two additional, faster-evolving DNA markers, i.e. nuclear ITS and the newly tested chloroplast-encoded rpoA, each confirmed conspecificity of the above morphotypes and the molecular separation of the new taxon from C. sertularioides and filiform species found in the region, namely C. cupressoides f. denudata and C. fastigiata. In light of our sequencing results and review of the early taxonomic history of filiform Caulerpa, we propose the description of Caulerpa wysorii sp. nov. for this new species that exhibits two distinct morphotypes in currently available collections, i.e. filiform or plumose assimilators. We also subsume C. tongaensis within the broadly distributed C. fastigiata, whose lectotype is also designated herein. In addition to Caulerpa wysorii sp. nov., we discovered yet another unknown denuded species from the Campeche Banks represented by a single specimen thus far.