Two new species of Caloglossa (Delesseriaceae, Rhodophyta) from the Americas, C. confusa and C. fluviatilis spp. nov.

Although the systematics of Caloglossa has been intensely investigated, the species diversity of the genus is not yet fully understood. Comparative chloroplast-encoded rbcL and nuclear LSU rDNA sequence analyses, combined with morphological observations, reveal new records and two new species for the Americas. The species, previously identified as Caloglossa monosticha from the western Atlantic, is newly described as C confusa sp. nov. It differs from Pacific Ocean C monosticha primarily by its strongly constricted thallus nodes, and the sequence data presented here show that it is most closely allied with other taxa of the C. continua species complex, but its relationship with these taxa is not fully resolved. The freshwater C. fluviatilis sp. nov. from the Panama Canal is characterised by thalli arranged in tufts, adventitious branching, strong constrictions at the thallus nodes and lanceolate blades. Caloglossa fluviatilis forms a monophyletic group along with the species having only adventitious secondary branching. A dichotomous key highlights the diagnostic vegetative characters for separating the nine species of Caloglossa occurring in the Americas.