<i>Roseolithon mirabile</i> (Foslie) comb. nov. (Hapalidiales, Corallinophycidae, Rhodophyta) based on DNA sequencing of the <i>Archaeolithothamnion mirabile</i> lectotype

Abstract Lithothamnion mirabile is currently considered a heterotypic synonym of L. muelleri. Three of the 14 specimens and additional fragments comprising the holotype of L. mirabile were selected for DNA sequencing as they best matched the protologue. The three 263-base pair rbc L sequences were distinct from each other, and were classified in the order Hapalidiales, but none were resolved in Lithothamnion. One sequenced specimen belongs in Roseolithon and was selected as the lectotype; thus we propose R. mirabile (Foslie) comb. nov . Another sequenced specimen groups with Phymatolithopsis and the third is well resolved in an undescribed genus of Hapalidiales sister to Boreolithothamnion .