The DNA barcode (COI-5P) was used to investigate cryptic diversity among
Rhodymenia spp. in southern Australia. Whereas eight species are currently recognized, we uncovered ca. 20 genetic species groups, phylogenetically assigned to four genera in two families. Procumbent specimens with molecular and anatomical signatures of the Fryeellaceae are assigned to
Pseudohalopeltis tasmanensis gen. et sp. nov. Collections from Lord Howe Island recorded in the field as
Rhodymenia/Fauchea sp. are assigned to the poorly known genus
Microphyllum as
Microphyllum robustum sp. nov. A cluster of species with distinct molecular and anatomical attributes is included in a resurrected
Halopeltis J.G. Agardh, including
Halopeltis australis (J. Agardh) comb. nov. (type species);
Halopeltis austrina (Womersley) comb. nov.;
Halopeltis cuneata (Harvey) comb. nov. [including
Rhodymenia halymenioides (J. Agardh) Womersley];
Halopeltis gracilis sp. nov.;
Halopeltis prostrata sp. nov.; and
Halopeltis verrucosa (Womersley) comb. nov. Four additional species of
Halopeltis from Lord Howe Island (LH1, LH2), Tasmania (TAS), and Western Australia are not characterized further. For
Rhodymenia sensu stricto, similar levels of cryptic diversity were noted. Samples tentatively field-identified as ‘‘
Rhodymenia sonderi,’’ but having affiliations to
Rhodymenia rather than
Halopeltis, are referred to
Rhodymenia novahollandica sp. nov. Collections field-identified as
R. obtusa are genetically distinct from that species and are assigned to
Rhodymenia wilsonis (Sonder) comb. nov. Two highly divergent species currently identified as
Rhodymenia leptophylla (LH from Lord Howe Island; TAS from Tasmania), as well as two additional cryptic previously unnamed taxa from South Australia (SA) and Victoria (VIC), are not characterized further.