Clarifications about the identity of the names Sagina alexandrae and S. hawainensis (Caryophyllaceae)

The names Sagina alexandrae and S. hawaiensis are currently considered heterotypic synonyms. A detailed analysis of the protologues and other pertinent literature, as well as the study of the original material and other specimens, reveals that these two names do not represent the same taxon. Based on Pax’s original description and Hillebrand’s linked account published in Flora of the Hawaiian Islands, we noted that S. hawaiensis was described as having petals half as long as the sepals (“petalis quam calyx dimidio brevioribus” in the protologue), whereas the petals of S. alexandrae are longer than the sepals. Notably, S. hawaiensis was described with an uncommon combination of characters, specifically regarding the flowers which are 5-merous, with corollas shorter than the calyx, and 10 stamens. Among the few Sagina taxa with 10 stamens (S. caespitosa, S. maxima, S. nivalis, S. nodosa, and S. saginoides), only S. maxima s.s. exhibits a morphology matching that of S. hawaiensis. The nomenclature of these two names is clarified as follows. According to Arts. 9.3, 9.6, and 9.10 of the Madrid Code, the indication of “holotype” by Crow for S. maxima is corrected to “lectotype” (specimen at GH). Lacking any original material for S. hawaiensis, as well as useful specimens collected in Hawaii, the type of S. maxima was designated as the neotype (Art. 9.8) of S. hawaiensis, thus making the two names homotypic (new synonymy).