On Two Species of Kallymenia (Rhodophyta: Gigartinales: Kallymeniaceae) from the Hawaiian Islands, Central Pacific

Two species of Kallymenia from the Hawaiian Islands, one rare, K. sessilis Okamura, and the other described here for the first time, K. thompsonii, n. sp., are examined, compared, and contrasted with other similar Kallymenia species. Both species are unusual because Kallymenia is generally regarded as a temperate taxon, and tropical or subtropical species are seldom encountered. The two species are alike in that they have a female reproductive apparatus that is monocarpogonial: wherein a single carpogonial filament is associated with a supporting cell also bearing an arrangement of subsidiary cells that is characteristic of some of the family Kallymeniaceae. In the genus Kallymenia, vegetative components shown in a cross section are a narrow outer cortex, often only three cells thick, followed inwardly by one to two layers of subcortical cells. In the two species studied here, there appears to be a constant shape and arrangement of subcortical cells in each species, whereas the number of medullary filaments and their arrangements appear to be less stable in their configuration than the subcortical cells. Branched refractive cells or stellate cells, which often occur in species of Kallymenia, were not seen in K. thompsonii and only rarely in K. sessilis. Kallymenia thompsonii commonly has perforations in the maturing blades, whereas K. sessilis does not.