Where Are We Now Regarding Hawaiian Stream Algal Systematics? (A Suspiciously Cosmopolitan Flora)

The last decade has witnessed a great advancement in our understanding of the Hawaiian stream algal flora. Several large surveys have produced comprehensive data sets for the four largest main Hawaiian islands (Kaua‘i, O‘ahu, Maui, and Hawai‘i), which have resulted in a substantial increase of recorded taxa for the state. A compiled checklist is presented for the stream algal flora of Hawai‘i, which includes 174 taxa. Overall, the Hawaiian stream algal flora is estimated to be only 2.3 % endem-ic, which is very low compared to other groups of organisms in the state. The major drawback of most stream algal studies to date has been the reliance upon morphology-based identification techniques. As a result, most Hawaiian stream algal collections have had taxonomic names “force fit ” to them from floras based on other geographical regions around the world. This has led to the recognition of a largely cosmopolitan Hawaiian stream algal flora with a very low rate of endemism, compared to other groups of organisms. Although it is recognized that the stream algal flora may indeed be more cosmopolitan than other groups of organisms in Hawai‘i due to its high dispersal capability, the cur-rent estimate is regarded as suspiciously high. Artificial deflation of the degree of endemism may have arisen from a combination of “force-fitting ” names from other regional floras, a reliance on morpho-logical characters for identification, and a lack of taxonomic expertise. Estimates of the degree of endemism in the Hawaiian stream algal flora will likely increase with the inclusion of molecular- and genome-based characters in future taxonomic studies