SKELETAL CARBONATE MINERALOGY OF BRYOZOANS FROM CHILE: AN INDEPENDENT CHECK OF PHYLOGENETIC PATTERNS

Bryozoa exhibit some broad phylogenetic patterns in skeletal carbonate mineralogy that have previously been elucidated based on material from Australasia, Europe, North America, South Africa, and Antarctica. A new dataset from 19 locations in the Patagonian fiord region of Chile adds 93 specimens and 23 species to the mineralogical information on this highly variable phylum, as well as providing a comparison with generalizations made to date. Most species, genera, and families from Chile are of similar mineralogy to their worldwide counterparts, but a few are surprising. Chilean Membranipora isabellana and Diastopora sp. are both 100% aragonite despite belonging to taxa that are dominantly calcitic. Adeonella patagonica and Adeonella sp. are the only species exhibiting bimineral skeletons, from 6 to 100% calcite, a much greater range than was previously known for this genus and the Adeonellidae. Skeletal mineralogy has been tested in only 95 of the 323 families in the Bryozoa. We are, nevertheless, able to make some generalizations. For example, stenolaemates are almost always low-Mg calcite, and ascophoran cheilostomes are the most variable and mineralogically complex group. The capacity to generalize about bryozoan mineralogy is necessary in the face of increasing pressure on biomineralization from ocean acidification.