Mitchell, M 2010, 'Actiniaria (Cnidaria: Anthozoa) of Port Phillip Bay, Victoria : including a taxonomic case study of Oulactis muscosa and Oulactis mcmurrichi', MSc thesis, Southern Cross University, Lismore, NSW.
Copyright M Mitchell 2010
This study is the first dedicated survey cataloguing the actiniarian fauna of Port Phillip Bay, Victoria, Australia. There is a paucity of knowledge of Australian Actiniaria (true sea anemones) fauna. Therefore, Australian marine fauna surveys and most field guide books identify many sea anemones only to genus, if they are identified at all. Much of the knowledge of Australian actiniarian fauna is based upon preserved specimens, resulting from broad scale surveys, and sent to overseas actiniarian specialists for identification and description, and most species lack information on important in-vivo characteristics.
Surveys of Actiniaria fauna were conducted in new, and previously surveyed areas, of Port Phillip Bay. In addition, preserved Port Phillip Bay Actiniaria specimens housed in Museum Victoria, were examined to verify previous species identifications. Sixteen Actiniaria species, including Oulactis muscosa, are documented for Port Phillip Bay. In addition, four potentially new actiniarian species, that could not be verified during this study, were recorded.
Actiniarian taxonomy is a complex discipline, and problems of species identifications are exacerbated because important in-vivo characteristics are lost during the preservation process. In addition, poorly preserved material and lack of detailed information on characteristics of living actiniarians has meant that important data needed for distinguishing species is often absent. Therefore cryptic species and information on intraspecific regional variation of species is usually lacking.
Oulactis muscosa and Oulactis mcmurrichi are two morphologically similar actiniarian species that need taxonomic re-evaluation Taxonomic keys for southern actiniarian fauna do not distinguish between the two species because of their similarity in appearance; and it may be the case that they constitute a single species. Accordingly, a taxonomic case study of the two Australian Oulactis species was conducted to determine if they should be synonymised. As genetics are increasingly being used in taxonomic studies, the use of ribosomal DNA as an aid in identifying actiniarian species was evaluated.
Oulactis muscosa and 0. mcmurrchi in-vivo characteristics were documented from Australia, New Zealand and Argentina. In addition, morphological characteristics of Oulactis specimens from Australian Museums were documented together with newly collected specimens from Australia and New Zealand. The results from this study indicate that Oulactis muscosa and Oulactis mcmurrichi should remain as two separate species. Important in-vivo characteristics are critical to the identification of these species. The regional intraspecific variation of these species is considerable, and therefore it is possible that some of these morphological variants represent potentially new species of Oulactis.
Further analyses of these species and other actiniarians examined in this study that incorporate genetic analyses may provide additional valuable information for resolving the taxonomic status of actiniarian species in Australia. It was found that ribosomal DNA may aid in distinguishing cryptic species, intraspecific regional variations, and identify juveniles and adults that have differences in appearance. This study has provided some important baseline data for future work on Port Phillip Bay Actiniaria and Oulactis species in Australia and New Zealand.