How Did It Get Here? First Record of <i>Trochamminita irregularis</i> , a Cosmopolitan Estuarine Organic-Cemented Agglutinated Foraminifer, in South-West Western Australia

The cosmopolitan organic-cemented agglutinated foraminifer Trochamminita irregularis previously identified in Australian salt marshes of the Gippsland Lakes in Victoria and Little Swanport Estuary in Tasmania, has been recognised for the first time in Western Australia in the Hay River connected to Wilson Inlet, in the south-west of the State. The irregular test and chamber shapes may be related to the species mode of living restricted to the upper-marsh or river-margin environments in organic-rich sediment associated with filamentous rhizomes/stolons of marsh vegetation. Morphological variation may also be due to highly variable seasonal to daily environmental changes ranging from tidal variation, salinity changes (within a hyposaline range) and variable river flow. Trochamminita ’s fragmented global distribution could likely be attributed to attachment to migratory waterbirds dispersing it along major flyways such as the East Australasian Flyway where Australia acts as one of the main foraging and breeding ground for these birds. The discovery of the species in the Hay River allows some preliminary investigations of the micro-living habitat of Trochamminita and its potential means of dispersion. Molecular and more in-depth ecological studies on living T. irregularis are required to more fully understand this global and ecologically significant marsh indicator species.