This species was previously included in the circum-Mediterranean Potomida littoralis. However, recent phylogenetic studies (Froufe et al. 2016) recognised the distinction of three species within the genus Potomida, namely P. littoralis in north-western African and south-western European countries (Algeria, Tunisia, Morocco, Spain, Portugal and France), P. acarnanica in Greece, and P. semirugata in Türkiye and the Middle East.

Potomida acarnanica is a European endemic species, where it occurs in the lower Acheloos River basin (a single section in the lower part of the drainage) in western Greece and in the Pamisos River in the southwestern part of the Peloponnese peninsula, also in Greece. It is assessed as Endangered (EN B1ab(i,ii,iii)+2ab(i,ii,iii)) based on the estimates of the extent of occurrence (EOO) of 2,001 km² and an area of occupancy (AOO) of 96 km². There is also an estimated continuing decline in AOO, EOO, and habitat quality. No study on the population trends exists for this species, but it has been declining at one of the two locations. The population is considered to be highly fragmented, occurring in only two locations, the Pamisos and Acheloos river basins in western Greece. There are currently no conservation measures in place for this species.

The species is endemic to Greece, where it occurs in the lower Acheloos River basin (a single section in the lower part of the drainage) in western Greece and in the Pamisos River in the southwestern part of the Peloponnese peninsula (Froufe et al. 2016). The type locality for this species is recorded as Lake Trichonis, but surveys within the lake in 2013 found no trace of the species; lakes are not the optimal habitat for Potomida species, except for lotic sections or subterranean inflow areas (M. Lima pers. comm. 2023).

There are no studies on population trends for this species, although the Pamisos River population has lost more than 80% of its original habitat due to urbanisation and pollution from the city of Kalamata (M. Lopes-Lima pers. obs. 2022). The subpopulation of the Acheloos River basin is also thought to be declining due to the instability of hydrological regimes caused by dams.

The species occurs in lotic sections of the Pamisos, Acheloos and Dimikos rivers, and has also been recorded from Lake Lysimachia (a very old shell record, its current presence is not confirmed) (Froufe et al. 2016).

Although there are no studies on its ecology and biology, the species is thought to have the typical unique reproductive features of Unionidae species, including larval parental care (i.e. brooding) and larval parasitism on freshwater fish (and occasionally other vertebrates) (Lopes-Lima et al. 2017, Modesto et al. 2018). The host fish species are unknown.

In the River Pamisos subpopulation, the species is threatened by urbanisation and urban pollution (e.g. treated and untreated sewage). Agro-industrial pollution (e.g. olive mill effluent), direct agricultural pollution, over-abstraction of water for irrigation and sediment dredging (to increase water flows) are also common threats. Predictions of global warming for the region should also be considered as a strong plausible threat to the species, especially in the Pamisos River.

The main threats in the Acheloos river basin are pollution (nutrient loads and agricultural effluents), river fragmentation, changes in the hydrological regime and habitat degradation due to dams.

No use or trade is known for this species.

There are no known conservation actions in place for Potomida acarnanica, although they are urgently needed to reverse the rate of decline of this species. An action plan should be developed and implemented to guide the implementation of conservation actions. The sections of the lower Acheloos River are included in the Achelou Valley And Swamp Mountains Natura 2000 site.

The maintenance of ecological flows and river rehabilitation measures that increase the persistence of water in watercourses, such as the replanting of riparian buffers, the restoration of original meandering channels and the restriction of water and sediment extraction activities, are urgently needed to improve the status of river basins for P. acarnanica, especially in the Pamisos River. The Pamisos River subpopulation should also urgently be selected for protection to avoid extirpation. Further to this, it is recommended that the implementation of existing legislation to protect the species and its habitats and to mitigate the effects of global warming, be strengthened throughout the region by establishing and enforcing minimum ecological flows for the species. Outreach activities to all relevant public and private stakeholders and the general public would also be beneficial to raise awareness of the rarity, threatened conservation status and ecological importance of this species.

Future surveys are needed to improve knowledge of the species distribution, population structure and abundance, and long-term monitoring programmes should also be implemented to assess population trends. Increased knowledge of the life history, ecology and habitat requirements of the species is essential to support conservation efforts.