Adacna fragilis

Wesselingh, Frank, Poorten, Jan Johan ter, Kijashko, Pavel, Albrecht, Christian, Anistratenko, Olga Yu, Frolov, Pavel, Gándara, Alberto Martinez, Gittenberger, Arjan, Gogaladze, Aleksandre, Mikhail Karpinsky, Popa, Luis, Sands, Arthur F, Vandendorpe, Justine & Wilke, Thomas, 2019, Mollusc species from the Pontocaspian region - an expert opinion list, ZooKeys 827, pp. 31-124 : 35-36

Adacna fragilis Milaschewitsch, 1908

*1908 Adacna fragilis Milaschewitch: 992-993.

1973 Hypanis laeviuscula fragilis Milaschevitsch, 1916. - Grossu: 145.

?2006b Hypanis (Adacna) laeviuscula fragilis (Milachevitch, 1908). - Munasypova-Motyash: 522.

2009 Adacna (Adacna) fragilis Milaschevich, 1908. - Popa et al.: 13, fig. 5.

2016 Adacna (Adacna) fragilis Milaschewitsch, 1908. - Vinarski and Kantor: 64.

Status. Pontocaspian species, Black Sea Basin, status uncertain.

Type locality. Odessa region, Dniester liman and Katlabhuk Lake (Ukraine: Vinarski and Kantor 2016).

Distribution. Danube Delta region and NW Black Sea Basin coastal areas of Ukraine.

Taxonomic notes. We are uncertain about the status of Adacna fragilis Milaschewitch, 1908. The Black Sea Basin material has a wide variety of shapes and often is thinner and sometimes more elliptical than the Caspian A. laeviuscula . Both forms were synonymised by Graf and Cummings (2018) and indicated as a possible synonym in MolluscaBase (2018b). However, the Black Sea Basin occurrences are recorded from (coastal) lakes and small rivers suggesting little or only partial overlap in the ecological (and especially salinity) preferences of A. laeviuscula (e.g., Munasypova-Motyash 2006a, b, Popa et al. 2009). We are uncertain if A. fragilis might constitute a geographical subspecies (a status advocated by Grossu 1973), and further molecular analyses are needed to clarify the status of the Black Sea taxon.

Remarks. The species has been reported alive by Popa et al. (2009) from the Razim Lake complex on the Romanian Black Sea coast.

Conservation status. Not assessed.