Arcuatula tristisArcuatula tristis is a species in the genus Arcuatula, family Mytilidae, order Mytilida.Scientific classificationRankTaxonDomainEukaryotaKingdomAnimaliaPhylumMolluscaClassBivalviaOrderMytilidaFamilyMytilidaeGenusArcuatulaSpeciesArcuatula tristis