Kalmar "Haplosporidian" tana nufin wani nau'in protist na parasitic na phylum Haplosporidia. Wadannan kwayoyin halitta ana samun su a cikin mahallin ruwa kuma suna iya cutar da nau'in invertebrates na ruwa iri-iri kamar mollusks da crustaceans. Haplosporidians suna halin kasancewar kuɗaɗɗen ƙwayar cuta guda ɗaya ko ƙananan adadin spores a cikin kowane tantanin halitta. An san su da haifar da cututtuka a cikin masu masaukin su, kuma wasu nau'in haplosporidians sun kasance masu alhakin hasara mai yawa a cikin masana'antar kiwo.