四极虫属(学名:Chloromyxum)是刺胞动物门、粘体动物亚门、粘孢子虫纲、双壳目、四极虫科的一属,属于寄生性原生动物。该属物种广泛分布于北美和澳大利亚,寄生于草鱼、鲢、青鱼、赤眼鳟、鳊、鳙、胡子鲶、鳢、鲶、麦穗鱼等淡水鱼类的胆囊中。孢子有4个极囊,常见的有椭圆形四极虫(C. ellipticum Lee & Nie)、鲢四极虫等20多种。
形态特征
四极虫属的孢子有4个极囊,紧位于前端。壳表面常有四条纹或嵴。

生活习性
腔寄生或组织寄生。
下属物种
本属包括以下物种:
Chloromyxum argusi Chandran, Zacharia & Sanil, 2018Chloromyxum atlantoraji Cantatore, Irigoitia, Holzer & BartošováChloromyxum caudatum Thélohan, 1895Chloromyxum dogieli Kovaljova, 1988Chloromyxum esocinum Dog'el & Bychowsky, 1934湖北四极虫 Chloromyxum hupehensis Li et Nie, 1973Chloromyxum fluviatile Thélohan, 1892Chloromyxum koi Fujita, 1913Chloromyxum kotorensis Lubat, Radujkovic, Marques & Bouix, 1989Chloromyxum levigatum Jameson, 1931Chloromyxum leydigi Mingazzini, 1890Chloromyxum magnum Awerinzew, 1913Chloromyxum menticirrhi Casal, Garcia, Matos, Monteiro, Matos & Azevedo, 2009Chloromyxum mrigalae Tripathi, 1953Chloromyxum noblei Moser, Kent & Dennis, 1989Chloromyxum osmanovi Karataev, 1983Chloromyxum ovatum Jameson, 1929Chloromyxum partistriatus Kovaleva, Donec & Kolesnikova, 1989Chloromyxum proterorhini Molnár, 1992Chloromyxum psetti Kovaleva, Donec & Kolesnikova, 1989Chloromyxum salamandrae Upton, McAllister & Trauth, 1995Chloromyxum schulmani Kovaljova, 1988Chloromyxum striatellus Kovaljova, 1988Chloromyxum trachuri Iskov & Karataev, 1984Chloromyxum trilineatum Sekiya, Rosyadi, Zhang & Sato, 2019Chloromyxum truttae Léger, 1906Chloromyxum zearaji Cantatore, Irigoitia, Holzer & Bartošová