Oxyuricassis ekstromi n. sp. is the third species of the genus described from the intestine of Lasiancistrus saetiger Armbruster in Brazil. This species can be easily differentiated from its congeners by the presence of a tooth-like sclerotized piece that occupies half of the stoma and absence of spine projections on the tail of both males and females. Also, males of the new species lack caudal alae present in Oxyuricassis coronatus and Oxyuricassis hexaspinatus. Additionally, we observed a different number and pattern of the distribution of cloacal papilla; males of O. coronatus and O. hexaspinatus have 1 pair of pre-cloacal and 2 pairs of post-cloacal papillae; while the new species has 1 pre-cloacal and 3 post-cloacal pairs of papillae.

Oxyuricassis ekstromi ñ。sp。是巴西Lasiancistrus saetiger Armbruster肠道中描述的第三大类。该物种可以很容易地与同类动物区分开来，因为它们存在着一个占齿气孔一半的齿状硬化块，并且在雄性和雌性的尾巴上都没有脊柱突起。而且，新物种的雄性缺乏在冠状牛Ox和六角牛Ox中存在的尾。此外，我们观察到了泄殖腔乳头分布的数量和模式有所不同。雄性O.冠斑和O. hexaspinatus有1对泄殖腔前乳腺和2对泄殖腔后乳头; 新物种有1对泄殖腔前和3对泄殖腔后的乳头。