We reinvestigated Pycnothrix monocystoides Schubotz, 1908 from the intestine of the African Rock Hyrax (Procavia capensis) collected from Saudi Arabia, using protargol impregnation and electron microscopy. Pycnothrix is a unique, up to 5mm long intestinal ciliate with about two million cilia and many cytostomes (i.e. actual cytostome plus cytopharynx; polycytopharyngy) in the oral furrow (∼vestibulum) that extends on both sides of the cell. Both walls of the furrow are covered by adoral membranelle-like ciliary polymerizations. To the right of the furrow and the cytostomes there are small ciliary fields, very likely homologous to the “dorsal brush” found in free-living litostomateans. The molecular investigations show Pycnothrix as sister to Balantidium and endemic Australian intestinal ciliates, e.g. the genus Bandia. We propose that the common ancestor had both an oral furrow and a special ciliary field both similar to that found in Balantidium. The unique morphology (polycytopharyngy) and the rather distinct molecular separation suggest maintenance of the family status given by Poche (1913).

中文翻译：

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多核纤毛虫 Pycnothrix monocystoides Schubotz 的形态学和分子系统发育，1908 年

我们使用 protargol 浸渍和电子显微镜重新研究了 1908 年从沙特阿拉伯收集的非洲岩蹄兔 (Procavia capensis) 肠道中的 Pycnothrix monocystoides Schbotz。Pycnothrix 是一种独特的、长达 5 毫米的肠道纤毛虫，在细胞两侧延伸的口腔沟（～前庭）中具有约 200 万根纤毛和许多细胞口（即实际的细胞口加细胞咽；多细胞咽）。犁沟的两壁都被膜状纤毛聚合体覆盖。在犁沟和细胞造口的右侧有小的睫状区域，很可能与自由生活的石口动物中发现的“背刷”同源。分子研究表明，Pycnothrix 是 Balantidium 和澳大利亚地方性肠道纤毛虫（例如 Bandia 属）的姐妹。我们提出共同祖先既有口腔沟又有特殊的睫状区，这两者都与在 Balantidium 中发现的相似。独特的形态（多细胞咽）和相当明显的分子分离表明维持了 Poche (1913) 给出的家族地位。