Monogononta is a large clade of rotifers comprised of diverse morphological forms found in a wide range of ecological habitats. Most monogonont species display cyclical parthenogenesis, where generations of asexually reproducing females are interspaced by mixis events when sexual reproduction occurs between mictic females and dwarf, haploid males. The morphology of monogonont feeding females is relatively well described, however data on male anatomy are very limited. Thus far, male musculature of only two species has been described with confocal laser scanning microscopy (CLSM) and it remains unknown how dwarfism influences the neuroanatomy of males on detailed level. Here, we provide a CLSM-based description of the nervous system of both sexes of Epiphanes senta, a freshwater monogonont rotifer. The general nervous system architecture is similar between males and females and shows a similar level of complexity. However, the nervous system in males is more compact and lacks a stomatogastric part. Comparison of the neuroanatomy between male and normal-sized feeding females provides a better understanding of the nature of male dwarfism in Monogononta. We propose that dwarfism of monogonont non-feeding males is the result of a specific case of heterochrony, called “proportional dwarfism” as they, due to their inability to feed, retain a juvenile body size, but still develop a complex neural architecture comparable to adult females. Reduction of the stomatogastric nervous system in the males correlates with the loss of the entire digestive tract and associated morphological structures.

中文翻译：

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单眼轮虫 Epiphanes senta 神经系统的形态学，重点是喂养雌性和矮雄性之间的性二态性

Monogononta 是轮虫的一个大分支，由在广泛的生态栖息地中发现的多种形态形式组成。大多数单角兽物种表现出周期性的孤雌生殖，当有性生殖发生在有性生殖的雌性和矮小的单倍体雄性之间时，几代无性繁殖的雌性被混合事件隔开。单眼喂养雌性的形态描述得比较好，但雄性解剖学的数据非常有限。到目前为止，仅用共聚焦激光扫描显微镜 (CLSM) 描述了两个物种的男性肌肉组织，并且侏儒症如何详细影响男性的神经解剖学仍然未知。在这里，我们提供了基于 CLSM 的对 Epiphanes senta（一种淡水单角轮虫）两性神经系统的描述。男性和女性的一般神经系统结构相似，并且显示出相似的复杂程度。然而，男性的神经系统更紧凑，缺乏胃胃部分。雄性和正常大小的哺乳雌性之间的神经解剖学比较有助于更好地了解 Monogononta 雄性侏儒症的性质。我们提出，单角非进食雄性的侏儒症是一种特殊的异时性病例的结果，称为“比例侏儒症”，因为它们由于无法进食而保持幼年体型，但仍发展出与成年女性。男性口胃神经系统的减少与整个消化道和相关形态结构的丧失有关。