Many taxonomic groups successfully exploit groundwater environments and have adapted to a subterranean (stygobiotic) existence. Among these groups are freshwater gastropods (stygosnails), which represent a widespread and taxonomically diverse component of groundwater ecosystems in North America. However, owing to sampling difficulty and lack of targeted study, stygosnails remain among the most understudied of all subterranean groups. We conducted a literature review to assess the biodiversity and geographic associations of stygosnails, along with the threats, management activities, and policy considerations related to the groundwater systems they inhabit. We identified 39 stygosnail species known to occur in a range of groundwater habitats from karst regions in the United States and Mexico. Most stygosnails exhibit extreme narrow-range endemism, resulting in a high risk of extinction from a single catastrophic event. We found that anthropogenically driven changes to surface environments have led to changes in local hydrology and degradation of groundwater systems inhabited by stygosnails such as increased sedimentation, introduction of invasive species, groundwater extraction, or physical collapse of water-bearing passages. Consequently, 32 of the 39 described stygosnail species in the United States and Mexico have been assessed as imperiled under NatureServe criteria, and 10 species have been assessed as threatened under International Union for Conservation of Nature criteria. Compared with surface species of freshwater snails, stygosnail conservation is uniquely hindered by difficulties associated with accessing subterranean habitats for monitoring and management. Furthermore, only three species were found to have federal protection in either the United States or Mexico, and current laws regulating wildlife and water pollution at the state and federal level may be inadequate for protecting stygosnail habitats. As groundwater systems continue to be manipulated and relied on by humans, groundwater-restricted fauna such as stygosnails should be studied so unique biodiversity can be protected.

中文翻译：

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美国和墨西哥的地下淡水腹足动物生物多样性和保护

许多分类群成功地开发了地下水环境并适应了地下（stygobiotic）的存在。其中包括淡水腹足动物（stygosnails），它们代表了北美地下水生态系统中广泛且分类多样的组成部分。然而，由于采样困难和缺乏针对性的研究，stygosnails 仍然是所有地下群体中研究最少的。我们进行了文献综述，以评估 stygosnails 的生物多样性和地理关联，以及与它们栖息的地下水系统相关的威胁、管理活动和政策考虑。我们确定了 39 种已知存在于美国和墨西哥喀斯特地区地下水栖息地的 stygosnail 物种。大多数stygosnails表现出极端狭窄的地方性，导致因单一灾难性事件而灭绝的高风险。我们发现，人为驱动的地表环境变化导致了当地水文的变化和 stygosnails 居住的地下水系统的退化，例如沉积增加、入侵物种的引入、地下水提取或含水通道的物理坍塌。因此，美国和墨西哥描述的 39 种 stygosnail 物种中有 32 种已根据 NatureServe 标准被评估为濒危物种，10 种根据国际自然保护联盟标准被评估为受威胁物种。与淡水蜗牛的地表物种相比，stygosnail 的保护受到了与进入地下栖息地进行监测和管理相关的困难的独特阻碍。此外，在美国或墨西哥，仅发现三个物种受到联邦保护，而目前在州和联邦层面监管野生动物和水污染的法律可能不足以保护 stygosnail 栖息地。随着地下水系统继续被人类操纵和依赖，应研究受地下水限制的动物群，如 stygosnails，以便保护独特的生物多样性。