We discovered a dense population of tubificine worms attributed to the genus Limnodrilus (Clitellata: Naididae; Tubificinae) in the sulfidic springs of the former Blount Springs resort in northern Alabama. To determine the phylogenetic placement of this population, we compared our samples’ morphological characters and commonly used molecular sequences to those of other Limnodrilus species. Using mitochondrial and nuclear DNA sequence analysis of four loci, we confidently identify the worm as belonging in the Limnodrilus hoffmeisteri species complex, to the exclusion of L. sulphurensis that thrives in a high sulfide Colorado cave. This adaptation, therefore, represents a habitat extension within the normally freshwater L. hoffmeisteri complex and as such may represent an independent acquisition of sulfide tolerance. Both maximum likelihood tree methods and the more conservative tree-independent splits analysis of molecular data place the Blount Springs population within clade III, one of ten L. hoffmeisteri clades proposed in previous work. In contrast, the Blount Springs tubificine morphologically more closely resembles worms in clade I. Additional phylogenetic data may be necessary to pinpoint its placement within L. hoffmeisteri.

我们在阿拉巴马州北部前布朗特温泉度假村的硫化泉水中发现了密集的水管蠕虫种群，属于Limnodrilus属（Clitellata：Naididae；Tubificinae）。为了确定该种群的系统发育位置，我们将样本的形态特征和常用分子序列与其他湖水丝虫物种进行了比较。通过对四个位点的线粒体和核 DNA 序列分析，我们确信该蠕虫属于Limnodrilus hoffmeisteri物种复合体，排除了在高硫化物科罗拉多洞穴中繁衍生息的L. sulfurensis 。因此，这种适应代表了正常淡水L. hoffmeisteri复合体内的栖息地扩展，因此可能代表了硫化物耐受性的独立获得。最大似然树方法和更保守的与树无关的分子数据分裂分析都将布朗特斯普林斯群体置于进化枝 III 中，这是先前工作中提出的十个L. hoffmeisteri进化枝之一。相比之下，Blount Springs tubeificine 在形态上更类似于进化枝 I 中的蠕虫。可能需要额外的系统发育数据来确定其在L. hoffmeisteri 中的位置。