Fundación Miguel Lillo - Unidad Ejecutora Lillo (CONICET), San Miguel de Tucumán, Tucumán, Argentina.
Instituto de Bio y Geociencias del NOA (IBIGEO-CONICET), Rosario de Lerma, Salta, Argentina.
PLoS One. 2019 Jul 10;14(7):e0218810. doi: 10.1371/journal.pone.0218810. eCollection 2019.
Freshwater sulfide springs have extreme environmental conditions that only few vertebrate species can tolerate. These species often develop a series of morphological and molecular adaptations to cope with the challenges of life under the toxic and hypoxic conditions of sulfide springs. In this paper, we described a new fish species of the genus Jenynsia, Anablepidae, from a sulfide spring in Northwestern Argentina, the first in the family known from such extreme environment. Jenynsia sulfurica n. sp. is diagnosable by the lack of scales on the pre-pelvic area or the presence of a single row of scales, continuous or not, from the isthmus to the bases of the pelvic fins. Additionally, it presents a series of morphological and molecular characteristics that appear convergent with those seen in other fish species (e.g., Poeciliids) inhabiting sulfide springs. Most notably, J. sulfurica has an enlarged head and postorbital area compared to other fish of the genus and a prognathous lower jaw with a hypertrophied lip, thought to facilitate respiration at the air-water interface. Analyses of cox1 sequence showed that J. sulfurica has two unique mutations resulting in amino acid substitutions convergent to those seen in Poeciliids from sulfide springs and known to provide a physiological mechanism related to living in sulfide environments. A phylogenetic analysis, including molecular and morphological characters, placed J. sulfurica as sister taxa to J. alternimaculata, a species found in nearby, non-sulfide habitats directly connected to the sulfide springs. Thus, it can be inferred that the selection imposed by the presence of H2S has resulted in the divergence between these two species and has potentially served as a barrier to gene flow.
淡水硫化物泉具有极端的环境条件，只有少数脊椎动物物种能够耐受。这些物种通常会发展出一系列形态和分子适应机制，以应对硫化物泉有毒和缺氧环境下的生存挑战。在本文中，我们描述了一种来自阿根廷西北部硫化物泉的新的詹尼西亚鱼属鱼类，这是该科中第一种已知生活在这种极端环境中的鱼类。詹尼西亚硫鱼（Jenynsia sulfurica n. sp.）可通过缺乏前骨盆区域的鳞片或存在从峡部到臀鳍基部连续或不连续的单列鳞片来鉴别。此外，它还具有一系列形态和分子特征，这些特征与栖息在硫化物泉中的其他鱼类（例如，胎生鳉科鱼类）的特征相似。值得注意的是，与该属的其他鱼类相比，J. sulfurica 的头部和眶后区域较大，下颌前突，唇部肥大，这被认为有助于在气-水界面呼吸。cox1 序列分析表明，J. sulfurica 有两个独特的突变，导致氨基酸取代，与来自硫化物泉的胎生鳉科鱼类的突变相似，这些突变被认为与生活在硫化物环境中有关。包括分子和形态特征在内的系统发育分析将 J. sulfurica 置于与 J. alternimaculata 密切相关的姊妹群地位，后者存在于附近直接与硫化物泉相连的非硫化物生境中。因此，可以推断出 H2S 的存在所施加的选择导致了这两个物种的分化，并可能成为基因流动的障碍。
