Geographical range is one of the critical features for species conservation assessment. Nevertheless, species distribution is frequently unknown, undervalued or overlooked. During a broad taxonomic and floristic study of the southern South American prickly pear species (Opuntia spp.), new records of a species previously considered endemic to Argentina have been found in Uruguay and Brazil. Molecular phylogenetic inference was carried out to further evaluate the identity of the new records, and ecological niche models were implemented to test how the new records would fit in the previous known distribution of the species. Through molecular and morphological evidence, we confirmed the new records of Opuntia bonaerensis for Brazilian and Uruguayan floras and discussed its phylogenetic relationship and morphological similarities with closely related species. Our new records uncovered a distribution pattern congruent with the Neotropical Peripampasic Orogenic Arc, which must be further explored to better determine the biogeographic history of the species. Ecological niche models (ENM) revealed that O. bonaerensis likely had a putative ancient distribution across the grasslands and shrublands in the Pampean region largely congruent with the populations found in Brazil and Uruguay, suggesting relictual Pleistocene populations of the species and the role of glacial/interglacial cycles on the distribution of the species. In a prospective climate change scenario, ENM suggests that the species would in general be more restricted to the southernmost limits of the Pampa region and previous outlying records from Mendoza (Argentina) are a putative future refuge for O. bonaerensis. The importance of these new records for biodiversity and conservation assessment efforts that are ongoing at different scales in Brazil and neighboring areas is highlighted.

地理范围是物种保护评估的关键特征之一。然而，物种分布常常是未知的，被低估或被忽视的。在对南美南美花梨品种（仙人掌属）进行广泛的分类学和植物学研究期间，在乌拉圭和巴西发现了以前被认为是阿根廷特有种的新记录。进行了分子系统发育推断，以进一步评估新记录的身份，并实施了生态位模型以测试新记录如何适合该物种的先前已知分布。通过分子和形态学证据，我们确认了仙人掌的新记录。以及巴西和乌拉圭的植物区系，并讨论了其与密切相关物种的系统发生关系和形态相似性。我们的新记录揭示了与新热带近缘造山弧一致的分布模式，必须进一步探索以更好地确定该物种的生物地理历史。生态位模型（ENM）揭示了博纳尔山羊草可能在Pampean地区的草地和灌木丛中有一个古老的推测分布，与巴西和乌拉圭的种群基本一致，这表明该物种属于遗存更新世种群，以及冰川/冰川间的循环对物种分布的作用。在潜在的气候变化情景中，ENM认为该物种通常将更局限在潘帕地区的最南端，而门多萨（阿根廷）的先前偏远记录是假定的O. bonaerensis避难所。强调了这些新记录对于在巴西及周边地区以不同规模进行的生物多样性和保护评估工作的重要性。