The freshwater rotifer Kellicottia bostoniensis (Rousselet, 1908), native from North America, has been considered invasive in European, Russian and South American waterbodies. More than reporting its presence, for the first time, in Araguaia River, which plays critical role in a set of floodplain systems in the Brazilian savanna, we aim to understand how this invader react to new physical, chemical and hydrodynamics conditions, which can be helpful for predicting its invasiveness and colonization success in other similar non-native ranges. We use population data of K. bostoniensis and environmental variables surveyed across the meandering middle-stretch of the Araguaia River. The highest frequencies of K. bostoniensis were registered in sites of lower mean temperatures, higher pH and dissolved oxygen at sites with higher hydrodynamics. However, the highest abundance was found in a backwater site, a more lentic habitat in which total body size was slightly higher than those with lotic conditions. Both the abundance values and body length were the lowest registered in non-native areas, suggesting the initial phase of the invasion process. Also, the trade-off between abundance and body size may allow population to persist in flowing water conditions, thus playing fundamental role in population recruitment and dispersal, favoring the propagation of this organism in the river curse and adjacent environments. Specifically, stepping stones created by the river meanders would increase population growth and the rapid spread of K. bostoniensis through Araguaia River. Due to its wide environmental tolerance, morphological plasticity and high dispersal ability, we further anticipate continued dispersion of K. bostoniensis to other Brazilian basins highlighting the need for persistent monitoring upstream and downstream of this freshwater ecotone.

淡水轮虫Kellicottia bostoniensis (Rousselet, 1908) 原产于北美，被认为是欧洲、俄罗斯和南美水体的入侵物种。除了首次报告它在巴西稀树草原的一系列洪泛区系统中发挥关键作用的阿拉瓜亚河（Araguaia River）的存在之外，我们还旨在了解这种入侵者如何对新的物理、化学和流体动力学条件做出反应，这些条件可以是有助于预测其在其他类似的非本地范围内的侵袭性和定植成功率。我们使用K. bostoniensis的种群数据和在 Araguaia 河蜿蜒的中段调查的环境变量。K. bostoniensis的最高频率在流体动力学较高的地点，平均温度较低、pH 值较高和溶解氧较高的地点登记。然而，在死水地区发现了最高的丰度，这是一个更安静的栖息地，其总体尺寸略高于具有流动条件的栖息地。丰度值和体长在非本土地区登记的最低，表明入侵过程的初始阶段。此外，丰度和体型之间的权衡可能允许种群在流动的水条件下持续存在，从而在种群招募和分散中发挥重要作用，有利于这种生物在河流诅咒和邻近环境中的繁殖。具体来说，河流蜿蜒形成的垫脚石会增加人口增长和波士顿克氏杆菌的快速传播穿过阿拉瓜亚河。由于其广泛的环境耐受性、形态可塑性和高分散能力，我们进一步预计K. bostoniensis将继续分散到巴西其他盆地，突出了持续监测该淡水交错带上游和下游的必要性。