Sixteen species of Costus s.s. are cited to Brazil, all of which can be found in the Brazilian Amazon, while only three also grow in the Atlantic Forest: C. arabicus, C. scaber, and C. spiralis. Studies of the genus from the Brazilian Atlantic Forest evidenced a distinctive fourth taxon, similar overall to C. spiralis, which is an ornithophilous species, however the flower morphology of this new taxon indicates it to be melittophilous. Hybridization and polyploidy (allopolyploidy or autopolyploidy) may play a role as an important source for evolutionary events, especially in recent speciose lineages such as Neotropical Costus. Here we investigated the evolutionary origin of this interesting Costus species using an integrative approach. This approach comprised a morphological analysis, cytogenetic analyses (chromosome counts, CMA/DAPI staining, and fluorescent in situ hybridization), genome size estimations, and a molecular phylogenetic reconstruction (using the plastid regions rps16 and trnL-F, and the nuclear ITS and ETS), aiming to answer the following questions: is it a hybrid?; is it an autopolyploid of C. spiralis?; or, if it is a different species, is it even phylogenetically related to C. spiralis or C. arabicus? The studies performed did not indicate any evidence of polyploidy, however, a chromosomal polymorphism was observed between the populations of the taxon studied. The phylogenetic position of this peculiar taxon with C. erythrophyllus, C. spiralis, and C. varzearum also excludes the putative partial heritage of C. arabicus which had been previously hypothesized. Our results confirm that it is a new, undescribed species, which is confirmed by our morphological observations of floral features. A complete taxonomic treatment of the new species is provided, including a key for the species of the genus in the Atlantic Forest.

中文翻译：

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自然杂交、同源多倍体还是新物种？一个来自巴西大西洋森林的独特的 Costus 物种（Costaceae）的综合案例研究

巴西引用了 16 种 Costus ss，所有这些都可以在巴西亚马逊地区找到，而大西洋森林中也只有三种：C. arabicus、C. scaber 和 C. spinis。对来自巴西大西洋森林的该属的研究证明了一个独特的第四个分类群，总体上类似于 C. spinis，后者是一种嗜鸟物种，但是这个新分类群的花形态表明它是嗜蜂的。杂交和多倍体（异源多倍体或同源多倍体）可能是进化事件的重要来源，尤其是在新热带科斯图斯等最近的物种谱系中。在这里，我们使用综合方法研究了这个有趣的 Costus 物种的进化起源。这种方法包括形态学分析、细胞遗传学分析（染色体计数、CMA/DAPI 染色、和荧光原位杂交）、基因组大小估计和分子系统发育重建（使用质体区域 rps16 和 trnL-F，以及核 ITS 和 ETS），旨在回答以下问题：它是杂种吗？它是 C. spinis 的同源多倍体吗？或者，如果它是一个不同的物种，它甚至在系统发育上与 C. spinis 或 C. arabicus 相关吗？进行的研究没有表明任何多倍体的证据，但是，在所研究的分类群的种群之间观察到了染色体多态性。这种特殊分类群与 C. erythrophyllus、C. spinis 和 C. varzearum 的系统发育位置也排除了先前假设的 C. arabicus 的假定部分遗传。我们的结果证实它是一个新的，未描述的物种，我们对花卉特征的形态观察证实了这一点。提供了新物种的完整分类处理，包括大西洋森林中该属物种的关键。