Chemical cues play an important role in short-range communication of butterflies, remarkably in sexual attraction and mate choice. Differentiated scale patches on the wings of male butterflies, the androconia, are involved in the emission of pheromones. Here, we describe the androconial morphology of six sympatric species of Neotropical sulphur butterflies belonging to two genera of the Colias -clade (Pieridae) based on SEM imaging. Gas chromatography-mass spectrometry analyses were used to access the chemical compositions of androconial secretions, which were comparatively investigated to determine species-specific trends and to verify if they yield a phylogenetic signal. The androconial patches from all species are differentiated from the non-androconial male wing surface and exhibit morphological features that may act in both preventing the volatilization of secretions and facilitating the release of semiochemicals, such as high density and length of scales and large perforations in the upper lamellae. A total of 55 compounds were exclusive to the androconia, and unique chemical profiles are present in each butterfly species, verified through multivariate analysis. The majority of androconial compounds were autapomorphic for each species and only four were dominant in more than one species. Cluster analyses placed the two species of Anteos in a single clade, but otherwise evidenced low similarities in the androconial secretion compositions among species, and a moderate correlation between genetic distances and chemical dissimilarities was obtained. Our findings suggest that androconial substances are involved in mating-oriented strategies and might be associated with the evolutionary history of the reproductive isolation of sulphurs.

中文翻译：

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特殊的雄性鳞片隐藏了同域硫蝴蝶（鳞翅目：蝶科：科利亚丁亚科）的物种特异性信息素化学物质

化学线索在蝴蝶的短距离交流中起着重要作用，在性吸引和配偶选择方面尤为突出。雄性蝴蝶雄性蝴蝶翅膀上的分化鳞片与信息素的释放有关。在这里，我们基于 SEM 成像描述了属于 Colias 进化枝（Pieridae）两个属的 6 种新热带硫蝴蝶的同域物种的雄体形态。气相色谱-质谱分析用于获取雄性分泌物的化学成分，对其进行比较研究以确定物种特异性趋势并验证它们是否产生系统发育信号。所有物种的雄性斑块都与非雄性雄性翅膀表面不同，表现出的形态特征可能在防止分泌物挥发和促进化学信息素释放方面起作用，例如高密度和长度的鳞片和大穿孔上层。共有 55 种化合物是雄蕊属独有的，每个蝴蝶物种中都存在独特的化学特征，通过多变量分析进行验证。大多数雄性化合物对每个物种都是自体变形的，只有四种在一个以上的物种中占优势。聚类分析将两个 Anteos 物种置于一个进化枝中，但在其他方面表明物种间雄性分泌成分的相似性较低，并且获得了遗传距离和化学差异之间的中等相关性。我们的研究结果表明，雄性物质涉及以交配为导向的策略，并且可能与硫的生殖隔离的进化历史有关。