Despite their large size and striking markings, the identification of bumble bees (Bombus spp.) is surprisingly difficult. This is particularly true for three North American sympatric species in the subgenus Pyrobombus that are often misidentified: B. sandersoni Franklin, B. vagans Smith B. perplexus Cresson. Traditionally, the identification of these cryptic species was based on observations of differences in hair coloration and pattern and qualitative comparisons of morphological characters including malar length. Unfortunately, these characteristics do not reliably separate these species. We present quantitative morphometric methods to separate these species based on the malar length to width ratio (MRL) and the ratios of the malar length to flagellar segments 1 (MR1) and 3 (MR3) for queens and workers, and validated our determinations based on DNA barcoding. All three measurements discriminated queens of B. sandersoni and B. vagans with 100% accuracy. For workers, we achieved 99% accuracy by combining both MR1 and MR3 measurements, and 100% accuracy differentiating workers using MRL. Moreover, measurements were highly repeatable within and among both experienced and inexperienced observers. Our results, validated by genetic evidence, demonstrate that malar measurements provide accurate identifications of B. vagans and B. sandersoni. There was considerable overlap in the measurements between B. perplexus and B. sandersoni. However, these species can usually be reliably separated by combining malar ratio measurements with other morphological features like hair color. The ability to identify bumble bees is key to monitoring the status and trends of their populations, and the methods we present here advance these efforts.

中文翻译：

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使用DNA条形码验证形态计量学，以可靠地分离出Bombus Cresson（膜翅目：Apidae）的三个隐性物种

尽管它们很大且有明显的标记，但是鉴定大黄蜂（Bombus spp。）却非常困难。这对于经常被误认的北美洲火棘属中的三种北美同胞物种尤其如此：B. sandersoni Franklin，B. vagans Smith B. perplexusCresson。传统上，对这些隐性物种的鉴定是基于对毛发颜色和图案差异的观察以及对包括苹果酸长度的形态特征的定性比较。不幸的是，这些特征不能可靠地分离这些物种。我们提供了定量形态计量学方法，根据皇后和工人的黄斑长宽比（MRL）和鞭毛段与鞭毛段1（MR1）和3的鞭毛段之比来分离这些物种，并基于DNA条形码。所有这三个测量值都区分了B. sandersoni和B. vagans的女王准确度达100％。对于工人，我们通过结合MR1和MR3测量获得了99％的精度，并使用MRL区分了100％的工人精度。而且，在经验丰富和经验不足的观察者内部和之中，测量都是高度可重复的。我们的结果（已通过遗传证据验证）表明，苹果黑斑病的测量可以准确识别B. vagans和B. sandersoni。丛生芽孢杆菌和桑德森芽孢杆菌之间的测量存在很大的重叠。但是，通常可以通过将苹果酸比率测量值与其他形态特征（如头发颜色）结合起来，可靠地分离这些物种。识别大黄蜂的能力是监测其种群状况和趋势的关键，我们在此介绍的方法将推动这些努力。