Data from: Molecular phylogenetics unveils the ancient evolutionary origins of the enigmatic fairy armadillos

Fairy armadillos or pichiciegos (Xenarthra, Dasypodidae) are among the most elusive mammals. Due to their subterranean and nocturnal lifestyle, their basic biology and evolutionary history remain virtually unknown. Two distinct species with allopatric distributions are recognized: Chlamyphorus truncatus is restricted to central Argentina, while Calyptophractus retusus occurs in the Gran Chaco of Argentina, Paraguay, and Bolivia. To test their monophyly and resolve their phylogenetic affinities within armadillos, we obtained sequence data from modern and museum specimens for two mitochondrial genes (12S RNA [MT-RNR1] and NADH dehydrogenase 1 [MT-ND1]) and two nuclear exons (breast cancer 1 early onset exon 11 [BRCA1] and von Willebrand factor exon 28 [VWF]). Phylogenetic analyses provided a reference phylogeny and timescale for living xenarthran genera. Our results reveal monophyletic pichiciegos as members of a major armadillo subfamily (Chlamyphorinae). Their strictly fossorial lifestyle probably evolved as a response to the Oligocene aridification that occurred in South America after their divergence from Tolypeutinae around 32 million years ago (Mya). The ancient divergence date (∼17 Mya) for separation between the two species supports their taxonomic classification into distinct genera. The synchronicity with Middle Miocene marine incursions along the Paraná river basin suggests a vicariant origin for pichiciegos by the disruption of their ancestral range. Their phylogenetic distinctiveness and rarity in the wild argue in favor of high conservation priority.

倭犰狳（Fairy armadillos，亦称pichiciegos）隶属于异关节总目（Xenarthra）犰狳科（Dasypodidae），是最为隐秘的哺乳动物类群之一。由于其营地下穴居与夜行性生活，学界对其基础生物学特征与演化历程几乎一无所知。目前已确认两个具有异域分布的独立物种：倭犰狳（Chlamyphorus truncatus）仅分布于阿根廷中部，而大倭犰狳（Calyptophractus retusus）则见于阿根廷、巴拉圭与玻利维亚的大查科（Gran Chaco）地区。为验证倭犰狳的单系群属性，并明确其在犰狳科内的系统发育亲缘关系，我们从现代标本与馆藏标本中获取了两类分子标记的序列数据：2个线粒体基因（12S核糖体RNA [12S RNA, MT-RNR1] 与烟酰胺腺嘌呤二核苷酸脱氢酶亚基1 [NADH dehydrogenase 1, MT-ND1]），以及2个核外显子（乳腺癌1型早期发病基因11号外显子 [BRCA1] 与血管性血友病因子28号外显子 [VWF]）。系统发育分析为现生异关节类属级类群构建了参考系统发育树与分化时间标尺。本研究结果证实，倭犰狳为单系群，隶属于犰狳科的一个主要亚科——倭犰狳亚科（Chlamyphorinae）。倭犰狳专性穴居的生活方式，可能是在其与三带犰狳亚科（Tolypeutinae）约3200万年前分化后，为适应南美渐新世时期的干旱化事件而演化形成。两个物种间约1700万年前的古老分化时间，佐证了将它们划分为不同属的分类学处理。该分化时间与巴拉那河流域中中新世时期的海侵事件同步，提示倭犰狳类群的起源为祖先分布区被破坏所导致的异域分化。倭犰狳独特的系统发育地位，加之野外种群极为稀有，均表明其应被赋予极高的保护优先级。