A trove of New World Syscia (Formicidae, Dorylinae)

The ant genus Syscia is part of the cryptic ant fauna inhabiting leaf litter and rotten wood in the Asian and American tropics. It is a distinct clade within the Dorylinae, the subfamily from which army ants and driver ants arose. Prior to this work the genus was known from two Old World species and three New World species, each known from a single or very few collections. Extensive collecting in Middle America revealed an unforeseen diversity. Species delimitation was based on an iterative process of establishing morphospecies, obtaining DNA sequence data for each geographically separate population of each morphospecies, and revising species boundaries. Sequencing of Ultra-Conserved Element (UCE) loci was used to infer phylogenetic relationships among 130 specimens, and these results were complemented with additional mitochondrial COI (DNA barcode) data. We increased the number of known species in the New World from 3 to 57, more fully characterizing the three previously described New World species and describing 31 new species. The remaining 23 species are assigned morphospecies codes pending improved specimen coverage. Queens may occur in fully alate or brachypterous forms, and there is a wide variety of intercaste females (possibly ergatoid reproductives). All species have a similar habitus. Species identification based on morphology alone is very difficult due to continuous character variation and high similarity of phylogenetically distant species. An identification aid is provided in the form of a set of distribution maps and standard views, with species ordered by size.

Syscia蚁属隶属于栖息于亚洲和美洲热带地区叶片凋落物及朽木中的隐秘蚁类群。该属为Dorylinae亚科中一个独特的类群，而Dorylinae亚科是军蚁和工蚁的起源地。在本次研究之前，该属仅以两个旧大陆物种和三个新大陆物种为已知，每个物种均来自单一或极少数的采集样本。在中美洲的广泛采集揭示了意想不到的物种多样性。物种界定基于建立形态物种、为每个形态物种的每个地理种群获取DNA序列数据，以及修订物种边界的迭代过程。通过对超保守元件（UCE）位点的测序，推断出130个样本之间的系统发育关系，并辅以额外的线粒体COI（DNA条形码）数据。我们将新大陆已知物种的数量从3种增加到57种，更全面地描述了先前描述的三个新大陆物种，并描述了31个新物种。剩余的23个物种则被分配了形态物种代码，以备标本覆盖度提升后的进一步鉴定。蚁后可能以完全有翅或短翅的形式出现，且存在多种不同阶级的女性（可能为工蚁型的繁殖者）。所有物种都具有相似的外部形态。由于形态特征连续变异以及系统发育上距离较远的物种之间的高相似性，仅基于形态学进行物种鉴定极为困难。提供了一套分布图和标准视图作为鉴定辅助工具，物种按体型大小排序。