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Billions of specimens can be found in natural history museum collections around the world, holding potential molecular secrets to be unveiled. Among them are intriguing specimens of rare families of moths that, while represented in morphology-based works, are only beginning to be included in genomic studies: Pseudobistonidae, Sematuridae, and Epicopeiidae. These three families are part of the superfamily Geometroidea, which has recently been defined based on molecular data. Here we chose to focus on these three moth families to explore the suitability of a genome reduction method, target enrichment (TE), on museum specimens. Through this method, we investigated the phylogenetic relationships of these families of Lepidoptera, in particular the family Epicopeiidae. We successfully sequenced 25 samples, collected between 1892 and 2001. We use 378 nuclear genes to reconstruct a phylogenetic hypothesis from the maximum likelihood analysis of a total of 36 different species, including 19 available transcriptomes. The hypothesis that Sematuridae is the sister group of Epicopeiidae + Pseudobistonidae had strong support. This study thus adds to the growing body of work, demonstrating that museum specimens can successfully contribute to molecular phylogenetic studies.
The ant genus SysciaRoger, 1861 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 arose. Prior to this work, the genus comprised seven species, each known from a single or very few collections. Extensive collecting in Middle America revealed an unexpected and challenging diversity of morphological forms. Locally distinct forms could be identified at many sites, but assignment of specimens to species spanning multiple sites was problematic. To improve species delimitation, Ultra-Conserved Element (UCE) phylogenomic data were sequenced for all forms, both within and among sites, and a phylogeny was inferred. Informed by phylogeny, species delimitation was based on monophyly, absence of within-clade sympatry, and a subjective degree of morphological uniformity. UCE phylogenomic results for 130 specimens were complemented by analysis of mitochondrial COI (DNA barcode) data for an expanded taxon set. The resulting taxonomy augments the number of known species in the New World from 3 to 57. We describe and name 31 new species, and 23 species are assigned morphospecies codes pending improved specimen coverage. Queens may be fully alate or brachypterous, and there is a wide variety of intercaste female forms. 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.
MOLECULAR PHYLOGENETICS, PHYLOGENOMICS, AND PHYLOGEOGRAPHY
The millipede family Xystodesmidae includes 486 species distributed primarily in temperate deciduous forests in North America and East Asia. Species diversity of the family is greatest in the Appalachian Mountains of the eastern United States, with 188 species. Although the group includes notable taxa such as those that are bioluminescent and others that display Müllerian mimicry, producing up to 600 mg of cyanide, basic alpha-taxonomy of the group is woefully incomplete and more than 50 species remain undescribed in the Appalachian Mountains alone. In order to establish a robust phylogenetic foundation for addressing compelling evolutionary questions and describing species diversity, we assembled the largest species phylogeny (in terms of species sampling) to date in the Diplopoda. We sampled 49 genera (out of 57) and 247 of the species in the family Xystodesmidae, recollecting fresh material from historical type localities and discovering new species in unexplored regions. Here, we present a phylogeny of the family using six genes (four mitochondrial and two nuclear) and include pivotal taxa omitted from previous studies including Nannaria, Erdelyia, taxa from East Asia, and 10 new species. We show that 6 of the 11 tribes are monophyletic, and that the family is paraphyletic with respect to the Euryuridae and Eurymerodesmidae. Prior supraspecific classification is in part inconsistent with the phylogeny and convergent evolution has caused artificial genera to be proposed. Subspecific classification is likewise incongruent with phylogeny and subspecies are consistently not sister to conspecifics. The phylogeny is used as a basis to update the classification of the family, diagnose monophyletic groups, and to inform species hypotheses.
Automated insect identification systems have been explored for more than two decades but have only recently started to take advantage of powerful and versatile convolutional neural networks (CNNs). While typical CNN applications still require large training image datasets with hundreds of images per taxon, pretrained CNNs recently have been shown to be highly accurate, while being trained on much smaller datasets. We here evaluate the performance of CNN-based machine learning approaches in identifying three curated species-level dorsal habitus datasets for Miridae, the plant bugs. Miridae are of economic importance, but species-level identifications are challenging and typically rely on information other than dorsal habitus (e.g., host plants, locality, genitalic structures). Each dataset contained 2–6 species and 126–246 images in total, with a mean of only 32 images per species for the most difficult dataset. We find that closely related species of plant bugs can be identified with 80–90% accuracy based on their dorsal habitus alone. The pretrained CNN performed 10–20% better than a taxon expert who had access to the same dorsal habitus images. We find that feature extraction protocols (selection and combination of blocks of CNN layers) impact identification accuracy much more than the classifying mechanism (support vector machine and deep neural network classifiers). While our network has much lower accuracy on photographs of live insects (62%), overall results confirm that a pretrained CNN can be straightforwardly adapted to collection-based images for a new taxonomic group and successfully extract relevant features to classify insect species.
Sepidiini is a speciose tribe of desert-inhabiting darkling beetles, which contains a number of poorly defined taxonomic groups and is in need of revision at all taxonomic levels. In this study, two previously unrecognized lineages were discovered, based on morphological traits, among the extremely speciose genera Psammodes Kirby, 1819 (164 species and subspecies) and Ocnodes Fåhraeus, 1870 (144 species and subspecies), namely the Psammodes spinosus species-group and Ocnodes humeralis species-group. In order to test their phylogenetic placement, a phylogeny of the tribe was reconstructed based on analyses of DNA sequences from six nonoverlapping genetic loci (CAD, wg, COI JP, COI BC, COII, and 28S) using Bayesian and maximum likelihood inference methods. The aforementioned, morphologically defined, species-groups were recovered as distinct and well-supported lineages within Molurina + Phanerotomeina and are interpreted as independent genera, respectively, Tibiocnodes Gearner & Kamiński gen. nov. and Tuberocnodes Gearner & Kamiński gen. nov. A new species, Tuberocnodes synhimboides Gearner & Kamiński sp. nov., is also described. Furthermore, as the recovered phylogenetic placement of Tibiocnodes and Tuberocnodes undermines the monophyly of Molurina and Phanerotomeina, an analysis of the available diagnostic characters for those subtribes is also performed. As a consequence, Phanerotomeina is considered as a synonym of the newly redefined Molurina sens. nov. Finally, spectrograms of vibrations produced by substrate tapping of two Molurina species, Toktokkus vialis (Burchell, 1822) and T. synhimboides, are presented.
Recent bumble bee declines have made it increasingly important to resolve the status of contentious species for conservation purposes. Some of the taxa found to be threatened are the often rare socially parasitic bumble bees. Among these, the socially parasitic bumble bee, Bombus flavidus Eversmann, has uncertain species status. Although multiple separate species allied with B. flavidus have been suggested, until recently, recognition of two species, a Nearctic Bombus fernaldae (Franklin) and Palearctic B. flavidus, was favored. Limited genetic data, however, suggested that even these could be a single widespread species. We addressed the species status of this lineage using an integrative taxonomic approach, combining cytochrome oxidase I (COI) and nuclear sequencing, wing morphometrics, and secretions used for mate attraction, and explored patterns of color polymorphism that have previously confounded taxonomy in this lineage. Our results support the conspecificity of fernaldae and flavidus; however, we revealed a distinct population within this broader species confined to eastern North America. This makes the distribution of the social parasite B. flavidus the broadest of any bumble bee, broader than the known distribution of any nonparasitic bumble bee species. Color polymorphisms are retained across the range of the species, but may be influenced by local mimicry complexes. Following these results, B. flavidusEversmann, 1852 is synonymized with Bombus fernaldae (Franklin, 1911) syn. nov. and a subspecific status, Bombus flavidus appalachiensisssp. nov., is assigned to the lineage ranging from the Appalachians to the eastern boreal regions of the United States and far southeastern Canada.
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