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  Widespread concern about the “decline of taxonomy” has motivated calls to action to re-invigorate the field by enhancing taxonomic training, along with increasing taxonomy funding and positions, improving citation rates, and describing species more rapidly. Taxonomic training has historically been apprentice style, with individuals training for years under expert guidance. This approach offers a rich learning experience but inherently limits trainee number and relies on students’ earlier exposure to taxonomy. We describe a scaled-up taxonomic training model using a Course-based Undergraduate Research Experience (CURE) to provide early taxonomy research experience and broadly applicable scientific research skills. Results from a 45-student taxonomy-focused course conducted concurrently at 2 universities resulted in increased interest in taxonomic revisions and ability to explain taxonomic concepts, with one-third of students developing more interest in taxonomic careers. General science skill development was high when compared to a large sample of other CURE courses. The research focus of the course was taxonomic revision of the ant genus Nylanderia in Meso-America; students worked with instructors to delimit and describe new species. Here, we present 4 newly described species: Nylanderia ambulator, sp. nov. Nylanderia aurantia, sp. nov., Nylanderia collaborans, sp. nov., and Nylanderia maximon, sp. nov., with an additional 13 putative species noted for further revisionary work. This expanded taxonomic training model combines hands-on research experience with peer-learning and caters to students with minimal exposure to taxonomy. As a result, this approach broadens recruitment to more diverse audiences and results in enhanced awareness of and appreciation for taxonomy. 

Globally, potentially hundreds of Nylanderia species remain undescribed, hidden within several broadly distributed complexes of morphologically cryptic species. By integrating phylogenomics, geography, and morphology, we describe eight new Nylanderia species from southern Mexico and Mesoamerica, increasing the total number of known species in the genus to 131. In the Americas, Nylanderia is divided into two distantly related clades: American Clade I (AC1) and American Clade II (AC2). Within AC1, Nylanderia austroccidua (Trager) was originally described as a widespread and morphologically variable species distributed from Utah to Costa Rica. This species was diagnosed by a slight concavity in the anterior face of the pronotum and varying degrees of fine cuticular microsculpturing across the body that causes blue cuticular iridescence under microscopic examination. Using Ultraconserved Elements (UCEs) for molecular phylogenetic analysis, we found that taxa matching the original description of N. austroccidua are paraphyletic with respect to Nearctic Nylanderia species. We also found that AC1 includes a Neotropical subclade extending into Mesoamerica, the distribution of which overlaps with AC2, which is exclusively Neotropical. Along with an updated description of N. austroccidua, we also describe the following new species belonging to clade AC1: N. breviscapa, sp. nov., N. contraria, sp. nov., N. lazulina, sp. nov., N. luceata, sp. nov., N. mendax sp. nov., N. mosaica sp. nov., N. polita sp. nov., and N. usul, sp. nov. A dichotomous key and images of the worker caste of these species are included and, where available, images of queens and males are provided.  

In many multiobject tracking applications, including radar and sonar tracking, after prefiltering the received signal, measurement data is typically structured in cells. The cells, e.g., represent different range and bearing values. However, conventional multiobject tracking methods use so-called point measurements. Point measurements are provided by a preprocessing stage that applies a threshold or detector and breaks up the cell’s structure by converting cell indexes into, e.g., range and bearing measurements. We here propose a Bayesian multiobject tracking method that processes measurements that have been thresholded but are still cell-structured. We first derive a likelihood function that systematically incorporates an adjustable detection threshold which makes it possible to control the number of cell measurements. We then propose a Poisson Multi-Bernoulli (PMB) filter based on the likelihood function for cell measurements. Furthermore, we establish a link to the conventional point measurement model by deriving the likelihood function for point measurements with amplitude information (AM) and discuss the PMB filter that uses point measurements with AM. Our numerical results demonstrate the advantages of the proposed PMB filter for thresholded cell measurements compared to the conventional PMB filter for point measurements with and without AM. 

Abstract The classification of ants (Hymenoptera: Formicidae) has progressed in waves since the first 17 species were described by Linnaeus in the 1758 edition of Systema Naturae. Since then, over 18,000 species-rank names have accumulated for the global myrmecofauna, of which ~14,260 living and ~810 fossil species are valid. Here, we provide a synopsis of ant biodiversity and review the history and classification of the family, while highlighting the massive growth of the field in the new millennium. We observe that major transformation has occurred for ant classification due to advances in DNA sequencing technologies, model-based hypothesis testing, and imaging technologies. We therefore provide a revised and illustrated list of diagnostic character states for the higher clades of Formicidae, recognizing that vastly more work is to be done. To facilitate discussion and the systematic accumulation of evolutionary knowledge for the early evolution of the ants, we suggest an informal nomenclatural system for the higher clades of ants, based on names currently in use and a set of names that have been democratically selected by the authors. To guide future work on ant systematics, we summarize currently available databases and present perspectives on regions in need of biodiversity exploration, challenges facing the field, and the future of ant taxonomy. 

Abstract The ant genus Nylanderia Emery has a cosmopolitan distribution and includes 150 extant described species and subspecies, with potentially hundreds more undescribed. Global taxonomic revision has long been stalled by strong intra- and interspecific morphological variation, limited numbers of diagnostic characters, and dependence on infrequently collected male specimens for species description and identification. Taxonomy is further complicated by Nylanderia being one of the most frequently intercepted ant genera at ports of entry worldwide, and at least 15 globetrotting species have widespread and expanding ranges, making species-level diagnoses difficult. Three species complexes (‘bourbonica complex’, ‘fulva complex’, and ‘guatemalensis complex’) include globetrotting species. To elucidate the phylogenetic positions of these three complexes and delimit species boundaries within each, we used target enrichment of ultraconserved elements (UCEs) from 165 specimens representing 98 Nylanderia morphospecies worldwide. We also phased the UCEs, effectively doubling sample size and increasing population-level sampling. After recovering strong support for the monophyly of each complex, we extracted COI barcodes and SNPs from the UCE data and tested within-complex morphospecies hypotheses using three molecular delimitation methods (SODA, bPTP, and STACEY). This comparison revealed that most methods tended to over-split taxa, but results from STACEY were most consistent with our morphospecies hypotheses. Using these results, we recommend species boundaries that are conservative and most congruent across all methods. This work emphasizes the importance of integrative taxonomy for invasive species management, as globetrotting occurs independently across at least nine different lineages across Nylanderia. 

Abstract Nylanderia(Emery) is one of the world's most diverse ant genera, with 123 described species worldwide and hundreds more undescribed. Fifteen globetrotting or invasive species have widespread distributions and are often encountered outside their native ranges. A molecular approach to understanding the evolutionary history and to revision ofNylanderiataxonomy is needed because historical efforts based on morphology have proven insufficient to define major lineages and delimit species boundaries, especially where adventive species are concerned. To address these problems, we generated the first genus‐wide genomic dataset ofNylanderiausing ultraconserved elements (UCEs) to resolve the phylogeny of major lineages, determine the age and origin of the genus, and describe global biogeographical patterns. Sampling from seven biogeographical regions revealed a Southeast Asian origin ofNylanderiain the mid‐Eocene and four distinct biogeographical clades in the Nearctic, the Neotropics, the Afrotropics/Malagasy region, and Australasia. The Nearctic and Neotropical clades are distantly related, indicating two separate dispersal events to the Americas between the late Oligocene and early Miocene. We also addressed the problem of misidentification that has characterized species‐level taxonomy inNylanderiaas a result of limited morphological variation in the worker caste by evaluating the integrity of species boundaries in six of the most widespreadNylanderiaspecies. We sampled across ranges of species in theN. bourbonicacomplex (N. bourbonica(Forel) + N. vaga(Forel)), theN. fulvacomplex (N. fulva(Mayr) + N. pubens(Forel)), and theN. guatemalensiscomplex (N. guatemalensis(Forel) + N. steinheili(Forel)) to clarify their phylogenetic placement. Deep splits within these complexes suggest that some species names – specificallyN. bourbonicaandN. guatemalensis– each are applied to multiple cryptic species. In exhaustively samplingNylanderiadiversity in the West Indies, a ‘hot spot’ for invasive taxa, we found five adventive species among 22 in the region; many remain morphologically indistinguishable from one another, despite being distantly related. We stress that overcoming the taxonomic impediment through the use of molecular phylogeny and revisionary study is essential for conservation and invasive species management.