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1. Species delimitation and invasion history of the balsam woolly adelgid, Adelges ( Dreyfusia ) piceae (Hemiptera: Aphidoidea: Adelgidae), species complex

   https://doi.org/10.1111/syen.12456  

   Havill, Nathan P. ; Griffin, Brian P. ; Andersen, Jeremy C. ; Foottit, Robert G. ; Justesen, Mathias J. ; Caccone, Adalgisa ; D'Amico, Vincent ; Elkinton, Joseph S. ( October 2020 , Systematic Entomology)

   TheAdelges(Dreyfusia)piceae(Ratzeburg) species complex is a taxonomically unstable group of six species. Three of the species are cyclically parthenogenetic [Ad.nordmannianae(Eckstein),Ad.prelli(Grossmann), andAd.merkeri(Eichhorn)] and three are obligately asexual [Ad.piceae,Ad.schneideri(Börner), andAd.nebrodensis(Binazzi & Covassi)]. Some species are high‐impact pests of fir (Abies) trees, so stable species names are needed to communicate effectively about management. Therefore, to refine species delimitation, guided by a reconstruction of their biogeographic history, we genotyped adelgids from Europe, North America, and the Caucasus Mountains region with 19 microsatellite loci, sequenced the COI DNA barcoding region, and compared morphology. Discriminant analysis of principal components of microsatellite genotypes revealed four distinct genetic clusters. Two clusters were morphologically consistent withAd.nordmannianae. One of these clusters consisted of samples from the Caucasus Mountains and northern Turkey, and the other included samples from this region as well as from Europe and North America, whereAd.nordmannianaeis invasive. A third cluster was morphologically consistent withAd.piceae, and included individuals from Europe, where it is native, and North America, where it is invasive. In North America, the majority ofAd.piceaeindividuals were assigned to two geographically widespread clones, suggesting multiple introductions. The fourth cluster included individuals morphologically consistent withAd.prelliorAd.merkeri. However, based on genetic assignments, hybrid simulations, and approximate Bayesian computation, we find it likely that these are contemporary hybrids betweenAd.nordmannianaeandAd.piceaethat arose independently in Europe and North America, so we propose thatAd.prelliandAd.merkeriare invalid. Finally, we synonymiseAd.schneideri(syn.n.)withAd.nordmannianaeand designateAd.nebrodensisas subspeciesAd.piceae nebrodensis(stat.n.). Our revised taxonomy therefore recognises two species:Ad.nordmannianaeandAd.piceae, which we estimate to have diverged recently, during one of the last two interglacial periods. Finally, we comment on this species complex being in the midst of transition between sexual and asexual reproduction, a pattern that is probably common in Adelgidae.

    

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2. Molecular systematics of two sister clades, the Fusarium concolor and F. babinda species complexes, and the discovery of a novel microcycle macroconidium–producing species from South Africa

   https://doi.org/10.1080/00275514.2018.1526619  

   Jacobs-Venter, Adriaana ; Laraba, Imane ; Geiser, David M. ; Busman, Mark ; Vaughan, Martha M. ; Proctor, Robert H. ; McCormick, Susan P. ; O’Donnell, Kerry ( November 2018 , Mycologia)
3. Mitochondrial DNA and other lines of evidence clarify species diversity in the Peromyscus truei species group (Cricetidae: Neotominae)

   https://doi.org/10.1515/mammalia-2021-0146  

   Hernández-Canchola, Giovani ; León-Paniagua, Livia ; Esselstyn, Jacob A. ( January 2022 , Mammalia)

   Abstract Deer mice (genus Peromyscus ) are among the commonest small mammals in the Nearctic zoogeographic region. Nevertheless, systematic relationships are only partially settled and numerous taxonomic questions await resolution. For instance, researchers have found that some members of the Peromyscus truei species group contain high levels of genetic divergence that could indicate the presence of cryptic species. We analyzed the systematics and phylogenetic relationships of the P. truei group using new and previously published mitochondrial cytochrome b sequences. Our analyses verify several earlier conclusions, but we also detected new clades that deserve recognition. Considering their mitochondrial distinctiveness, allopatric ranges, and previously reported molecular, biochemical, chromosomal, morphological, and ecological differences, we elevate three previously described taxa to species. We support the recognition of two subgroupings. The first comprises P. gratus , P. truei , and possibly P. cf. martirensis and P. cf.  zapotecae . The second contains to P. amplus , P. attwateri , P. collinus , P. difficilis , P. felipensis , P. laceianus , P. nasutus , P. ochraventer , and P. pectoralis. Placement of P. bullatus will likely remain unknown until genetic data are available. Further research could improve our understanding of the evolutionary history of Peromyscus , but in some cases taxonomic issues must be resolved first. 

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4. Phylogenomic Delimitation of Morphologically Cryptic Species in Globetrotting Nylanderia (Hymenoptera: Formicidae) Species Complexes

   https://doi.org/10.1093/isd/ixab027  

   Williams, Jason L ; Zhang, Y Miles ; LaPolla, John S ; Schultz, Ted R ; Lucky, Andrea ( January 2022 , Insect Systematics and Diversity)

   Camacho, Gabriela P (Ed.)

   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. 

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5. Taxonomic revision of the Malagasy members of the Nesomyrmex angulatus species group using the automated morphological species delineation protocol NC-PART-clustering

   https://doi.org/10.7717/peerj.1796  

   Csősz, Sándor ; Fisher, Brian L. ( March 2016 , PeerJ)

   Background.Applying quantitative morphological approaches in systematics research is a promising way to discover cryptic biological diversity. Information obtained through twenty-first century science poses new challenges to taxonomy by offering the possibility of increased objectivity in independent and automated hypothesis formation. In recent years a number of promising new algorithmic approaches have been developed to recognize morphological diversity among insects based on multivariate morphometric analyses. These algorithms objectively delimit components in the data by automatically assigning objects into clusters.

   Method.In this paper, hypotheses on the diversity of the MalagasyNesomyrmex angulatusgroup are formulated via a highly automated protocol involving a fusion of two algorithms, (1) Nest Centroid clustering (NC clustering) and (2) Partitioning Algorithm based on Recursive Thresholding (PART). Both algorithms assign samples into clusters, making the class assignment results of different algorithms readily inferable. The results were tested by confirmatory cross-validated Linear Discriminant Analysis (LOOCV-LDA).

   Results.Here we reveal the diversity of a unique and largely unexplored fragment of the Malagasy ant fauna using NC-PART-clustering on continuous morphological data, an approach that brings increased objectivity to taxonomy. We describe eight morphologically distinct species, including seven new species:Nesomyrmex angulatus(Mayr, 1862),N. bidentatussp. n.,N. clypeatussp. n.,N. deviussp. n.,N. exiguussp. n.,N. fragilissp. n.,N. gracilissp. n., andN. hirtellussp. n.. An identification key for their worker castes using morphometric data is provided.

   Conclusions.Combining the dimensionality reduction feature of NC clustering with the assignment of samples into clusters by PART advances the automatization of morphometry-based alpha taxonomy.

    

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