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Engineering strain critically affects the properties of materials and has extensive applications in semiconductors and quantum systems. However, the deployment of strain-engineered nanocatalysts faces challenges, in particular in maintaining highly strained nanocrystals under reaction conditions. Here, we introduce a morphology-dependent effect that stabilizes surface strain even under harsh reaction conditions. Using four-dimensional scanning transmission electron microscopy (4D-STEM), we found that cube-shaped core-shell Au@Pd nanoparticles with sharp-edged morphologies sustain coherent heteroepitaxial interfaces with larger critical thicknesses than morphologies with rounded edges. This configuration inhibits dislocation nucleation due to reduced shear stress at corners, as indicated by molecular dynamics simulations. A Suzuki-type cross-coupling reaction shows that our approach achieves a fourfold increase in activity over conventional nanocatalysts, owing to the enhanced stability of surface strain. These findings contribute to advancing the development of advanced nanocatalysts and indicate broader applications for strain engineering in various fields. 

A new genus and species of halictine bees (Halictinae: Halictini: Mexalictina) is described and figured from a mid-elevation forest in northwestern Costa Rica.Meliamelitta vulcanusgen. and sp. n. is allied toMexalictusEickwort but differs in the structure of the labral basal elevation, the obtuse epistomal sulcus, the elongate mandibles, the pectinate inner metatibial spur, the unique pterostigma, and the sculpturing of the basal area of the propodeum, among other features. A key is appended to the genera and subgenera of Mesoamerican, Central American, and Caribbean Halictinae to facilitate the recognition of the genus. 

Taxonomic notes are presented for the exclusively cleptoparasitic halictine bee subtribe Sphecodina (Halictinae: Halictini). Keys are presented to the Western and Eastern Hemisphere genera of Sphecondina. In the New World fauna, the genusMelissocleptisGonçalves is considered a subgenus ofAustrosphecodesMicheners. l., and the following species transferred:Austrosphecodes(Melissocleptis)albifacies(Gibbs),A. (M.)capriciosus(Schrottky),A. (M.)coriae(Moure & Hurd),A. (M.)diablotinus(Gibbs),A. (M.)genaroi(Engel),A. (M.)nigritus(Ashmead),A. (M.)tainoi(Engel),A. (M.)variabilis(Schrottky) comb. n. A key is provided to the subgenera ofMicrosphecodesEickwort & Stages. l., withTrichosphecodessubgen. n., established for those species with elongate ocular setae. Keys are also presented for the species ofMicrosphecodes s. str. andTrichosphecodes, along with the descriptions of the speciesMicrosphecodes(Microsphecodes)eickwortisp. n.,M. (M.)multirugosussp. n.,M. (M.)quechuasp. n., andM. (Trichosphecodes)trichophthalmussp. n. The Brazilian speciesNesosphecodes depressusGonçalves is transferred toNotoclopsgen. n., resulting in the new combinationNotoclops depressus(Gonçalves) comb. n. A key is presented to New World subgenera ofSphecodesLatreille, with the following new or resurrected groups:ProteranerRobertson,DrepaniumRobertson,SphecodiumRobertson,Asphecodiumsubgen. n., andBoreosphecodessubgen. n. The following new species are described among New WorldSphecodes:Sphecodes(Asphecodium)brevisulcatussp. n.,S. (Sphecodium)eustaurossp. n.,S. (S.)electrumsp. n.,S. (Sphecodes)zacatuchesp. n. The genusCaenosphecodesgen. n. is proposed forSphecodes pseudoredivivusAstafurova & Proshchalykin andS. redivivusBlüthgen, differing fromSphecodesby the elongate free part of the marginal cell, in this respect resembling New WorldMicrosphecodes. This results in the combinationsCaenosphecodes pseudoredivivus(Astafurova & Proshchalykin),C.sauteri(Meyer),C. simlaensis(Blüthgen), andC. redivivus(Blüthgen) comb. n. The currently employed characters for subgenera ofEupetersiaBlüthgens. l. fail to distinguish the groups. Accordingly, the key to subgenera is revised and the species newly organized as to subgenera.Cephalosphecodessubgen. n. is established forEupetersia macrocephalaPauly andE.mandibulataBlüthgen,Xanthocleptissubgen. n. is proposed forE.reticulata(Benoist), andPollinicleptissubgen. n. is erected forE.nathaniBaker,E.malayensis(Blüthgen),E.sabahensisPauly, andE.singaporensisPauly. A new species ofNesoeupetersia,E. dnopherasp. n., is described from Sabah, Malaysia and a tentative key provided to species of the subgenus.ThrausmusBuysson andCallosphecodesFriese are treated as independent genera, and the latter considered close toMelittocleptesgen. n., withMelittocleptes insularis(Smith) comb. n. as type species. A key is presented to Old World subgenera ofSphecodes, with the following new or resurrected groups:Proteraneropsissubgen. n.,Paradrepaniumsubgen. n.,Eusphecodessubgen. n.,SabulicolaVerhoeff,Caenocleptessubgen. n.,Xystoclopssubgen. n.,Callocleptessubgen. n., andNomiocleptessubgen. n. 

Two new subgenera are established for enigmatic species of African small carpenter bees, genusCeratinaLatreille (Xylocopinae: Ceratinini).Ceratina foveiferaStrand is most similar toCopoceratinaTerzo & Pauly but differs in integumental coloration and sculpturing and absence of supraclypeal ridges, and is here classified inXestoceratinasubgen. n.Ceratina labrosaFriese is similar toCeratinas. str. andEuceratinaHirashima, Moure, & Daly but differs by the structure of the metasomal terga and male genitalia, and is placed inAlloceratinasubgen. n. 

A system of subgenera is newly proposed for the diverse cuckoo bee genusTriepeolusRobertson (Epeolini: Thalestriina).Eurepeolussubgen. n. is proposed forTriepeolus tristis(Smith) andT.ventralis(Meade-Waldo), together spanning the Palaearctic, whileMesepeolussubgen. n. is established forT.epeolurusRightmyer for a distinctiveEpeolus-like group found in Mesoamerica. 

A new Palearctic species of the cleptoparasitic bee genusDioxysLepeletier & Audinet-Serville (Megachilinae: Dioxyini) is described and figured from southern Spain.Dioxys falsificussp. n. is most similar toD.pumilusGerstäcker, a species that occupies areas more easterly around the Mediterranean (at least from Sardinia eastward and potentially in eastern Morocco eastward). It is possible that historical records ofD.pumilusfrom southern Spain apply toD.falsificus. A revised key is provided to the genera of Dioxyini, and the South AfricanDioxoides alataMichener is transferred toNotodioxytesgen.n. 

Three new species of the cosmopolitan bee genusAnthophoraLatreille are described and figured from North America, all of the subgenusAnthophoroidesCockerell & Cockerell and all based on a series of females and males.Anthophora(Anthophoroides)buchmannisp. n. from Arizona, USA and Sonora, Mexico;A. (A.)cinerulasp. n. from California, Nevada, Utah, and Arizona, USA; whileA. (A.)kellieaesp. n. is recorded from southern California and Arizona, USA and Baja California, Mexico. An illustrated key is presented to the species ofAnthophoroides. 

Two new species of the scolebythid wasp genusClystopsenellaKieffer (Scolebythidae: Scolebythinae) are described and figured.Clystopsenella mayasp. n., is reported from Belize, representing the northernmost extant occurrence for the genus.Clystopsenella kampasp. n., is described from the southwestern Amazonian region of Madre de Dios, Peru, and intermingles traits of bothC.pacificaLepeco & Melo andC.longiventrisKieffer. A revised key is presented to the species of the genus. 

The self-assembly of shape-anisotropic nanocrystals into large-scale structures is a versatile and scalable approach to creating multifunctional materials. The tetrahedral geometry is ubiquitous in natural and manmade materials, yet regular tetrahedra present a formidable challenge in understanding their self-assembly behavior as they do not tile space. Here, we report diverse supracrystals from gold nanotetrahedra including the quasicrystal (QC) and the dimer packing predicted more than a decade ago and hitherto unknown phases. We solve the complex three-dimensional (3D) structure of the QC by a combination of electron microscopy, tomography, and synchrotron X-ray scattering. Nanotetrahedron vertex sharpness, surface ligands, and assembly conditions work in concert to regulate supracrystal structure. We also discover that the surface curvature of supracrystals can induce structural changes of the QC tiling and eventually, for small supracrystals with high curvature, stabilize a hexagonal approximant. Our findings bridge the gap between computational design and experimental realization of soft matter assemblies and demonstrate the importance of accurate control over nanocrystal attributes and the assembly conditions to realize increasingly complex nanopolyhedron supracrystals.