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An antitropical pattern is characterized by the occurrence of closely related taxa south and north of the tropics but absent or uncommonly represented closer to the equator, in contrast to most taxa, which tend to have their highest diversity in the tropical regions. We investigate the antitropical distribution of eucerine bees with the aim of contributing to the characterization and understanding of this pattern.

All continents except Antarctica and Australia.

Eucerine bees (Hymenoptera: Apidae: Eucerinae).

We carried out phylogenomic dating under two different clock models and used multiple strategies to vary matrix composition, evaluating the overlapping of divergence times estimated across models using Bhattacharyya coefficients. Lastly, we reconstructed the biogeographic history of eucerine bees using a Bayesian implementation of the DEC model.

Eucerinae is estimated to have started diversifying during the Palaeocene, with all its tribes originating during the Palaeocene/Eocene transition in southern South America. At least two range expansions happened into North America before the full closure of the Isthmus of Panama. We show that divergence between closely related groups with disjunct distributions would have happened in periods when the climate favoured the expansion of open habitats and became isolated when the forests were re‐established.

We describe the early diversification of eucerine bees, revealing an intimate association with southern South America. Events of range evolution of Eucerinae were likely affected by periods of global cooling and aridification, and palaeoclimatic and vegetational conditions probably have been more relevant to the formation of the antitropical distribution of Eucerinae than the consolidation of the Isthmus of Panama connecting the Americas. We also demonstrate that most uncertainty in divergence time estimation is not due to the amount of molecular data being used, but more likely other factors like fossil calibrations and violations of clock models.

 

The family Mutillidae (Hymenoptera) is a species‐rich group of aculeate wasps that occur worldwide. The higher‐level classification of the family has historically been controversial due, in part, to the extreme sexual dimorphism exhibited by these insects and their morphological similarity to other wasp taxa that also have apterous females. Modern hypotheses on the internal higher classification of Mutillidae have been exclusively based on morphology and, further, they include Myrmosinae as a mutillid subfamily. In contrast, several molecular‐based family‐level studies of Aculeata recovered Myrmosinae as a nonmutillid taxon. To test the validity of these morphology‐based classifications and the phylogenetic placement of the controversial taxon Myrmosinae, a phylogenomic study of Mutillidae was conducted using ultraconserved elements (UCEs). All currently recognized subfamilies and tribes of Mutillidae were represented in this study using 140 ingroup taxa. The maximum likelihood criterion (ML) and the maximum parsimony criterion (MP) were used to infer the phylogenetic relationships within the family and related taxa using an aligned data set of 238,764 characters; the topologies of these respective analyses were largely congruent. The modern higher classification of Mutillidae, based on morphology, is largely congruent with the phylogenomic results of this study at the subfamily level, whereas the tribal classification is poorly supported. The subfamily Myrmosinae was recovered as sister to Sapygidae in the ML analysis and sister to Sapygidae + Pompilidae in the MP analysis; it is consequently raised to the family level, Myrmosidae,stat.nov.The two constituent tribes of Myrmosidae are raised to the subfamily level, Kudakrumiinae,stat.nov., and Myrmosinae,stat.nov.All four recognized tribes of Mutillinae were found to be non‐monophyletic; three additional mutilline clades were recovered in addition to Ctenotillini, Mutillini, Smicromyrmini, and Trogaspidiini sensu stricto. Three new tribes are erected for members of these clades: Pristomutillini Waldren,trib.nov., Psammothermini Waldren,trib.nov., and Zeugomutillini Waldren,trib.nov.All three recognized tribes of Sphaeropthalminae were found to be non‐monophyletic; six additional sphaeropthalmine clades were recovered in addition to Dasymutillini, Pseudomethocini, and Sphaeropthalmini sensu stricto. The subtribe Ephutina of Mutillinae: Mutillini was found to be polyphyletic, with theEphutagenus‐group recovered within Sphaeropthalminae and theOdontomutillagenus‐group recovered as sister to Myrmillinae + Mutillinae. Consequently, the subtribe Ephutina is transferred from Mutillinae: Mutillini and is raised to a tribe within Sphaeropthalminae, Ephutini,stat.nov.Further, the taxon Odontomutillinae,stat.nov., is raised from a synonym of Ephutina to the subfamily level. The sphaeropthalmine tribe Pseudomethocini was found to be polyphyletic, with the subtribe Euspinoliina recovered as a separate clade in Sphaeropthalminae; consequently, Euspinoliina is raised to a tribe, Euspinoliini,stat.nov., in Sphaeropthalminae. The dasylabrine tribe Apteromutillini was recovered within Dasylabrini and is proposed as a new synonym of Dasylabrinae. Finally, dating analyses were conducted to infer the ages of the Pompiloidea families (Mutillidae, Myrmosidae, Pompilidae, and Sapygidae) and the ages of the Mutillidae subfamilies and tribes.

 

Despite recent advances in phylogenomics, the early evolution of the largest bee family, Apidae, remains uncertain, hindering efforts to understand the history of Apidae and establish a robust comparative framework. Confirming the position of Anthophorinae—a diverse, globally distributed lineage of apid bees—has been particularly problematic, with the subfamily recovered in various conflicting positions, including as sister to all other Apidae or to the cleptoparasitic Nomadinae. We aimed to resolve relationships in Apidae and Anthophorinae by combining dense taxon sampling, with rigorous phylogenomic analysis of a dataset consisting of ultraconserved elements (UCEs) acquired from multiple sources, including low-coverage genomes. Across a diverse set of analyses, including both concatenation and species tree approaches, and numerous permutations designed to account for systematic biases, Anthophorinae was consistently recovered as the sister group to all remaining Apidae, with Nomadinae sister to (Apinae, [Xylocopinae, Eucerinae]). However, several alternative support metrics (concordance factors, quartet sampling, and gene genealogy interrogation) indicate that this result should be treated with caution. Within Anthophorinae, all genera were recovered as monophyletic, following synonymization of Varthemapistra with Habrophorula. Our results demonstrate the value of dense taxon sampling in bee phylogenomics research and how implementing diverse analytical strategies is important for fully evaluating results at difficult nodes.

 

Abstract Coloration is an important phenotypic trait for taxonomic studies and has been widely used for identifying insect species and populations. However, coloration can be a poor diagnostic character for insect species that exhibit high polymorphism in this trait, which can lead to over-splitting of taxonomic units. In orchid bees, color variation has been interpreted by different taxonomists as either polymorphism associated with Müllerian mimicry complexes or diagnostic traits for species identification. Despite this uncertainty, integrative approaches that incorporate multiple independent datasets to test the validity of hair coloration as a character that identifies independent evolutionary units have not been used. Here, we use phylogenomic data from Ultraconserved Elements (UCEs) to explore whether color phenotypes in the widespread orchid bee species complexes Eulaema meriana and Eulaema bombiformis (Hymenoptera: Apidae: Euglossini) correspond to independent lineages or polymorphic trait variation within species. We find that lineages within both species are structured according to geography and that color morphs are generally unassociated with evolutionarily independent groups except for populations located in the Atlantic Forest of Brazil. We conclude that there is compelling evidence that E. atleticana and E. niveofasciata are subspecies of E. meriana and E. bombiformis, respectively, and not different species as previously suggested. Therefore, we recognize Eulaema meriana atleticanacomb. n. and Eulaema bombiformis niveofasciatacomb. n. and discuss their morphological characteristics. We make recommendations on the use of color traits for orchid bee taxonomy and discuss the significance of subspecies as evolutionary units relevant for conservation efforts. 

Ptilothrix Cresson is a genus of New World bees with an amphitropical distribution. Like other genera in the tribe Emphorini, Ptilothrix have narrow pollen preferences. These solitary ground-nesting bees exhibit a remarkable nesting behavior in which females carry water from ponds to facilitate the excavation of the hard soil where they nest. With 16 described species, there are few taxonomic studies and, before this work, a lack of taxonomic treatments for the species in North America. Thus, in this study we revised and recognized four species for the region: Ptilothrix bombiformis Cresson, Ptilothrix sumichrasti Cresson, Ptilothrix chiricahua Florez-Gomez & Danforth, sp. nov. and Ptilothrix zacateca Florez-Gomez & Danforth, sp. nov. We describe and illustrate males and females of the two new species. We also present diagnoses for the four species, a key to identify them, and a map of their geographic distributions. 

Species delimitation is a rich scientific field that often uses different sources of data to identify independently evolving lineages that might be recognized as species. Here, we use an integrative approach based on morphometrics, COI-barcoding, and phylogenomics using ultraconserved elements (UCEs) to investigate whether the orchid bee species Eulaema cingulata (Fabricius, 1804) and E. pseudocingulata Oliveira, 2006 represent a single variable taxon or two different species. We analyzed 126 specimens across the geographical range of these nominal species to test species hypotheses using the general lineage concept. We found substantial overlap in wing and head morphometrics, and both taxa form one phylogenetic lineage based on COI mitochondrial and UCE data. Our results support the recognition of both forms as members of the same evolutionary unit and E. pseudocingulata is herein recognized as a junior synonym of E. cingulata . 

As part of a broader treatment of Eucerini systematics, a new genus and a new subgenus are described to accommodate previously described species. Savannychapis gen. n. is described to accommodate Gaesischia interrupta Urban 1989, originally described as a species of Gaesischia (Gaesischiana) Michener et al. 1955, and Gaesischia (Gaesischioides) subgen. n. to accommodate Gaesischia hyptidis (Ducke 1910), previously included in Gaesischia s. str. Michener et al. 1955 and G. (Agaesischia) Moure & Michener 1955. These new taxa are only known in the South American dry diagonal, a set of open vegetation biomes of central-eastern South America.