Royal Ontario Museum

Six potential Ca‐Mg‐Fe carbonate reference materials were assessed for oxygen and carbon isotope ratios homogeneity by secondary ion mass spectrometry (SIMS). This new suite includes three dolomites (Tucka‐22, M9548.2, Eugui) and one ankerite (WPA‐177‐2) with Fe# ranging from 0.0004 to 0.3429, one magnesite (M21350.2) with Fe# = 0.0099 and one siderite (Vizille‐1) with Fe# = 0.6152. The six materials were split into 128 to 2048 metrologically identical aliquots, each containing roughly 100 mg of sample. In this study, we report a detailed characterisation of the split materials for their major and minor chemical element compositions using electron probe microanalysis (EPMA), mineralogical compositions using X‐ray diffraction (XRD), oxygen and carbon isotope values determined in three independent gas‐source isotope ratio mass spectrometry (GS‐IRMS) laboratories. The repeatability of our SIMS measurements varied from ± 0.15 to ± 0.31‰ (1 standard deviation, 1 s ) for δ 18 O and from ± 0.29 to ± 0.71‰ (1 s ) for δ 13 C. These six carbonate samples span a wide range in oxygen (δ 18 O VSMOW from 12.98 ± 0.09‰ to 26.92 ± 0.11‰, 1 standard error of the mean, 1SE) and carbon (δ 13 C VPDB from ‐11.74 ± 0.20‰ to 2.43 ± 0.06‰, 1SE) isotope ratios. Significant SIMS compositional matrix effects of +6.7‰ (for δ 18 O) and ‐3.2‰ (for δ 13 C) were observed along the dolomite‐ankerite solid‐solution series in the compositional range Fe# = 0.0004 to 0.3429. Similarly, large compositional matrix effects of +4.2‰ and ‐9.5‰ were observed for δ 18 O and δ 13 C, respectively, along the magnesite‐siderite solid‐solution series. This confirms the need for multiple matrix‐matched reference materials spanning across a wide range in chemical compositions in order to get accurate SIMS isotope ratios in carbonate minerals that form solid‐solutions. The Ca‐Mg‐Fe carbonate reference materials described in this study were produced in sufficient amounts to be available to the global geochemical community for years to come.

ABSTRACT Aim African freshwater fishes serve as important biogeographical indicators of geomorphological and hydrological history across the continent. However, research focusing on the phylogeny, biogeography and diversification of African fishes, particularly in central Africa, is relatively scarce. Here, we evaluate three geological hypotheses regarding the formation of the contemporary Congo basin: (1) the dominance of the Ogooué and Kouilou rivers along the western continental margin during the Cretaceous, (2) an eastward‐flowing Congo‐Zambezian system forming the Rufiji Delta during the Paleogene and (3) river basin capture resulting in the formation of the Lower Congo River during the Pliocene. To do this, we reconstructed the phylogeny of featherfin tetras of the genus Bryconaethiops using their mitochondrial genomes, estimated diversification chronology, and detected biogeographic transitions in Central Africa. Location Afrotropical rivers of Nilo‐Sudan, Lower Guinea, Congo and Malagarasi‐Tanganyika. Time Period Oligocene, Neogene and Quaternary. Taxon Bryconaethiops (Teleostei: Characiformes: Alestidae). Methods Analysis of a molecular matrix of complete mitochondrial genomes comprising 13 protein‐coding genes totaling 14,869 bp for 36 Bryconaethiops and related alestid taxa. Phylogenetic analyses included maximum likelihood, Bayesian fossil calibration, and parametric biogeographic reconstructions. Support for generic monophyly was evaluated using internal and external anatomy with microcomputed tomography (μCT) and conventional morphometric/meristic analyses. Data from museum specimens provided updated distributional ranges for each Bryconaethiops species. Results Time‐calibrated phylogenetic and biogeographic analyses suggest initial diversification of Bryconaethiops occurred in Lower Guinea during the Oligocene ( ca. 25 Ma), followed by transitions to the Nilo‐Sudan and Middle Congo regions during the Early Miocene ( ca. 19–17 Ma). Three distinct Pleistocene dispersal events to the Lower Congo ( ca. 0.7–0.05 Ma) and three to the Upper Congo and Malagarasi of Tanganyika ( ca. 1.5–0.1 Ma) were detected. Morphological analysis reveals four generic synapomorphies associated with modification of the upper and lower jaws, dentition and elongation of dorsal‐fin lepidotrichia, in addition to evidence for revalidation of B. mocquardianus (Thominot, 1886) from Atlantic coastal rivers of the eastern Gulf of Guinea. Main Conclusions Genetic and biogeographical analysis of Bryconaethiops supports the hypothesis that an expansive, centrally situated lowland proto‐Congo was captured by the modern Lower Congo during the Plio‐Pleistocene. Sympatric occurrences of sister taxa point to a complex scenario of allopatric speciation followed by secondary contact and/or resource partitioning across the Congo basin.

The long-legged bat (Macrophyllum macrophyllum) is widely distributed in the continental Neotropics, but poorly known because it is not commonly caught in mist nets. Available data suggest that this species is closely associated with water where it forages for insect prey. We compiled the first comprehensive molecular dataset assembled for the species, spanning its entire distributional range to investigate if the phylogeography of this monotypic genus is associated with the hydrographic drainage, ecosystem regions, or genetic clustering in Central and South America. To survey under sampled areas, fieldwork was conducted in the Brazilian Pantanal and Cerrado targeting the search for riverine roost sites of Macrophyllum. A literature review was also done to summarize roosting information for the species. New sequences of the mitochondrial cytochrome b gene were generated for tissue samples from Brazil and in museum collections. Phylogenetic trees were constructed using both maximum likelihood and Bayesian inference methods and a haplotype network was used to analyze population structure. Our phylogenetic results identified five geographic lineages of Macrophyllum from (1) the western Cerrado, (2) eastern Cerrado and Pantanal, (3) Guianas, (4) Amazonia, and (5) Central America. However, the haplotype network in conjunction with the genetic clustering identified four populations with the eastern Cerrado and Pantanal grouping with the Guianas and the eastern part of Amazonia. The fieldwork in the Cerrado and Pantanal along with the literature review identified that about half of the roost sites for the long-legged bats were drainage culverts. There is geographic structuring in the mitochondrial data of Macrophyllum with Central America, western Cerrado, Pantanal, Guianas, and eastern Ecuador reciprocally monophyletic and well differentiated populations. However, the under sampled eastern Amazonia is poorly resolved in relation to the other areas. The long-legged bats seem to be relatively adaptable to certain levels of human disturbance and landscape development with man-made drainage culverts commonly used as roosting sites. Increased biodiversity surveys of bats in central Brazil are needed to fill in distributional gaps, such as the lower Amazon River basin, to resolve phylogeographic patterns of Macrophyllum in South America and better understand the potential of cryptic species in this monotypic genus.

Abstract Gold is one of the most studied metals in human history, yet more research is required to better understand the behavior of major, minor, and trace elements in native gold to advance our understanding of gold systems. The Superior craton in Ontario, Canada, provides an excellent study area for gold systems because of the abundance and distribution of world class gold deposits. The present study constrains the geochemical signature of native gold using scanning electron microscopy-energy dispersive spectrometry, electron probe microanalysis, and laser ablation-inductively coupled plasma-microscopy to characterize 238 samples from 70 gold deposits and occurrences. Generally, Ag, Cu, and Hg occur over 100 ppm, with Sb, Pd, Cd, and Bi typically occurring as trace elements between 0.001 and 100 ppm. The geochemical signature of gold is variable at the craton scale, but it is consistent at the gold district scale. These spatially distinct trace element signatures are independent of local host rock and deposit types, with the exception of Pd, which suggests an affinity for gold from magmatic-hydrothermal deposits. The regional control on the Sb, Hg, Cd, and Cu in gold has implications for ore-forming processes and how these metals are sourced in gold deposits. These elemental signatures also have important practical applications for industry; for example, in using elemental vectors in exploration that reflect local gold composition and/or in metallurgical processing.

Abstract In spite of their important roles in many ecosystems, data regarding population structure and biogeographic patterns of leeches are scarce. To begin to address this knowledge gap, we herein perform a phylogeographic analysis of the North American medicinal leech, Macrobdella decora (Say, 1824). A total of 224 M. decora specimens were collected from 35 localities across large swaths of USA and Canada and covering most of the known range of the species. Using four loci (mitochondrial cytochrome c oxidase subunit I [COI] and NADH dehydrogenase I [ND1], as well as nuclear 18S rRNA [18S] and 28S rRNA [28S]), we construct phylogenetic trees using several optimality criteria and superimpose geographic patterns onto the trees in order to tease out any potential structure among the populations. Rather surprisingly, given the large geographic range of the species and abundance of potential geographic barriers to gene flow, the analyses showed a conspicuous lack of structure among the different populations of M. decora. However, an AMOVA did show statistically significant differences between the genetic variation within populations and between populations (COI: FST = 0.65412, p < .00001; ND1: FST = 0.69245, p < .00001), which was largely driven by only 6 out of the 35 populations, and indicated a potential barrier for dispersal across the Appalachian Mountains. Finally, a Mantel test showed a weak, but significant, correlation between geographic distance and genetic distance (COI: r = 0.209, p = .027; ND1: r = 0.1289, p = .030); however, this correlation was primarily driven by a single locality. The overall weak structure suggests that M. decora is panmictic throughout its range, and we discuss this in light of previous population level studies in both bloodfeeding and non‐bloodfeeding species, concluding that the lack of structure in M. decora might be due to its high capacity for dispersal via hosts.

Approximately 200 meteorites come from ~10 impact events on the surface of Mars, yet their pre-ejection locations are largely unknown. Here, we combine the results of diverse sets of observations and modeling to constrain the source craters for several groups of martian meteorites. We compute that ejection-paired groups of meteorites are derived from lava flows within the top 26 m of the surface. We link ejection-paired groups to specific source craters and geologic units, providing context for these important samples, reconciling microscopic observations with remote sensing records, and demonstrating the potential to constrain the ages of their source geologic units. Furthermore, we show that there are craters that may have produced martian meteorites not represented in the world's meteorite collections that have yet to be discovered.

A new, distinctively short-bodied giraffe catfish of Parauchenoglanis is described from the Ndzaa River, a small left-bank tributary of the Mfimi-Lukenie basin in the Central basin of the Congo River in the Democratic Republic of the Congo. The new species can be distinguished from all congeners by having 29 or fewer (vs. 33 or more) total vertebrae. It can further be distinguished from all congeners, except Parauchenoglanis zebratus Sithole et al., 2023 and Parauchenoglanis ngamensis (Boulenger 1911), by having 13 or 14 (vs. 16 or more) pre-anal vertebrae. The species is endemic to the Mfimi River basin, where it has been collected mainly in blackwater tributaries.

Abstract. neighboring countries. Recently, an increase in biological surveys and access to natural preserves has led to a better understanding of species distributions in Nicaragua and across Central America. Here, we provide new departmental records for three species of didelphid, 18 chiropterans (Phyllostomidae, Molossidae, Vespertilionidae), one geomyid, and one mustelid from 21 sites across the country. This work underscores the need for additional sampling across Nicaragua to fill gaps in the known distribution of many species. This information can facilitate or inform conservation actions in established and proposed preserves in Nicaragua.