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Abstract. Compound flooding, where the combination or successive occurrence of two or more flood drivers leads to a greater impact, can exacerbate the adverse consequences of flooding, particularly in coastal/estuarine regions. This paper reviews the practices and trends in coastal/estuarine compound flood research and synthesizes regional to global findings. Systematic review is employed to construct a literature database of 271 studies relevant to compound flooding in a coastal/estuarine context. This review explores the types of compound flood events, their mechanistic processes, and synthesizes terminology throughout the literature. Considered in the review are six flood drivers (fluvial, pluvial, coastal, groundwater, damming/dam failure, and tsunami) and five precursor events and environmental conditions (soil moisture, snow, temp/heat, fire, and drought). Furthermore, this review summarizes research methodology and study applications trends, and considers the influences of climate change and urban environments. Finally, this review highlights knowledge gaps in compound flood research and discusses the implications on future practices. Our five recommendations for compound flood research are: 1) adopt consistent terminology and approaches; 2) expand the geographic coverage of research; 3) pursue more inter-comparison projects; 4) develop modelling frameworks that better couple dynamic Earth systems; and 5) design urban and coastal infrastructure with compounding in mind. 

Abstract This study synthesizes the current understanding of the hydrological, impact, and adaptation processes underlying drought‐to‐flood events (i.e., consecutive drought and flood events), and how they interact. Based on an analysis of literature and a global assessment of historic cases, we show how drought can affect flood risk and assess under which circumstances drought‐to‐flood interactions can lead to increased or decreased risk. We make a distinction between hydrological, socio‐economic and adaptation processes. Hydrological processes include storage and runoff processes, which both seem to mostly play a role when the drought is a multiyear event and when the flood occurs during the drought. However, which process is dominant when and where, and how this is influenced by human intervention needs further research. Processes related to socio‐economic impacts have been studied less than hydrological processes, but in general, changes in vulnerability seem to play an important role in increasing or decreasing drought‐to‐flood impacts. Additionally, there is evidence of increased water quality problems due to drought‐to‐flood events, when compared to drought or flood events by themselves. Adaptation affects both hydrological (e.g., through groundwater extraction) or socio‐economic (e.g., influencing vulnerability) processes. There are many examples of adaptation, but there is limited evidence of when and where certain processes occur and why. Overall, research on drought‐to‐flood events is scarce. To increase our understanding of drought‐to‐flood events we need more comprehensive studies on the underlying hydrological, socio‐economic, and adaptation processes and their interactions, as well as the circumstances that lead to the dominance of certain processes. This article is categorized under:Science of Water > Hydrological ProcessesScience of Water > Water Extremes 

Abstract Carpenter ants in the genus Camponotus are large, conspicuous ants that are abundant and ecologically influential in many terrestrial ecosystems. The bicolored carpenter ant, Camponotus vicinus Mayr, is distributed across a wide range of elevations and latitudes in western North America, where it is a prominent scavenger and predator. Here, we present a high-quality genome assembly of C. vicinus from a sample collected in Sonoma County, California, near the type locality of the species. This genome assembly consists of 38 scaffolds spanning 302.74 Mb, with contig N50 of 15.9 Mb, scaffold N50 of 19.9 Mb, and BUSCO completeness of 99.2%. This genome sequence will be a valuable resource for exploring the evolutionary ecology of C. vicinus and carpenter ants generally. It also provides an important tool for clarifying cryptic diversity within the C. vicinus species complex, a genetically diverse set of populations, some of which are quite localized and of conservation interest. 

The arboreal ant genus Tetraponera is widely distributed in the Paleotropics. Five species groups were previously recognized in the Afrotropical region (including Madagascar), and two of these were revised. This paper provides a taxonomic treatment of the remaining species. A survey of the T. allaborans group on the African mainland leads to the recognition of fourteen species: T. clypeata (Emery) (= T. braunsi (Forel) syn. nov.); T. continua (Forel) (= T. claveaui (Santschi) syn. nov.); T. cortina sp. nov.; T. dispar sp. nov.; T. emeryi (Forel) (= T. braunsi durbanensis (Forel) syn. nov.); T. exactor sp. nov.; T. furtiva sp. nov.; T. gerdae (Stitz); T. liengmei (Forel); T. mayri (Forel); T. pedana sp. nov.; T. penzigi (Mayr) (= T. scotti Donisthorpe syn. nov. = T. zavattarii (Menozzi) syn. nov. = T. penzigi praestigiatrix Santschi syn. nov.); T. pumila sp. nov.; and T. tessmanni (Stitz). A full revision of the Malagasy species of the T. allaborans group is deferred, but the following new synonymy is established: T. hysterica (Forel) = T. hysterica inflata (Emery) syn. nov.; T. longula (Emery) = T. sahlbergii deplanata (Forel) syn. nov.; T. mandibularis (Emery) = T. flexuosa (Santschi) syn. nov.; T. morondaviensis (Forel) = T. arrogans (Santschi) syn. nov. = T. demens (Santschi) syn. nov. = T. hysterica dimidiata (Forel) syn. nov.; and T. sahlbergii = T. sahlbergii spuria (Forel) syn. nov. = T. plicatidens (Santschi) syn. nov. In the T. ambigua group the following synonymy is reinstated (syn. rev.): T. ambigua (Emery) = T. erythraea (Emery) = T. bifoveolata (Mayr) = T. angolensis Santschi; and T. ophthalmica (Emery) = T. unidens Santschi. A new species is described in the Madagascar-endemic T. grandidieri group: T. elegans sp. nov. Scrutiny of the T. natalensis group indicates the occurrence of ten species: T. andrei (Mayr), T. anthracina (Santschi), T. caffra (Santschi), T. insularis sp. nov., T. kosi sp. nov., T. mocquerysi (André), T. natalensis (F. Smith), T. redacta sp. nov., T. schulthessi (Santschi), and T. setosa sp. nov. T. insularis is known only from Madagascar, while the other nine species are confined to the African mainland. The following new synonymy is proposed for the T. natalensis group (senior synonym cited first): T. anthracina = T. poultoni Donisthorpe syn. nov. = T. triangularis (Stitz) syn. nov.; T. mocquerysi = T. mocquerysi biozellata (Karavaiev) syn. nov. = T. mocquerysi elongata (Stitz) syn. nov. = T. emacerata (Santschi) syn. nov. = T. triangularis illota (Santschi) syn. nov. = T. ledouxi Terron syn. nov. = T. lemoulti (Santschi) syn. nov. = T. mocquerysi lepida Wheeler syn. nov. = T. monardi (Santschi) syn. nov. = T. emacerata oberbecki (Forel) syn. nov. = T. emacerata odiosa (Forel) syn. nov.; and T. natalensis = T. angusta (Arnold) syn. nov. = T. capensis (F. Smith) syn. nov. = T. natalensis cuitensis (Forel) syn. nov. = T. mocquerysi lutea (Stitz) syn. nov. = T. natalensis obscurata (Emery) syn. nov. = T. prelli (Forel) syn. nov. = T. natalensis usambarensis (Forel) syn. nov. The extensive synonymy under T. mocquerysi and T. natalensis reflects the conviction that previous taxonomists underestimated the extent of intraspecific variation in these taxa, but further study and testing of this conclusion is warranted. An illustrated worker- and queen-based key is provided for all species of Tetraponera occurring in Africa and Madagascar, except the Malagasy members of the T. allaborans group. 

Abstract Using genetic, morphological, and geographical evidence, we investigate the species-level taxonomy and evolutionary history of the Pseudomyrmex elongatulus group, a clade of ants distributed from southwestern United States to Costa Rica. Through targeted enrichment of 2,524 UCE (ultraconserved element) loci we generate a phylogenomic data set and clarify the phylogenetic relationships and biogeographic history of these ants. The crown group is estimated to have originated ~8 Ma, in Mexico and/or northern Central America, and subsequently expanded into southern Central America and the southwestern Nearctic. The P. elongatulus group contains a mix of low- and high-elevation species, and there were apparently multiple transitions between these habitat types. We uncover three examples of one species—of restricted or marginal geographical distribution—being embedded phylogenetically in another species, rendering the latter paraphyletic. One of these cases involves an apparent workerless social parasite that occurs sympatrically with its parent species, with the latter serving as host. This suggests a sympatric origin of the parasite species within the distribution range of its host. Species boundaries are tested using three molecular delimitation approaches (SODA, bPTP, BPP) but these methods generate inflated species estimates (26–46 species), evidently because of a failure to distinguish population structure from species differences. In a formal taxonomic revision of the P. elongatulus group, based on almost 3,000 specimens from ~625 localities, we allow for geographic variation within species and we employ distinctness-in-sympatry criteria for testing hypotheses about species limits. Under these guidelines we recognize 13 species, of which nine are new: P. arcanus, sp. nov. (western Mexico); P. capillatus, sp. nov. (western Mexico); P. cognatus, sp. nov. (Chiapas, Mexico to Nicaragua); P. comitator, sp. nov. (Chiapas, Mexico); P. ereptor, sp. nov. (Veracruz, Mexico); P. exoratus, sp. nov. (southeastern Mexico, Honduras); P. fasciatus, sp. nov. (Chiapas, Mexico to Costa Rica); P. nimbus, sp. nov. (Costa Rica); and P. veracruzensis, sp. nov. (Veracruz, Mexico). Our study highlights the value of combining phylogenomic, phenotypic, and geographical data to resolve taxonomic and evolutionary questions.