A comprehensive phylogeny and revised taxonomy illuminate the origin and diversification of the global radiation of Papilio (Lepidoptera: Papilionidae)

A cryptic new species of tiger swallowtail (Lepidoptera, Papilionidae) from eastern North America

In the eastern Great Lakes region of North America, two tiger swallowtail species have previously been recognized, Papilioglaucus Linnaeus, 1758 and Papiliocanadensis Rothschild & Jordan, 1906. A third entity, the Midsummer Tiger Swallowtail, has been treated as a P.glaucus×canadensis hybrid, and exhibits a mosaic of both intermediate and unique morphological and biological traits. Here we demonstrate that rather than being a localized, historically recent hybrid phenomenon, the Midsummer Tiger Swallowtail maintains its morphological and physiological distinctness over a large geographic region in the absence of one or both putative parental species, and was first documented in the literature nearly 150 years ago. Papiliosolstitius sp. nov. is physiologically unique in delaying post-diapause development, which results in allochronic isolation between the spring flights of P.glaucus and P.canadensis, and the late summer flight of P.glaucus. Similarly, the geographic range of Papiliosolstitius spans the region between the northern terminus of P.glaucus and southern limits of P.canadensis, remaining distinct in areas of sympatry. Defining the taxonomic identity of this unique evolutionary lineage provides an important baseline for further inquiry into what has served as an exemplary species group in evolutionary study.

Discovery of Papilio bianor Cramer, 1777 (Lepidoptera: Papilionidae) in the Central Ryukyus, Japan: inference of the dispersal pathway based on morphological and genetic analyses

More than 120 species of migrated butterflies have been recorded in the Ryukyu Islands, Japan. Biogeographically, it is important to investigate the origins and characteristics of these species as they might establish populations after accidental migration. In August 2016, a Papilio (Achillides) butterfly was collected on Sesoko Island, approximately 600 m from Okinawa Main Island. Although Papilio (Achillides) ryukyuensis Fujioka is native to this area, the individual had different wing markings from this species. To identify the butterfly and infer its origin, both morphological and genetic analyses were conducted. Morphological analysis indicated that the identification was either Papilio bianor thrasymedes Fruhstorfer from Taiwan or Papilio bianor bianor Cramer from Mainland China. Subsequently, genetic analyses confirmed that the individual should be assigned as P. b. thrasymedes. This suggests that it was migrated from Taiwan, possibly influenced by Typhoon No. 10 of 2016.

Two new taxa of brush-footed butterflies (Lepidoptera: Nymphalidae) from the Western Ghats biodiversity hotspot, southern India

A new species, Amathusia travancorica sp. nov. (Nymphalidae: Satyrinae: Amathusiini), and a new subspecies, Athyma inara sahyadriensis ssp. nov. (Nymphalidae: Limenitidinae: Limenitidini), are described from the Western Ghats biodiversity hotspot, India, based on multiple male and female specimens. The new taxa are compared with type specimens of related species and subspecies, revealing consistent differences that distinguish the new taxa. Genitalia dissections are also provided as comparative materials. Additional information is provided on historical records, distributional ranges, habits and habitat, phenology, larval host plants, and early stages. Finally, the type locality and synonymy of Pantoporia mera Swinhoe, 1917 are discussed based on comparison of type specimens (Pantoporia mera Swinhoe, 1917 syn. nov.=Athyma inara Westwood, 1850).

Bayesian tip-dated timeline for diversification and major biogeographic events in Muroidea (Rodentia), the largest mammalian radiation

BACKGROUND

Extinct organisms provide vital information about the time of origination and biogeography of extant groups. The development of phylogenetic methods to study evolutionary processes through time has revolutionized the field of evolutionary biology and led to an unprecedented expansion of our knowledge of the tree of life. Recent developments applying Bayesian approaches, using fossil taxa as tips to be included alongside their living relatives, have revitalized the use of morphological data in evolutionary tree inferences. Eumuroida rodents represent the largest group of mammals including more than a quarter of all extant mammals and have a rich fossil record spanning the last ~ 45 million years. Despite this wealth of data, our current understanding of the classification, major biogeographic patterns, and divergence times for this group comes from molecular phylogenies that use fossils only as a source of node calibrations. However, node calibrations impose several constraints on tree topology and must necessarily make a priori assumptions about the placement of fossil taxa without testing their placement in the tree.

RESULTS

We present the first morphological dataset with extensive fossil sampling for Muroidea. By applying Bayesian morphological clocks with tip dating and process-based biogeographic models, we provide a novel hypothesis for muroid relationships and revised divergence times for the clade that incorporates uncertainty in the placement of all fossil species. Even under strong violation of the clock model, we found strong congruence between results for divergence times, providing a robust timeline for muroid diversification. This new timeline was used for biogeographic analyses, which revealed a dynamic scenario mostly explained by dispersal events between and within the Palearctic and North African regions.

CONCLUSIONS

Our results provide important insights into the evolution of Muroidea rodents and clarify the evolutionary pathways of their main lineages. We exploited the advantage of tip dating Bayesian approaches in morphology-based datasets and provided a classification of the largest superfamily of mammals resulting from robust phylogenetic inference, inferring the biogeographical history, diversification, and divergence times of its major lineages.

Wiped out by an earthquake? The 'extinct' Taiwanese swallowtail butterfly (Lepidoptera, Papilionidae) was morphologically and genetically distinct

For the first time, we obtained for the first time a COI DNA barcode from museum specimens of the Old World swallowtail butterfly endemic to Taiwan, Papilio machaon ssp. sylvina, that has disappeared since the devastating Jiji earthquake in 1999 that shook Central Taiwan. We demonstrate that this population was not only phenotypically distinct, but also had a unique mitochondrial haplotype among all other Holarctic populations of P. machaon. The life history of P. m. sylvina from rearing experiments carried out in the 1990s is illustrated and discussed.

Genomic evolution and patterns of horizontal gene transfer in Papilio

The Papilio genus, known for its ecological and phenotypic diversity, is a valuable model for evolutionary studies. This study conducted a comparative genomic analysis of 11 Papilio species, revealing species-specific gene family expansions, including the UDP-glucosyltransferase 2 gene associated with insect detoxification, particularly expanding in Papilio polyxenes. Our analysis also revealed 199 horizontal gene transfer (HGT) acquired genes from 76 microbial species, with Pseudomonadota and Bacillota as common HGT donors across these genomes. Furthermore, we examined the evolutionary patterns of nine ABC transporter subfamilies, uncovering potential links between gene family evolution and environmental adaptation. This study provides new insights into evolutionary relationships and genomic adaptations within the Papilio genus, contributing to broader butterfly evolutionary research.

Identification and in vivo functional analysis of furanocoumarin-responsive cytochrome P450s in a Rutaceae-feeding Papilio butterfly

The Order Lepidoptera contains nearly 160,000 described species and most of them are specialist herbivores that use restricted plant species as hosts. Speciation that originated from host shift is one of the important factors for the diversification of Lepidoptera. Because plants prepare secondary metabolites for defense against herbivores, with varying profiles of the components among different plant taxa, the specialist herbivores need to be adapted to the toxic substances unique to their host plants. Swallowtail butterflies of the genus Papilio consist of over 200 species. Approximately 80% of them utilize Rutaceae plants, and among the remaining species, a specific subgroup uses phylogenetically distant Apiaceae plants as larval hosts. Rutaceae and Apiaceae commonly contain toxic secondary metabolites, furanocoumarins, and molecular phylogenetic studies support the concept that Apiaceae feeders were derived from Rutaceae feeders. Molecular mechanisms underlying furanocoumarin tolerance in Papilio butterflies have been investigated almost exclusively in an Apiaceae feeder by an in vitro assay. In contrast, there is little information regarding the Rutaceae feeders. Here, we focused on a Rutaceae feeder, Papilio xuthus, and identified two furanocoumarin-responsive cytochrome P450-6B (CYP6B) genes, of which one was an ortholog of a furanocoumarin-metabolizing enzyme identified in the Apiaceae-feeding Papilio while the other was previously unreported. We further conducted in vivo functional analysis using the CRISPR/Cas9 system, revealing a contribution of these CYP6Bs to furanocoumarin tolerance of P. xuthus larvae. Our findings suggest that co-option of furanocoumarin-metabolizing CYP6B enzymes at least partially contributed to the host shift from Rutaceae to Apiaceae in Papilio butterflies.

Toward transparent taxonomy: an interactive web-tool for evaluating competing taxonomic arrangements

Informative and consistent taxonomy above the species level is essential to communication about evolution, biodiversity and conservation, and yet the practice of taxonomy is considered opaque and subjective by non-taxonomist scientists and the public alike. While various proposals have tried to make the basis for the ranking and inclusiveness of taxa more transparent and objective, widespread adoption of these ideas has lagged. Here, we present TaxonomR, an interactive online decision-support tool to evaluate alternative taxonomic classifications. This tool implements an approach that quantifies the criteria commonly used in taxonomic treatments and allows the user to interactively manipulate weightings for different criteria to compare scores for taxonomic groupings under those weights. We use the butterfly taxon Argynnis to demonstrate how different weightings applied to common taxonomic criteria result in fundamentally different genus-level classifications that are predominantly used in different continents and geographic regions. These differences are objectively compared and quantified using TaxonomR to evaluate the kinds of criteria that have been emphasized in earlier classifications, and the nature of the support for current alternative taxonomic arrangements. The main role of TaxonomR is to make taxonomic decisions transparent via an explicit prioritization scheme. TaxonomR is not a prescriptive application. Rather, it aims to be a tool for facilitating our understanding of alternative taxonomic classifications that can, in turn, potentially support global harmony in biodiversity assessments through evidence-based discussion and community-wide resolution of historically entrenched taxonomic tensions.

A new species of silverline butterfly, Cigaritis Donzel, 1847 (Lepidoptera: Lycaenidae), from the Western Ghats biodiversity hotspot, India

A new species, Cigaritis conjuncta sp. nov. (Lepidoptera: Lycaenidae), is described based on five male and four female specimens from Honey Valley, Kodagu District, Karnataka, which is part of the Western Ghats biodiversity hotspot, India. Cigaritis conjuncta sp. nov. is distinguished from all other congeners in India and Sri Lanka based on the following combination of diagnostic characters in the male: (a) dorsal forewing outer half, costal margin and nearly upper half of the cell black without orange markings, the remaining wing shining deep blue, (b) dorsal hindwing tornus pale orange-red with two black spots, (c) ventral forewing bands at end of discal cell conjoined, and (e) ventral hindwing subbasal and discal bands composed of spots that are not separated but conjoined to form broad bands that have irregular outlines, leaving only a narrow background colour in between. Female is similar on the ventral side, but entirely dark brown above. Male and female genitalia are dissected and figured for two paratypes of each sex, and natural history notes on the species are provided.

Checklist of Yunnan Papilionidae (Lepidoptera: Papilionoidea) with nomenclatural notes and descriptions of new subspecies

A checklist of the Papilionidae of Yunnan is presented, with nomenclatural and taxonomic changes made. In the nomenclatural section, the junior homonym Papilio bootes nigricans Rothschild, 1895 is replaced by Papilio bootes nigricauda Lamas & Cotton nom. nov., Chilasa (Cadugoides) epycides muhabbet Koak, 2005 is synonymised with Papilio epycides camilla Rousseau-Decelle, 1947 syn. nov., Graphium cloanthus nyghmat Koak & Kemal, 2000 is placed as a junior objective synonym syn. nov. of Graphium cloanthus clymenus (Leech, 1893), and Papilio astorion Westwood, 1842 is shown to have priority over Papilio varuna White, 1842, thus the valid species name is Atrophaneura astorion (Westwood, 1842) comb. nov. In the main checklist, five new subspecies are described: Parnassius cephalus haba Hu & Cotton ssp. nov., Lamproptera curius hsinningae Hu, Zhang & Cotton ssp. nov., Lamproptera curius yangtzeanus Hu & Cotton ssp. nov., Graphium macareus vadimi Cotton & Hu ssp. nov., and Papilio krishna benyongi Hu & Cotton ssp. nov. The First Reviser Principle under the ICZN Code is invoked to solve four taxonomic problems, and 18 names are synonymised with explanations, notably Papilio machaon venchuanus Moonen, 1984 syn. nov., which is synonymised with Papilio machaon schantungensis Eller, 1936. Byasa genestieri (Oberthr, 1918) stat. nov. is separated from Byasa latreillei (Donovan, 1826), and Papilio everesti Riley, 1927 stat. nov. and P. verityi Fruhstorfer, 1907 stat. nov. are separated from Papilio machaon Linnaeus, 1758 as species. Taxa that require further confirmation of their presence in Yunnan and those that do not occur in Yunnan are enumerated.

Acute and Long-Term Consequences of Co-opted doublesex on the Development of Mimetic Butterfly Color Patterns

Novel phenotypes are increasingly recognized to have evolved by co-option of conserved genes into new developmental contexts, yet the process by which co-opted genes modify existing developmental programs remains obscure. Here, we provide insight into this process by characterizing the role of co-opted doublesex in butterfly wing color pattern development. dsx is the master regulator of insect sex differentiation but has been co-opted to control the switch between discrete nonmimetic and mimetic patterns in Papilio alphenor and its relatives through the evolution of novel mimetic alleles. We found dynamic spatial and temporal expression pattern differences between mimetic and nonmimetic butterflies throughout wing development. A mimetic color pattern program is switched on by a pulse of dsx expression in early pupal development that causes acute and long-term differential gene expression, particularly in Wnt and Hedgehog signaling pathways. RNAi suggested opposing, novel roles for these pathways in mimetic pattern development. Importantly, Dsx co-option caused Engrailed, a primary target of Hedgehog signaling, to gain a novel expression domain early in pupal wing development that is propagated through mid-pupal development to specify novel mimetic patterns despite becoming decoupled from Dsx expression itself. Altogether, our findings provide multiple views into how co-opted genes can both cause and elicit changes to conserved networks and pathways to result in development of novel, adaptive phenotypes.