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Systematic Entomology

Wiley

Preprints posted in the last 90 days, ranked by how well they match Systematic Entomology's content profile, based on 14 papers previously published here. The average preprint has a 0.01% match score for this journal, so anything above that is already an above-average fit.

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Phylogenomics resolves a 200-year-old puzzle: a revised tribal classification of Afro-Eurasian dung beetles (Coleoptera: Scarabaeinae)

Montanaro, G.; Lopes, F.; Gunter, N. L.; Scholtz, C.; Davis, A. L.; Losacco, F.; Rossini, M.; Gillett, C. P. D. T.; Saxton, N. A.; Stone, R. L.; Daniel, G. M.; Tarasov, S.

2026-07-23 zoology 10.64898/2026.07.22.740134 medRxiv
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BackgroundThe tribal classification of scarab dung beetles (Coleoptera: Scarabaeinae) is currently largely incomplete due to the lack of robust phylogenetic evidence supporting the assignment of many Afro-Eurasian and American genera to tribes. MethodsWe used ultraconserved elements (UCEs) to infer phylogenetic relationships across most Afro-Eurasian dung beetle lineages, including 25 of the 27 extant genera currently incertae sedis. ResultsWe recovered full support for the monophyly of previously recognised tribes and for several phylogenetically and morphologically clearly delimited new tribal-level clades, allowing us to propose a complete tribal classification for all Afro-Eurasian dung beetle genera. Thirteen new tribes are described and diagnosed: Aphengoecini trib. nov., Bohepilissini trib. nov., Catharsiini trib. nov., Chalconotini trib. nov., Circelliini trib. nov., Dwesasilvasedini trib. nov., Haroldiini trib. nov., Heliocoprini trib. nov., Janssensantini trib. nov., Macroderini trib. nov., Nesovinsoniini trib. nov., Pycnopanelini trib. nov. and Tanzanolini trib. nov. The tribe Coprini sensu novo is redefined as comprising three subtribes: Coprina, Onychothecina subtrib. nov. and Pedariina subtrib. nov. The tribe Odontolomini is downranked to a subtribe of Endroedyolini sensu novo, becoming Endroedyolini Odontolomina stat. nov. The tribe Onthophagini sensu novo is redefined and divided into three subtribes: Helictopleurina stat. nov., Oniticellina stat. nov. and Onthophagina; the remaining former subtribes of Oniticellini (Attavicinina, Drepanocerina and Liatongina) are synonymised with Oniticellina; the subtribe Alloscelina of Onthophagini is synonymised with Onthophagina (syn. nov.). The tribe Panelini stat. rev. and sensu novo, comprising the single genus Panelus, is revalidated and redefined. Updated morphological diagnoses of Elassocanthonini, Gymnopleurini, Onitini and Scarabaeini are provided. The genus Phaedotrogus is synonymised with Haroldius (Haroldiini) (syn. nov.). An identification key to all Afro-Eurasian dung beetle tribes is provided. DiscussionOur results establish a robust phylogenetic framework and revised tribal classification for Afro-Eurasian Scarabaeinae dung beetles, providing a foundation for future taxonomic, comparative and macroevolutionary research.

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Integrative taxonomy reveals cryptic diversity in Chilean Trichomycterinae (Siluriformes, Trichomycteridae)

Quezada-Romegialli, C.; Arratia, G.

2026-07-27 zoology 10.64898/2026.07.26.736611 medRxiv
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Species-level delimitation within the genus Trichomycterus remains one of the main systematic challenges within the Trichomycterinae, particularly in lineages characterised by conservative external morphology, high apparent intraspecific variation, and historical diagnostic criteria based primarily on body proportions, colouration and a few meristic characters. In central Chile, Trichomycterus areolatus has traditionally been interpreted as a widely distributed and morphologically variable species, whilst T. maculatus, originally described from "Santiago du Chili", has remained subordinate to this broad conception without a modern phylogenetic reassessment. Here we reassess the specific boundaries of T. areolatus sensu lato using an integrative approach that combines complete mitogenomes, estimates of genetic divergence and comparative morphology of the cephalic laterosensory system associated with the neurocranium. Phylogenetic analyses reveal T. areolatus sensu lato to be non-monophyletic and identify a deeply divergent lineage, geographically coherent and attributable to T. maculatus. This lineage differs from restricted T. areolatus by extensive mitochondrial divergence, comparable to that observed between recognised species of Trichomycterinae, and by discrete characters of the cephalic lateral line system, primarily related to the continuity of the supraorbital canal and the arrangement of the associated pores. The congruence between mitogenomic, nuclear and morphological evidence supports the revalidation of Trichomycterus maculatus Valenciennes, 1846, and calls for a more restricted geographic circumscription of T. areolatus. These results demonstrate that the diversity of Trichomycterinae in central Chile has been underestimated, modify previous interpretation of the distribution of the species involved, and highlight the value of integrating mitogenomics and neurocranial/laterosensory characters into the taxonomy of morphologically conservative siluriform lineages.

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Integrative morphology and phylogenetics of Arcellidae (Amoebozoa:Arcellinida), with redescription of Arcella leidyana and Arcella artocrea and description of Galeripora purdoni sp. nov.

Taylor, B. D. S.; Sousa, A. L.; Jones, R. E.; Seaquist, C.; Siemensma, F. J.; Taylor, E.; Tice, A. K.

2026-08-22 evolutionary biology 10.64898/2026.08.19.745684 medRxiv
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Arcellidae is a family of testate amoebae within Arcellinida (Amoebozoa), comprising three recognized genera: Arcella, Galeripora, and Antarcella. Although species in the family have been studied for nearly two centuries, many historically described taxa and major morphological groups remain unsampled at the molecular level. Here, we provide a comprehensive review of Arcellidae and generate new cytochrome c oxidase subunit I (COI) sequences for arcellid species from Canadian peatlands, focusing on tall-shelled Arcella historically classified in section Altae sensu Deflandre. COI phylogenetic analyses recover a strongly supported monophyletic clade corresponding to North American representatives of Altae, providing the first molecular corroboration of this morphologically defined group. Within this clade, we redescribe Arcella leidyana based on modern material from Eeyou Istchee (Quebec). We further describe Galeripora purdoni sp. nov. from a calcareous fen in eastern Ontario, representing a novel terrestrial lineage within the genus, and redescribe Galeripora artocrea, which we transfer to Arcella based on congruent molecular and morphological evidence. Phylogenomic analyses of Arcellidae isolates from the Protist 10,000 Genomes Project reveal an additional deep lineage basal to Arcella and Galeripora. Together, these results highlight hidden diversity and demonstrate the importance of integrative approaches for resolving arcellid systematics and refining its classification.

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Genomics and CT imaging reveal diversity in silk genes and gland morphology of webspinners

Markee, A.; Davis, L. J.; Davis, D. D.; Edgerly, J. S.; Stanley, E. L.; Ware, J. L.; Kawahara, A. Y.; Powell, A.; Hayashi, C. Y.; Baker, R. H.; Frandsen, P. B.

2026-08-11 evolutionary biology 10.64898/2026.08.07.743568 medRxiv
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Webspinners (Insecta: Embioptera) are an unusual insect order that are known for their subsocial behavior and prolific silk-production. Due to their unique foreleg silk glands, and spider-like ability to produce silk throughout their entire life cycle, webspinners are hypothesized to have evolved silk independently from other arthropod lineages. To date, there are no reference-quality genomes available for the order, preventing the study of their silk gene origination and diversification. Here, we assembled PacBio HiFi reference genomes and characterized the silk genes present in two webspinner species, Aposthonia ceylonica and Oligotoma nigra. The genomes reveal multiple full-length copies of the primary Embioptera silk gene, e-fibroin, that have undergone both ancestral and recent gene duplications within the group. For both species, all e-fibroin paralogs show the presence of complex repeat units consisting of multiple exons and introns that are remarkably homogenized across each gene. We also used CT-scanning of the internal silk glands to provide details concerning the localization of silk production in foreleg tarsi, and interspecific morphology. Article summaryThis study introduces the first high-quality genomes for webspinners, enabling new research on silk for evolutionary biologists and materials scientists alike. The authors sequenced two embiopteran species, Aposthonia ceylonica and Oligotoma nigra, to compare silk genes and gland structure using micro-computed tomography, an imaging method that shows internal anatomy in detail. They found multiple copies of the primary silk gene in both species that likely arose from multiple duplication events at different evolutionary times. These silk genes exhibit unusual gene structure with hierarchically organized repeat units that are highly homogenized within a gene. The findings show that silk genes have a complex evolutionary history in webspinners and provide a foundation for studying silk diversity within the order, and in the broader context of insect silk.

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EcoMorph: Universal morphological trait quantification from natural language prompts for ecological research

Amoah, E. I.; Bunch, Z.; Thomas, H. M.; Patch, H. M.; Grozinger, C.

2026-07-12 bioinformatics 10.64898/2026.07.10.737871 medRxiv
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0.O_LIMorphological traits such as floral area and body size are fundamental to ecological research, serving as inputs for studies of pollinator-plant interactions, habitat quality, and biodiversity monitoring. However, accurately measuring these traits from images remains challenging, particularly in complex field conditions where existing tools exhibit reduced accuracy and limited generalizability across taxa. C_LIO_LIWe present EcoMorph, a modular morphological measurement system that leverages the Segment Anything Model 3 (SAM3) to quantify traits across diverse ecological contexts. Unlike task-specific segmentation models requiring domain-specific training data, SAM3s prompt-based architecture enables segmentation of arbitrary biological structures from natural-language prompts, using the same underlying model across flowers, insects, and other targets without retraining. From the resulting segmentations, EcoMorph extracts three classes of measurement: area, linear dimensions, and object counts. C_LIO_LIWe validated EcoMorph across two ecological scales. At the intermediate scale, EcoMorph-derived floral area agreed closely with manual ImageJ measurements (R2 = 0.935, n = 74) under simple-background conditions and (R2 = 0.928, n = 58) under complex-background conditions, with valid predictions for 95% of images. At the fine scale, EcoMorph-derived insect body area was strongly correlated with hand-measured intertegular distance (r = 0.810, n = 349), capturing body-size variation across species from the small Bombus impatiens to the large Xylocopa virginica. Object counts matched manual counts almost exactly for well-separated insects in an insect box (R2 = 0.9997, n = 12). C_LIO_LIBy combining prompt-based segmentation with modular measurement, EcoMorph enables high-throughput quantification of area, size, and abundance from heterogeneous image sources without taxon-specific training. This generality supports a broad range of ecological applications, including pollinator and plant trait research, biodiversity and abundance monitoring, and allometric biomass estimation. C_LI

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Exotic catenulid flatworms (Platyhelminthes, Catenulida) and where to find them in a temperate climate - a field study in a botanic garden

Tratkiewicz, K.; Sysiak, M.; Zych, M.; Gasiorowski, L.

2026-08-07 zoology 10.64898/2026.08.06.743217 medRxiv
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Catenulids are free-living flatworms, common in eutrophic freshwaters such as ponds, ditches, or peatbogs, with most of the diversity described from tropical regions to date. Although the majority of the species have been described from warmer climates, most molecular studies have been done on specimens from temperate zones in Europe. We addressed this gap by sampling for exotic species in localities available in a temperate climate. In this study, we investigated catenulid diversity in the greenhouses at the University of Warsaw Botanic Garden and recorded two species known only from tropical areas (Stenostomum paraguayense and Suomina evelinae) and one exotic species recorded previously from a greenhouse in Poland (Stenostomum corderoi). Additionally, in the latter species, we provide evidence for environmentally induced coloration of sensory pits, which has not been reported thus far. We placed the collected species on a phylogeny using barcoding of 18S, 28S, and COI genes and retrieved paraphyly of the family Catenulidae, with S. evelinae forming a sister group to the genus Paracatenula, and hence we propose a revision of its systematic position. In total, we recorded six species, including three with a wide cosmopolitan distribution (C. turgida, S. grande and S. tuberculosum), and provided sequences for five of them, three of which had no previous molecular records (S. paraguayense, S. evelinae and S. corderoi). Thus, we confirm that greenhouses represent an important source of exotic species for taxonomic work on microscopic invertebrates.

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Biogeography and cryptic diversity of the ancient centipede genus Digitipes (Scolopendromorpha) in South and Southeast Asia

Dash, P.; Roy, P.; Joshi, J.

2026-07-30 evolutionary biology 10.64898/2026.07.28.741128 medRxiv
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Understanding the relative roles of vicariance and dispersal in shaping diversity and distribution patterns is central to historical biogeography. In this study, we investigate the historical biogeography of the ancient centipede genus Digitipes Attems, 1930 from South and Southeast Asia. First, we determined the phylogenetic position of the genus Digitipes within the Order Scolopendromorpha (n=414) by assembling primary and published sequences (n=30) for two mtDNA markers (COI, 16S) and one nuclear marker (28S) using Maximum Likelihood and Bayesian inference. We further used single-locus and multi-locus coalescent-based species delimitation methods to identify putative species within the genus Digitipes. We then used three fossil calibrations to estimate divergence times in a Bayesian framework, and used the resulting time-calibrated phylogeny for biogeographic analysis in a likelihood framework (BioGeoBEARS). The genus Digitipes was monophyletic with strong support, with SEA lineages nested within the Indian clade and sister to the D. barnabasi species complex from the Western Ghats. D. pruthii, the Eastern Ghats species, was nested with the Western Ghats species clade. A single-locus mPTP-based species-delimitation method suggested the presence of 24 putative species, far exceeding the number of morphologically described species, indicating an underestimation of species diversity. Divergence time estimates suggest that Digitipes began diversifying around 126 mya (100-159 mya), affirming its Gondwanan origin. Time-stratified ancestral area reconstruction suggested that early vicariance, followed by jump dispersal and range expansion, shaped the distribution of the genus Digitipes in South and Southeast Asia. There was one dispersal event from India to Southeast Asia, following a transient land connection between them, around 50 mya, supporting the Out-of-India hypothesis. Additionally, three jump dispersal events and five range expansions explained diversification within peninsular India. Particularly, D. pruthii originated from a jump dispersal event from the Central Western Ghats to the Eastern Ghats around 37 mya. Our results highlight the importance of an integrative taxonomic framework to delineate hidden diversity and to obtain robust species hypotheses for testing biogeographic hypotheses.

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Song divergence and a gleaming white iris reveal four species in a widespread Neotropical understory bird (Clibanornis rubiginosus, Furnariidae)

Villamizar, J. C.; Cuervo, A. M.

2026-08-25 zoology 10.64898/2026.08.24.746896 medRxiv
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Polytypic species with large ranges may harbor unrecognized diversity because taxonomy ranks populations differing subtly in plumage as subspecies. The Ruddy Foliage-gleaner (Clibanornis rubiginosus) exemplifies this problem. It ranges from Mexico to Brazil, with 15 subspecies, and forms a non-monophyletic complex with two congeners, yet its songs had not been compared. We measured ten spectral and temporal variables on 104 recordings covering 14 of 15 subspecies. Bayesian linear mixed models showed three song groups: eight subspecies west of the Andes share a single-note song, whereas Amazonian and Guianan populations add a short introductory note and sing longer, lower-pitched songs. Within this group, watkinsorum sings the lowest-pitched and longest song and is phylogenetically closer to C. cinnamomeigula than to its Amazonian neighbors. The third group is C. cinnamomeigula alone, a white-eyed taxon in an otherwise dark-eyed group. Its high-pitched, vibrato song resembles none other in the genus. One-note and two-note songs differ in kind without intermediates, and every two-note taxon sequenced to date falls in one clade, so C. rubiginosus is paraphyletic. We recognize four species, C. rubiginosus sensu stricto, C. cinnamomeigula, C. watkinsorum, and C. obscurus. This raises Clibanornis from five species to eight and divides its only polytypic species.

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Morphogenomic description of Cranifera cranifera (Chitwood, 1932) Kloss, 1960 from captive Blaptica dubia Serville, 1838 cockroach

Morffe, J.; Guiglielmoni, N.; Wassey, N.; Gueddach, K.; Schuster, A.; Becker, K.; Schiffer, P.; Holovachov, O.

2026-07-20 zoology 10.64898/2026.07.17.739199 medRxiv
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Nematodes of the superfamily Thelastomatoidea are found in the digestive system of various arthropods, feeding on their host microbiome. They are sometimes considered to be ecologically intermediate forms between free-living rhabditids and parasitic Spirurina, while phylogenetically they are nested within the latter. In addition to new morphological data on the male morphology, this manuscript presents the first nuclear genome assembly of a thelastomatid species, Cranifera cranifera, using long-read sequencing approach, making a total of three nuclear genomes available for superfamilyThelastomatoidea. The C. cranifera nuclear genome assembly presented here is 246 Mb long, consists of 7563 contigs, has an N50 of 43 kb and includes 94% of the BUSCO nematoda_odb12 genes. The mitochondrial genome is 24646 bases long, includes a complete set of protein coding, rRNA and tRNA genes, and a repetitive region 9731 bases long, which includes multiple copies of tRNA-Asn(gtt) and tRNA-Lys(ttt). The nuclear assembly also contained two sequence variants of the 28S rRNA gene, highlighting the presence of intragenomic variation within rRNA operon. The newly generated assemblies (nuclear and organelle) will add to a growing body of genomic resources for underrepresented and understudied animal parasitic nematodes from the Clade 3, enabling comprehensive studies in their phylogeny and trait evolution in the future.

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PhyloRBT: A Phylogenetic Approach to Detect Reference Bias in Phylogenomic Datasets

Ivan, J.; Lanfear, R.

2026-07-26 bioinformatics 10.64898/2026.07.24.740642 medRxiv
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Recent technological advancements have enabled the rapid generation of high-quality genomes across the tree of life, often resulting in multiple reference genomes for clades of phylogenetic interest. These reference genomes are often used to reconstruct phylogenetically informative loci from short-read data of newly-sequenced species. However, this approach can introduce reference bias where the reconstructed loci have erroneous similarities to those of the reference genome. Since reference bias can seriously affect downstream analyses, it is important to assess its presence in phylogenomic datasets. In this study, we propose PhyloRBT (phylogenetic reference bias test) to detect reference bias by reconstructing each locus multiple times using different reference genomes and then measuring the phylogenetic correlation between these reconstructions and the corresponding locus from the reference genomes. We applied PhyloRBT to hundreds of BUSCO loci reconstructed from short-read data of nine Eucalyptus species using 34 different reference genomes. Across the nine species, we found that more than a quarter of the reconstructed loci had significant evidence of reference bias. Excluding putatively biased loci from species tree inference resulted in a species tree topology that is more consistent with expectations from previous studies. In conclusion, PhyloRBT offers a straightforward way to detect reference bias in individual loci, and to selectively remove those biased loci from downstream analyses.

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Exploring the only known case of sympatry in sportive lemurs: isolation by distance or speciation?

Salmona, J.; RANJAVAO, B.; RASOLONDRAIBE, E.; RAKOTONANAHARY, A. N.; RALANTOHARIJAONA, T.; Jan, F.; Le Pors, B.; TEIXEIRA, H.; KUN-RODRIGUES, C.; IBOUROI, M. T.; DURHAM, S. A. O.; ZARANAINA, R.; GABILLAUD, V.; BARNAVON, M.; BECK, A.; MONTEIRO, A. R.; SOUSA, A. P.; ALEIXO-PAIS, I.; HOHENLOHE, P.; CARRIERE, S. M.; RAKOTONDRAOMPIANA, S.; RADANIELINA, T.; WOHLHAUSER, S.; RANIRISON, P.; ANDRIAHOLINIRINA, N. V.; RAKOTONDRAVONY, R.; RASOLOHARIJAONA, S.; HELLER, R.; ZAONARIVELO, J. R.; Sgarlata, G. M.; CHIKHI, L.

2026-08-28 evolutionary biology 10.64898/2026.08.27.747501 medRxiv
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Among Madagascar primates, the sportive lemurs (family Lepilemuridae) have seen their species diversity increase from eight in 2005 to 26 in 2009 mostly by applying the phylogenetic species concept to DNA barcode data. Despite the genus being speciose, only one case of sympatry is known from northern Madagascar, where two sportive lemur species described based on low mtDNA divergence, Lepilemur ankaranensis and Lepilemur milanoii, were found to co-occur at the center of their joint distribution range. Here, to clarify the taxonomy of these two species and examine their sympatry, we apply an integrative taxonomic framework to genomic and morphological data from 84 individuals of L. ankaranensis and L. milanoii, encompassing their entire distribution range and the forest of Analafiana, beyond their southernmost limit. Using clustering, multivariate, and isolation by distance analyses, we find no evidence of a sympatric zone and show that despite clear genetic differentiation between regions, the genomic and morphological diversity of the L. ankaranensis, L. milanoii-Analafiana group is clinal and explained by geographic distance. These results clarify that L. milanoii is a junior synonym of L. ankaranensis and that the Analafiana forest population belongs to L. ankaranensis, extending its distribution. It further implies that the 'sympatric' zone, the Andrafiamena forest, hosts conspecific individuals with slightly differentiated mtDNA backgrounds, rather than slightly differentiated sympatric species. Lastly, we re-evaluate the IUCN conservation metrics of L. ankaranensis, which continue to qualify as Endangered (EN) under the B1ab(i-v) criteria.

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PyiTOL: reproducible Python workflows for iTOL annotation and taxonomic monophyly assessment

Zeng, Z.; Wang, Y.

2026-08-29 bioinformatics 10.64898/2026.08.27.747471 medRxiv
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Motivation: The Interactive Tree of Life (iTOL) is widely used to display and annotate phylogenetic trees, but managing its format-sensitive annotation files impede reproducible high-throughput analyses. Among the maintained Python packages and versions evaluated, none combined template generation, taxonomic monophyly assessment and iTOL batch operations. Results: PyiTOL validates inputs, generates 31 iTOL template schemas (22 accepted by the live batch uploader), performs LCA-based monophyly classification with nested-monophyly detection, sampling-completeness states and polyphyletic subgroup decomposition, plus API upload and session replay. On a topology-constructed benchmark, all calls matched prespecified labels for 4,389 groups; on a 700-genome tree, binary mono/non-mono calls agreed with ETE4 for 409 genera; 17,294 GTDB R232 genera were processed in about 17 s. Availability and Implementation: PyiTOL 1.0.3 (Python [≥]3.10; Linux, macOS and Windows) is MIT-licensed at https://github.com/ZengZichao/PyiTOL and archived with test data at Zenodo (https://doi.org/10.5281/zenodo.22106806).

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Global vascular plants reveal persistent gaps across taxa and ecoregions

Maciel, E. A.

2026-08-28 evolutionary biology 10.64898/2026.08.24.746674 medRxiv
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Biodiversity aggregators such as GBIF provide unprecedented access to global biodiversity data, yet their representativeness remains uneven across space and taxa. This study examined the spatial and taxonomic structure of global vascular plant data available on GBIF. Six filters were applied to the GBIF vascular plant dataset, resulting in the removal of 54% of all records. Together, the filters explained more than 90% of the identified spatial issues, with duplicate and missing coordinates accounting for most of the variation. A higher number of occurrence records was associated with a greater number of spatial issues. Record distributions became progressively more even at finer taxonomic levels, from orders to species. The time series of occurrences for species, genera, and families increased sharply after 1800 and continued to rise, with no apparent stabilisation. Of the 824 ecoregions covered, 73 accounted for 72% of all occurrence records. These ecoregions spanned all continents but were strongly concentrated in Europe, followed by North America and Oceania. The analyses reveal four key patterns: (1) data volume is positively associated with spatial issues; (2) a small number of taxa account for a large proportion of records, whereas many are represented by relatively few; (3) occurrence data aggregated by GBIF have increased continuously since 1800; and (4) record coverage remains highly uneven across the world's ecoregions. These results highlight the substantial contribution of biodiversity data aggregators to expanding access to biological information while demonstrating the persistent spatial and taxonomic biases that shape their contents. Such biases should be explicitly considered when assessing data completeness and quality and when using aggregated occurrence records to infer global biodiversity patterns.

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UVfinder: a tool to extract bryophyte sex-linked gene copies from the GoFlag408 probe set

Kim, S.; Bowman, J.; Braun, E. L.; McDaniel, S.

2026-07-07 bioinformatics 10.64898/2026.07.01.735932 medRxiv
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Target enrichment sequencing using probe sets like GoFlag 408 has revolutionized phylogenetics, yet recent genomic data indicate that some probes may be sex-linked, potentially introducing topological conflict while also allowing studies of sex-specific evolutionary processes. To test for sex-linkage across the bryophytes, we developed UVfinder, a pipeline designed to identify sex-linked GoFlag loci across published moss genomes and enable sex-aware downstream analyses. Applying UVfinder to 50 dioicous moss genomes, we identified 93 probes that exhibit sex-linkage in one or more lineages, providing genomic evidence for neo-sex chromosome formation via autosome-sex chromosome fusion and gene translocation. Furthermore, by comparing species trees derived from sex-linked versus autosomal loci in Hypnales and Dicranidae, we demonstrate that sex-linked loci harbor phylogenetic information that is distinct from that in autosomes. We also discovered a pervasive female sampling bias in the genomic data, perhaps reflecting a preference among collectors for plants with sporophytes. Ultimately, our findings highlight the dynamism in sex linkage across bryophytes and suggest that sex-aware phylogenomics can be used to reconstruct ancestral karyotypes and potentially resolve topological conflict. We expect that UVfinder will facilitate the further study of sex-specific evolutionary processes, particularly with improved genome assemblies and increased sampling in males.

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Pretrained deep-learning ITS classifiers read the flanking regions, not the ITS2 barcode, and so fail on the amplicon that environmental fungal surveys sequence

O'Brien, A.; Parada, P.

2026-08-04 bioinformatics 10.64898/2026.07.29.741510 medRxiv
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Deep-learning classifiers for the fungal internal transcribed spacer (ITS) report accuracies above 90% and are increasingly proposed for environmental metabarcoding. We benchmark two pretrained models, a convolutional network and a transformer sharing a training corpus of 5.23M sequences, against two established k-mer methods on 5,222 identical queries, one per genus, evaluated on both full-length ITS and the ITS2 subregion that dominates environmental sequencing. The design favours the classifiers: queries are drawn from the same public dataset they were trained on and stratified by whether a querys genus lies in their own label space, recovered from the distributed models, while the reference the k-mer methods consult mirrors that label space and excludes the queries themselves. Even so, on full-length ITS both classifiers are outperformed by both classical methods at every rank and in both strata: SINTAX recovers the correct family for 92.0% of seen-genus and 70.3% of novel-genus queries and best-hit alignment against a 56,327-sequence reference for 92.3% and 67.2%, against 77.9% and 57.7% for the transformer and 76.5% and 54.3% for the convolutional network. A hierarchical logistic regression on k-mer counts, fitted in ten minutes to 1.07% of the MycoAI training corpus, also exceeds both and places novel genera better than either search method, and refitted on ITS2 it recovers 89.2% of seen-genus families on that amplicon against 88.6% for best-hit alignment, so neither learned classification nor the amplicon is what fails. Restricting the identical records to ITS2 costs the k-mer methods 3.5 and 3.7 percentage points of seen-genus family accuracy but costs the classifiers 49.6 and 58.0, reducing them to 28.3% and 18.5%. An ablation identifies the cause. Grafting each querys unaltered ITS2 between the flanking regions of a donor record from a different phylum returns the donors family for 34.4% of queries against the querys own for 4.2% in the convolutional model, and 63.7% against 0.8% in the transformer, from a baseline of 0.1% where no donor sequence is present. The models therefore read taxonomy principally from the flanking regions rather than from the ITS2 barcode, which explains the collapse and predicts the same failure for any subregion amplicon. Compounding this, on ITS2 the classifiers output probability all but ceases to separate novel from known genera (AUROC 0.541 and 0.503, the latter at chance, against 0.866 for alignment identity and 0.785 for the SINTAX bootstrap), so the failure is not detectable from the models own output. We recommend that reported accuracies for such models specify the amplicon region of the evaluation, state the length distribution of the training corpus, and include a same-query classical baseline.

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DICAROS: Diffeomorphic Ancestral Shape Reconstruction on Phylogenies

Severinsen, M. L.; Li, J. K.; Lim, W.; Raskin, L. Y.; Yang, G.; Sommer, S.; Hipsley, C. A.; Nielsen, R.

2026-08-22 evolutionary biology 10.64898/2026.08.21.746152 medRxiv
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Reconstructing ancestral morphologies on a phylogenetic tree is a central task in evolutionary morphometrics. Established reconstruction methods, including multivariate Brownian-motion approaches, rely on linear assumptions and do not directly model the correlations between landmarks within a shape, which can oversimplify the reconstructed morphology. The DICAROS method (Diffeomorphic Independent Contrasts for Ancestral Reconstruction of Shapes; Severinsen et al., 2026) instead fuses sibling shapes along branches with large-deformation diffeomorphic (LDDMM) landmark dynamics that model these correlations, so that ancestors remain on the shape manifold. DICAROS was shown to outperform ordinary least-squares, Brownian-motion, and penalized-likelihood reconstruction, particularly on non-symmetric trees. The dicaros package repackages that pipeline as a documented, pip-installable tool that runs on arbitrary landmark datasets from a single command. It handles 2D and 3D landmarks, Newick and NEXUS trees, a choice of Euclidean or Frechet species means, optional anchor-based alignment, and tips backed by a single specimen, and it returns the reconstructed shapes for all nodes together with the tree relabelled at its internal nodes. We demonstrate dicaros on two new datasets: a 2D leaf dataset (217 species) and a 3D guenon skull dataset (22 species).

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Evolutionary diversification of the biological screw joint in weevils

Hein, J.; Katzke, J.; Riedel, A.; Bell, O.; Casadei-Ferreira, A.; Cecilia, A.; Ershov, A.; Farago, T.; Hamann, E.; Sarkar, C.; Syrota, S.; Tavakoli, C.; Zagainov, N.; Zuber, M.; Baumbach, T.; Heethoff, M.; van de Kamp, T.

2026-08-21 zoology 10.64898/2026.08.21.746137 medRxiv
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Complex biomechanical innovations are often treated as discrete evolutionary breakthroughs, yet their diversification within large radiations remains poorly understood. Beetle leg joints provide a striking example: some weevils possess screw-like coxa-trochanteral articulations in which rotation and axial displacement are mechanically coupled, resembling engineered screw-and-nut mechanisms. Whether these joints represent isolated mechanical extremes, discrete adaptive types or part of a broader continuum of phenotypic variation has remained unknown. Here we combine synchrotron X-ray microtomography, landmark-free atlas-based morphometrics, quantitative functional morphology and phylogenetic comparative analyses to examine the mesocoxa-trochanteral joint in 68 specimens representing seven sampled family-level groups across early-diverging and derived weevil lineages. We show that screw joint evolution combines continuous variation in trochanteral shape with a restricted set of mechanically plausible joint-character combinations, rather than forming sharply separated morphological classes. True screw-and-nut joints are not confined to a distinct region of morphospace, indicating that overall form and mechanical configuration are not necessarily coupled. The occurrence of this configuration in the early diverging Caridae shows that it is not restricted to more derived families. Three-dimensional helix fitting revealed a mosaic geometry, with winding angle showing the clearest relationship with overall shape and joint architecture, whereas axial pitch varied largely independently of shape, size and lineage. Together, these patterns show that screw joint components diversified with different degrees of evolutionary integration. These results recast the weevil screw joint from a singular biomechanical curiosity into a diversified evolutionary system. They suggest that complex functional structures can evolve through the gradual recombination and differential persistence of structurally constrained and evolutionary flexible components, rather than through a single shift from simple to fully specialized designs.

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Plastome phylogenomics of the tribe Spermacoceae (Rubiaceae): taxonomic implications and a key to the genera

Nunez Florentin, M.; Claypool, K.; Huda, N.; Green, K.; Monzel, G.; Schafran, P. W.; Neupane, S.

2026-07-13 plant biology 10.64898/2026.07.10.737747 medRxiv
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The tribe Spermacoceae (Rubiaceae) comprises a morphologically diverse assemblage of approximately 1,400 species distributed across the Neotropics, Africa, Asia, Australia, and Pacific region. It remains one of the most taxonomically intractable groups in the family, with generic limits repeatedly redefined for more than two centuries. Previous phylogenetic studies based on a limited number of plastid and nuclear markers left numerous relationships unresolved and provided sparse representation of Neotropical lineages. Here, we present the first phylogenomic study of the tribe based on plastome-scale data and expanded sampling of Neotropical taxa. We sampled 121 species representing 55 genera spanning all major clades and generated 123 new plastomes, including 25 species incorporated into a molecular phylogenetic framework for the first time. Maximum-likelihood and Bayesian analyses recovered a highly resolved and strongly supported phylogeny, with uncertainty restricted to a small number of deep backbone nodes. Pollen and seed micromorphology provided additional evidence for evaluating phylogenetic relationships. The resulting phylogenetic framework clarifies generic boundaries across several problematic lineages and supports multiple taxonomic changes. Pervasive homoplasy in seed and floral characters rendered several traditionally recognized genera non-monophyletic, warranting new combinations, including Edrastima oxycoccoides, Stenotis alexanderae, and S. prostrata, and a reassessment of taxa such as Terrellianthus serpyllaceus and Oldenlandia dusenii. We further identify genera requiring additional study and provide an updated key to the 82 recognized genera of Spermacoceae. Together, these results provide the most robust phylogenetic framework yet available for the tribe and establish a foundation for future systematic, biogeographic, and evolutionary research.

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Rclade: automated taxonomic collapsing and geological-timescale annotation of time-calibrated phylogenetic trees in R

Zeng, Z.; Wang, Y.

2026-09-01 bioinformatics 10.64898/2026.08.27.747462 medRxiv
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Background: Reproducible taxonomic collapsing and geological-timescale annotation of time-calibrated phylogenetic trees in R often require coordination among several packages and repeated code for label parsing, clade validation, plotting, and export. Workflow-managed analyses additionally benefit from non-interactive configuration, predictable diagnostics, and machine-readable exit status. Results: We present Rclade, an R package that consolidates the multi-package coordination required for taxonomic collapsing into a streamlined, single-function interface. Rclade provides (1) custom ggproto objects (GeomPolygonStraight/GeomSegmentStraight) that bypass coord_munch() interpolation to achieve straight-edge rendering of collapsed triangles in circular layouts; (2) automatic detection and parsing of four taxonomic-label formats (GTDB, Silva, NCBI, embedded) plus user-supplied custom regex, with explicit input-validation contracts and parsing-accuracy evaluation on real and derived test sets; and (3) workflow embeddability through YAML configuration, library-mode APIs, and standard Unix exit codes. Benchmarks on synthetic and real datasets (200-10,000 synthetic tips and real reference trees up to 10,122 tips; 5 replicates at every scale under a unified fully rendered measurement protocol) show that the full-pipeline overhead is modest for interactive use (median {approx}0.87 s in-session rendering and {approx}8.4 s process-level wall-clock at 10,000 tips). Conclusions: Rclade is a convenience layer over the ggtree/deeptime ecosystem that reduces boilerplate while adding targeted technical improvements for circular-layout rendering and format heterogeneity management.

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Griphus Software for Multi Panel Figure Composition and Experimentation with Emphasis on Taxonomy

Aguiar, A. P.

2026-07-11 zoology 10.64898/2026.07.07.736512 medRxiv
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The preparation of multi panel figures remains a labor intensive step in scientific publication. Albeit there are specific tools available to solve this problem, they are often highly specialized, difficult to install, or time consuming to learn. Griphus is a standalone graphical application designed for rapid composition and experimentation with multi panel figures, developed by and for zoological taxonomists. Functions specifically designed for multi panel composition include automatic figure numbering and placement, aspect ratio operations, spacers, layout rotation, layout suggestions, and automatic generation of figure legends, including scale bar descriptions. The software can perform both spatial interpretation of images on the canvas and work with a simple, editable layout formula. It also enables instant multi panel composition, with numbered images and automatic contrast selection for the numbers, obtained simply by loading images. User defined parameters such as target printable dimensions, resolution, spacing, and color mode are preserved throughout the work. The program produces coordinated outputs consisting of the final composite figure, a readable file describing the layout structure, and a .gri file storing images, transformations, and parameters for exact regeneration. Griphus is intended as a complementary tool to professional image software, providing a simple and efficient environment for constructing high quality multi panel figures.