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. 2025 Jul 31;10:395. [Version 1] doi: 10.12688/wellcomeopenres.24656.1

The genome sequence of the Dusky Meadow Brown, Cercyonis lycaon (Lepidoptera: Nymphalidae)

Yannick Chittaro 1, Eric Toro-Delgado 2, Kay Lucek 3, Charlotte J Wright 4,a, Joana I Meier 4, Mark L Blaxter 4; Wellcome Sanger Institute Tree of Life Management, Samples and Laboratory team; Wellcome Sanger Institute Scientific Operations: Sequencing Operations; Wellcome Sanger Institute Tree of Life Core Informatics team; Tree of Life Core Informatics collective; Project Psyche Community
PMCID: PMC12411839  PMID: 40917438

Abstract

We present a genome assembly from a female specimen of Cercyonis lycaon (Dusky Meadow Brown; Arthropoda; Insecta; Lepidoptera; Nymphalidae). The assembly contains two haplotypes with total lengths of 601.00 megabases and 548.79 megabases. Most of haplotype 1 (94.99%) is scaffolded into 30 chromosomal pseudomolecules, including the W and Z sex chromosomes. Haplotype 2 was assembled to scaffold level. The mitochondrial genome has also been assembled, with a length of 15.2 kilobases.

Keywords: Cercyonis lycaon, Dusky Meadow Brown, genome sequence, chromosomal, Lepidoptera

Species taxonomy

Eukaryota; Opisthokonta; Metazoa; Eumetazoa; Bilateria; Protostomia; Ecdysozoa; Panarthropoda; Arthropoda; Mandibulata; Pancrustacea; Hexapoda; Insecta; Dicondylia; Pterygota; Neoptera; Endopterygota; Amphiesmenoptera; Lepidoptera; Glossata; Neolepidoptera; Heteroneura; Ditrysia; Obtectomera; Papilionoidea; Nymphalidae; Satyrinae; Satyrini; Maniolina; Cercyonis; Hyponephele; Cercyonis lycaon (NCBI:txid3038947)

Background

The Dusky Meadow Brown ( Cercyonis lycaon) is a species of butterfly in the family Nymphalidae, subfamily Satyrinae. Its wing dorsal side is dark brown, while the ventral side is orange with a grey margin on the forewing and grey with black marbling on the hindwing, which is also festooned ( Tolman & Lewington, 2011). This species is sexually dimorphic, with dorsal forewings presenting subapical black ocelli and androconia in males and large black ocelli framed in orange in females. It can be distinguished from the oriental meadow brown ( C. lupina) by the male’s androconia (narrower in C. lycaon) and the extent of orange colouration on the forewing dorsal side in females (more orange in C. lycaon).

Cercyonis lycaon is found from the Iberian Peninsula throughout most of Europe (except the plains of western France up to eastern Germany, the British and Irish Isles and most of Scandinavia), as well as Anatolia, the Caucasus, Iran, and southern Russia up to lake Baikal in Central Asia ( Kudrna et al., 2015; Tolman & Lewington, 2011). It is a cryo-xerophilous species inhabiting dry montane and steppic habitats between 800 and 2 000 m ( García-Barros et al., 2013). It is an univoltine species, on flight between July and September, and overwinters as 1st or 2nd instar larva ( Lafranchis et al., 2015; LSPN, 1987; Vila et al., 2018). Females lay eggs individually on the grasses of Poaceae, such as Festuca, Bromus and Stipa ( Vila et al., 2018). Males exhibit territorial behaviour. This butterfly is classified as Least Concern (LC) by the European Red List of Butterflies ( Van Swaay et al., 2010). However, it is local and scarce in some regions, such as Catalonia and Switzerland, where it is considered Vulnerable ( Vila et al., 2018; Wermeille et al., 2014).

Cytogenetic studies determined a haploid chromosome number of n = 29 based on specimens from France and Turkey ( De Lesse, 1960). Mitochondrial data (DNA barcodes) suggests a high genetic diversity and pronounced genetic structure, with some lineages in the east Mediterranean that are highly divergent from the main European one ( Dapporto et al., 2022). However, some of these lineages may correspond to other closely related taxa, as the lycaon species complex is poorly studied and suspected to contain more species in West Asia ( Lukhtanov & Novikova, 2015; Tshikolovets, 2011). The generic classification is also debated, as historically C. lycaon had been classified as Hyponephele, which some authors consider a subgenus of Cercyonis ( Zhang et al., 2020). Although we follow the NCBI taxonomy, given the reciprocal monophyly of Hyponephele and Cercyonis sensu stricto and the lack of precedent for using Cercyonis for Old World taxa, we favour the use of Hyponephele as genus to maintain taxonomic stability, at least until further evidence with a more extensive taxon sampling is gathered. The reference genome presented here will prove invaluable in clarifying the taxonomy of the genus and the diversity within the lycaon complex.

We present a chromosome-level, haplotype-resolved genome sequence of C. lycaon, sequenced as part of Project Psyche. The sequence data were derived from a female specimen ( Figure 1) collected from Conthey, Valais, Switzerland.

Figure 1. Voucher photograph of the Cercyonis lycaon (ilCerLyca1) specimen used for genome sequencing.

Figure 1.

Methods

Sample acquisition and DNA barcoding

The specimen used for genome sequencing was an adult female Cercyonis lycaon (specimen ID SAN28000143, ToLID ilCerLyca1; Figure 1), collected from Conthey, Valais, Switzerland (latitude 46.2872, longitude 7.3116; elevation 1 650 m) on 02/08/2023. The specimen was collected and identified by Yannick Chittaro (Info Fauna, Neuchâtel, Switzerland).

Nucleic acid extraction

Protocols for high molecular weight (HMW) DNA extraction developed at the Wellcome Sanger Institute (WSI) Tree of Life Core Laboratory are available on protocols.io ( Howard et al., 2025). The ilCerLyca1 sample was weighed and triaged to determine the appropriate extraction protocol. Tissue from the thorax was homogenised by powermashing using a PowerMasher II tissue disruptor.

HMW DNA was extracted in the WSI Scientific Operations core using the Automated MagAttract v2 protocol. DNA was sheared into an average fragment size of 12–20 kb following the Megaruptor®3 for LI PacBio protocol. Sheared DNA was purified by automated SPRI (solid-phase reversible immobilisation). The concentration of the sheared and purified DNA was assessed using a Nanodrop spectrophotometer and Qubit Fluorometer using the Qubit dsDNA High Sensitivity Assay kit. Fragment size distribution was evaluated by running the sample on the FemtoPulse system. For this sample, the final post-shearing DNA had a Qubit concentration of 33.03 ng/μL and a yield of 1 552.41 ng, with a fragment size of 14.4 kb. The 260/280 spectrophotometric ratio was 2.01, and the 260/230 ratio was 3.25.

PacBio HiFi library preparation and sequencing

Library preparation and sequencing were performed at the WSI Scientific Operations core. Libraries were prepared using the SMRTbell Prep Kit 3.0 (Pacific Biosciences, California, USA), following the manufacturer’s instructions. The kit includes reagents for end repair/A-tailing, adapter ligation, post-ligation SMRTbell bead clean-up, and nuclease treatment. Size selection and clean-up were performed using diluted AMPure PB beads (Pacific Biosciences). DNA concentration was quantified using a Qubit Fluorometer v4.0 (ThermoFisher Scientific) and the Qubit 1X dsDNA HS assay kit. Final library fragment size was assessed with the Agilent Femto Pulse Automated Pulsed Field CE Instrument (Agilent Technologies) using the gDNA 55 kb BAC analysis kit.

The sample was sequenced on a Revio instrument (Pacific Biosciences). The prepared library was normalised to 2 nM, and 15 μL was used for making complexes. Primers were annealed and polymerases bound to generate circularised complexes, following the manufacturer’s instructions. Complexes were purified using 1.2X SMRTbell beads, then diluted to the Revio loading concentration (200–300 pM) and spiked with a Revio sequencing internal control. The sample was sequenced on a Revio 25M SMRT cell. The SMRT Link software (Pacific Biosciences), a web-based workflow manager, was used to configure and monitor the run and to carry out primary and secondary data analysis.

Specimen details, sequencing platforms, and data yields are summarised in Table 1.

Table 1. Specimen and sequencing data for BioProject PRJEB78762.

Platform PacBio HiFi Hi-C
ToLID ilCerLyca1 ilCerLyca1
Specimen ID SAN28000143 SAN28000143
BioSample (source individual) SAMEA115117751 SAMEA115117751
BioSample (tissue) SAMEA115117754 SAMEA115117753
Tissue thorax head
Sequencing platform and model Revio Illumina NovaSeq X
Run accessions ERR13485727 ERR13493984
Read count total 2.04 million 782.12 million
Base count total 21.56 Gb 118.10 Gb

Hi-C

Sample preparation and crosslinking

The Hi-C sample was prepared from 20–50 mg of frozen head tissue of the ilCerLyca1 sample using the Arima-HiC v2 kit (Arima Genomics). Following the manufacturer’s instructions, tissue was fixed and DNA crosslinked using TC buffer to a final formaldehyde concentration of 2%. The tissue was homogenised using the Diagnocine Power Masher-II. Crosslinked DNA was digested with a restriction enzyme master mix, biotinylated, and ligated. Clean-up was performed with SPRISelect beads before library preparation. DNA concentration was measured with the Qubit Fluorometer (Thermo Fisher Scientific) and Qubit HS Assay Kit. The biotinylation percentage was estimated using the Arima-HiC v2 QC beads.

Hi-C library preparation and sequencing

Biotinylated DNA constructs were fragmented using a Covaris E220 sonicator and size selected to 400–600 bp using SPRISelect beads. DNA was enriched with Arima-HiC v2 kit Enrichment beads. End repair, A-tailing, and adapter ligation were carried out with the NEBNext Ultra II DNA Library Prep Kit (New England Biolabs), following a modified protocol where library preparation occurs while DNA remains bound to the Enrichment beads. Library amplification was performed using KAPA HiFi HotStart mix and a custom Unique Dual Index (UDI) barcode set (Integrated DNA Technologies). Depending on sample concentration and biotinylation percentage determined at the crosslinking stage, libraries were amplified with 10–16 PCR cycles. Post-PCR clean-up was performed with SPRISelect beads. Libraries were quantified using the AccuClear Ultra High Sensitivity dsDNA Standards Assay Kit (Biotium) and a FLUOstar Omega plate reader (BMG Labtech).

Prior to sequencing, libraries were normalised to 10 ng/μL. Normalised libraries were quantified again and equimolar and/or weighted 2.8 nM pools. Pool concentrations were checked using the Agilent 4200 TapeStation (Agilent) with High Sensitivity D500 reagents before sequencing. Sequencing was performed using paired-end 150 bp reads on the Illumina NovaSeq X.

Specimen details, sequencing platforms, and data yields are summarised in Table 1.

Genome assembly

Prior to assembly of the PacBio HiFi reads, a database of k-mer counts ( k = 31) was generated from the filtered reads using FastK. GenomeScope2 ( Ranallo-Benavidez et al., 2020) was used to analyse the k-mer frequency distributions, providing estimates of genome size, heterozygosity, and repeat content.

The HiFi reads were assembled using Hifiasm in Hi-C phasing mode ( Cheng et al., 2021; Cheng et al., 2022), producing two haplotypes. Hi-C reads ( Rao et al., 2014) were mapped to the primary contigs using bwa-mem2 ( Vasimuddin et al., 2019). Contigs were further scaffolded with Hi-C data in YaHS ( Zhou et al., 2023), using the --break option for handling potential misassemblies. The scaffolded assemblies were evaluated using Gfastats ( Formenti et al., 2022), BUSCO ( Manni et al., 2021) and MERQURY.FK ( Rhie et al., 2020).

The mitochondrial genome was assembled using MitoHiFi ( Uliano-Silva et al., 2023), which runs MitoFinder ( Allio et al., 2020) and uses these annotations to select the final mitochondrial contig and to ensure the general quality of the sequence.

Assembly curation

The assembly was decontaminated using the Assembly Screen for Cobionts and Contaminants ( ASCC) pipeline. TreeVal was used to generate the flat files and maps for use in curation. Manual curation was conducted primarily in PretextView and HiGlass ( Kerpedjiev et al., 2018). Scaffolds were visually inspected and corrected as described by Howe et al. (2021). Manual corrections included 7 breaks and 12 joins. The curation process is documented at https://gitlab.com/wtsi-grit/rapid-curation. PretextSnapshot was used to generate a Hi-C contact map of the final assembly.

Assembly quality assessment

Chromosomal painting was performed using lep_busco_painter using Merian elements, which represent the 32 ancestral linkage groups in Lepidoptera ( Wright et al., 2024). Painting was based on gene locations from the lepidoptera_odb10 BUSCO analysis and chromosome lengths from the genome index produced using SAMtools faidx ( Danecek et al., 2021). Each complete BUSCO (including both single-copy and duplicated BUSCOs) was assigned to a Merian element using a reference database, and coloured positions were plotted along chromosomes drawn to scale.

The Merqury.FK tool ( Rhie et al., 2020), run in a Singularity container ( Kurtzer et al., 2017), was used to evaluate k-mer completeness and assembly quality for both haplotypes using the k-mer databases ( k = 31) computed prior to genome assembly. The analysis outputs included assembly QV scores and completeness statistics.

The genome was analysed using the BlobToolKit pipeline, a Nextflow implementation of the earlier Snakemake BlobToolKit pipeline ( Challis et al., 2020). The pipeline aligns PacBio reads using minimap2 ( Li, 2018) and SAMtools ( Danecek et al., 2021) to generate coverage tracks. Simultaneously, it queries the GoaT database ( Challis et al., 2023) to identify relevant BUSCO lineages and runs BUSCO ( Manni et al., 2021). For the three domain-level BUSCO lineages, BUSCO genes are aligned to the UniProt Reference Proteomes database ( Bateman et al., 2023) using DIAMOND blastp ( Buchfink et al., 2021). The genome is divided into chunks based on the density of BUSCO genes from the closest taxonomic lineage, and each chunk is aligned to the UniProt Reference Proteomes database with DIAMOND blastx. Sequences without hits are chunked using seqtk and aligned to the NT database with blastn ( Altschul et al., 1990). The BlobToolKit suite consolidates all outputs into a blobdir for visualisation. The BlobToolKit pipeline was developed using nf-core tooling ( Ewels et al., 2020) and MultiQC ( Ewels et al., 2016), with package management via Conda and Bioconda ( Grüning et al., 2018), and containerisation through Docker ( Merkel, 2014) and Singularity ( Kurtzer et al., 2017).

Genome sequence report

Sequence data

The genome of a specimen of Cercyonis lycaon was sequenced using Pacific Biosciences single-molecule HiFi long reads, generating 21.56 Gb (gigabases) from 2.04 million reads, which were used to assemble the genome. GenomeScope2.0 analysis estimated the haploid genome size at 560.00 Mb, with a heterozygosity of 1.82% and repeat content of 42.08%. These estimates guided expectations for the assembly. Based on the estimated genome size, the sequencing data provided approximately 37× coverage. Hi-C sequencing produced 118.10 Gb from 782.12 million reads, which were used to scaffold the assembly. Table 1 summarises the specimen and sequencing details.

Assembly statistics

The genome was assembled into two haplotypes using Hi-C phasing. Haplotype 1 was curated to chromosome level, while haplotype 2 was assembled to scaffold level. The final assembly has a total length of 601.00 Mb in 209 scaffolds, with 121 gaps, and a scaffold N50 of 20.64 Mb ( Table 2).

Table 2. Genome assembly statistics.

Assembly name ilCerLyca1.hap1.1 ilCerLyca1.hap2.1
Assembly accession GCA_964270755.1 GCA_964270765.1
Assembly level chromosome scaffold
Span (Mb) 601.00 548.79
Number of chromosomes 30 N/A
Number of contigs 330 302
Contig N50 7.85 Mb 7.66 Mb
Number of scaffolds 209 189
Scaffold N50 20.64 Mb 20.16 Mb
Longest scaffold length (Mb) 26.43 N/A
Sex chromosomes W and Z N/A
Organelles Mitochondrial genome: 15.2 kb N/A

Most of the assembly sequence (94.99%) was assigned to 30 chromosomal-level scaffolds, representing 28 autosomes and the W and Z sex chromosomes. These chromosome-level scaffolds, confirmed by Hi-C data, are named according to size ( Figure 2; Table 3). Chromosome painting with Merian elements illustrates the distribution of orthologues along chromosomes and highlights patterns of chromosomal evolution relative to Lepidopteran ancestral linkage groups ( Figure 3).

Figure 2. Hi-C contact map of the Cercyonis lycaon genome assembly.

Figure 2.

Assembled chromosomes are shown in order of size and labelled along the axes.

Figure 3. Merian elements painted across chromosomes in the ilCerLyca1.hap1.1 assembly of Cercyonis lycaon.

Figure 3.

Chromosomes are drawn to scale, with the positions of orthologues shown as coloured bars. Each orthologue is coloured by the Merian element that it belongs to. All orthologues which could be assigned to Merian elements are shown.

Table 3. Chromosomal pseudomolecules in the haplotype 1 genome assembly of Cercyonis lycaon ilCerLyca1.

INSDC accession Molecule Length (Mb) GC% Assigned Merian
elements
OZ185245.1 1 24.61 37 M1
OZ185246.1 2 24.41 36.50 M2
OZ185247.1 3 24.01 37 M17;M20
OZ185248.1 4 23.99 36.50 M8
OZ185249.1 5 22.99 36.50 M19;M26
OZ185250.1 6 22.66 36.50 M3
OZ185251.1 7 22.65 36.50 M9
OZ185252.1 8 22.07 36.50 M5
OZ185253.1 9 21.91 37 M12
OZ185254.1 10 21.78 37 M14;M29
OZ185255.1 11 21.36 36.50 M18
OZ185256.1 12 20.77 36.50 M7
OZ185257.1 13 20.64 36.50 M16
OZ185258.1 14 20.33 36.50 M6
OZ185259.1 15 19.77 36.50 M21
OZ185260.1 16 19.52 37 M22
OZ185261.1 17 19.51 36.50 M4
OZ185262.1 18 19.44 37 M15
OZ185263.1 19 19.16 37 M10
OZ185264.1 20 18.52 37 M11
OZ185265.1 21 17.44 37 M23
OZ185266.1 22 17.14 36.50 M13
OZ185267.1 23 14.36 37 M24
OZ185268.1 24 13.89 38.50 M30
OZ185269.1 25 13.66 36.50 M28
OZ185270.1 26 11.76 37 M27
OZ185271.1 27 11.47 38 M31
OZ185272.1 28 11.08 37 M25
OZ185243.1 W 3.58 38 N/A
OZ185244.1 Z 26.43 37 MZ

The mitochondrial genome was also assembled. This sequence is included as a contig in the multifasta file of the genome submission and as a standalone record.

Assembly quality metrics

For haplotype 1, the estimated QV is 64.8, and for haplotype 2, 65.8. When the two haplotypes are combined, the assembly achieves an estimated QV of 65.2. The k-mer completeness is 71.32% for haplotype 1, 67.87% for haplotype 2, and 99.38% for the combined haplotypes ( Figure 4). BUSCO analysis using the lepidoptera_odb10 reference set ( n = 5 286) ( Kriventseva et al., 2019) identified 98.5% of the expected gene set (single = 97.8%, duplicated = 0.6%) for haplotype 1. The snail plot in Figure 5 summarises the scaffold length distribution and other assembly statistics for haplotype 1. The blob plot in Figure 6 shows the distribution of scaffolds by GC proportion and coverage for haplotype 1.

Figure 4. Evaluation of k-mer completeness using MerquryFK.

Figure 4.

This plot illustrates the recovery of k-mers from the original read data in the final assemblies. The horizontal axis represents k-mer multiplicity, and the vertical axis shows the number of k-mers. The black curve represents k-mers that appear in the reads but are not assembled. The green curve (the homozygous peak) corresponds to k-mers shared by both haplotypes and the red and blue curves (the heterozygous peaks) show k-mers found only in one of the haplotypes.

Figure 5. Assembly metrics for ilCerLyca1.hap1.1.

Figure 5.

The BlobToolKit snail plot provides an overview of assembly metrics and BUSCO gene completeness. The circumference represents the length of the whole genome sequence, and the main plot is divided into 1,000 bins around the circumference. The outermost blue tracks display the distribution of GC, AT, and N percentages across the bins. Scaffolds are arranged clockwise from longest to shortest and are depicted in dark grey. The longest scaffold is indicated by the red arc, and the deeper orange and pale orange arcs represent the N50 and N90 lengths. A light grey spiral at the centre shows the cumulative scaffold count on a logarithmic scale. A summary of complete, fragmented, duplicated, and missing BUSCO genes in the set is presented at the top right. An interactive version of this figure can be accessed on the BlobToolKit viewer.

Figure 6. BlobToolKit GC-coverage plot for ilCerLyca1.hap1.1.

Figure 6.

Blob plot showing sequence coverage (vertical axis) and GC content (horizontal axis). The circles represent scaffolds, with the size proportional to scaffold length and the colour representing phylum membership. The histograms along the axes display the total length of sequences distributed across different levels of coverage and GC content. An interactive version of this figure is available on the BlobToolKit viewer.

Table 4 lists the assembly metric benchmarks adapted from Rhie et al. (2021) the Earth BioGenome Project Report on Assembly Standards September 2024. The EBP metric, calculated for the haplotype 1, is 6.C.Q64, meeting the recommended reference standard.

Table 4. Earth Biogenome Project summary metrics for the Cercyonis lycaon assembly.

Measure Value Benchmark
EBP summary (haplotype 1) 6.7.Q64 6.C.Q40
Contig N50 length 7.85 Mb ≥ 1 Mb
Scaffold N50 length 20.64 Mb = chromosome N50
Consensus quality (QV) Haplotype 1: 64.8; haplotype 2: 65.8; combined: 65.2 ≥ 40
k-mer completeness Haplotype 1: 71.32%; Haplotype 2: 67.87%; combined: 99.38% ≥ 95%
BUSCO C:98.5%[S:97.8%‚D:0.6%]‚ F:0.3%‚M:1.3%‚n:5 286 S > 90%; D < 5%
Percentage of assembly assigned to chromosomes 94.99% ≥ 90%

Wellcome Sanger Institute – Legal and Governance

The materials that have contributed to this genome note have been supplied by a Tree of Life collaborator. The Wellcome Sanger Institute employs a process whereby due diligence is carried out proportionate to the nature of the materials themselves, and the circumstances under which they have been/are to be collected and provided for use. The purpose of this is to address and mitigate any potential legal and/or ethical implications of receipt and use of the materials as part of the research project, and to ensure that in doing so, we align with best practice wherever possible. The overarching areas of consideration are:

  • Ethical review of provenance and sourcing of the material

  • Legality of collection, transfer and use (national and international).

Each transfer of samples is undertaken according to a Research Collaboration Agreement or Material Transfer Agreement entered into by the Tree of Life collaborator, Genome Research Limited (operating as the Wellcome Sanger Institute), and in some circumstances, other Tree of Life collaborators.

Funding Statement

This work was supported by Wellcome through core funding to the Wellcome Sanger Institute (220540). E. T-D. is supported by an FPU grant from the Spanish Ministry of Science, Innovation and Universities (MCIU; grant number FPU22/02358). KL was supported by a grant (Grant ID 202869) from the Swiss National Science Foundation (SNSF).

The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

[version 1; peer review: 3 approved]

Data availability

European Nucleotide Archive: Cercyonis lycaon (dusky meadow brown). Accession number PRJEB78762. The genome sequence is released openly for reuse. The Cercyonis lycaon genome sequencing initiative is part of the Sanger Institute Tree of Life Programme (PRJEB43745) and Project Psyche (PRJEB71705). All raw sequence data and the assembly have been deposited in INSDC databases. The genome will be annotated using available RNA-Seq data and presented through Ensembl at the European Bioinformatics Institute. Raw data and assembly accession identifiers are reported in Table 1 and Table 2.

Pipelines used for genome assembly at the WSI Tree of Life are available at https://pipelines.tol.sanger.ac.uk/pipelines. Table 5 lists software versions used in this study.

Table 5. Software versions and sources.

Software Version Source
BEDTools 2.30.0 https://github.com/arq5x/bedtools2
BLAST 2.14.0 ftp://ftp.ncbi.nlm.nih.gov/blast/executables/blast+/
BlobToolKit 4.3.9 https://github.com/blobtoolkit/blobtoolkit
BUSCO 5.5.0 https://gitlab.com/ezlab/busco
bwa-mem2 2.2.1 https://github.com/bwa-mem2/bwa-mem2
Cooler 0.8.11 https://github.com/open2c/cooler
DIAMOND 2.1.8 https://github.com/bbuchfink/diamond
fasta_windows 0.2.4 https://github.com/tolkit/fasta_windows
FastK 1.1 https://github.com/thegenemyers/FASTK
GenomeScope2.0 2.0.1 https://github.com/tbenavi1/genomescope2.0
Gfastats 1.3.6 https://github.com/vgl-hub/gfastats
GoaT CLI 0.2.5 https://github.com/genomehubs/goat-cli
Hifiasm 0.19.8-r603 https://github.com/chhylp123/hifiasm
HiGlass 1.13.4 https://github.com/higlass/higlass
lep_busco_painter 1.0.0 https://github.com/charlottewright/lep_busco_painter
MerquryFK 1.1 https://github.com/thegenemyers/MERQURY.FK
Minimap2 2.24-r1122 https://github.com/lh3/minimap2
MitoHiFi 3 https://github.com/marcelauliano/MitoHiFi
MultiQC 1.14; 1.17 and 1.18 https://github.com/MultiQC/MultiQC
Nextflow 23.10.0 https://github.com/nextflow-io/nextflow
PretextSnapshot N/A https://github.com/sanger-tol/PretextSnapshot
PretextView 0.2.5 https://github.com/sanger-tol/PretextView
samtools 1.19.2 https://github.com/samtools/samtools
sanger-tol/ascc 0.1.0 https://github.com/sanger-tol/ascc
sanger-tol/blobtoolkit 0.6.0 https://github.com/sanger-tol/blobtoolkit
Seqtk 1.3 https://github.com/lh3/seqtk
Singularity 3.9.0 https://github.com/sylabs/singularity
TreeVal 1.2.0 https://github.com/sanger-tol/treeval
YaHS 1.2a.2 https://github.com/c-zhou/yahs

Author information

Contributors are listed at the following links:

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Wellcome Open Res. 2025 Sep 11. doi: 10.21956/wellcomeopenres.27170.r128202

Reviewer response for version 1

Arun Sethuraman 2, Jackson Wolfe 1

Summary: The authors report a high quality nuclear genome (~600Mb) of the dusky meadow brown, with 95% of the genome assembled into 30 chromosomal scaffolds, and a mitochondrial genome of 15.2 kb. 

The authors do a good job of describing the methods used in generating the assembly. The introduction section included sufficient biological information regarding the rationale for the project.

No major concerns were noted by the reviewers, all methods are accessible and reproducible, with the software and its parameters. The genome itself available and open for reuse via EBI.

Are sufficient details of methods and materials provided to allow replication by others?

Yes

Is the rationale for creating the dataset(s) clearly described?

Yes

Are the datasets clearly presented in a useable and accessible format?

Yes

Are the protocols appropriate and is the work technically sound?

Yes

Reviewer Expertise:

Genomics, population genetics, evolution

We confirm that we have read this submission and believe that we have an appropriate level of expertise to confirm that it is of an acceptable scientific standard.

Wellcome Open Res. 2025 Sep 4. doi: 10.21956/wellcomeopenres.27170.r128205

Reviewer response for version 1

Arun Arumugaperumal 1

The data note describes the genome sequence of Cercyonis lycaon, commonly known as the Dusky Meadow Brown. The photograph of the specimen remains in Figure 1 is of very good quality. This is the first report of the high quality genome of the butterfly species. The assembly reported is of size 601 Mb distributed among 30 chromosomes. The mitogenome has also been assembled of size 15.2 kb. The genomic DNA was sequenced using high-end sequencing machines. The assembly was said to be decontaminated by ASCC pipeline. What was the result? Does the presented genome size after removal of considerable amount of bases? The blob plot also shows emergence of a different blob.

The links provided in the data note pointing to databases were working fine. A BUSCO completeness of 98.5% indicates that the genome is a near-complete one. The data note can be indexed.

Are sufficient details of methods and materials provided to allow replication by others?

Yes

Is the rationale for creating the dataset(s) clearly described?

Yes

Are the datasets clearly presented in a useable and accessible format?

Yes

Are the protocols appropriate and is the work technically sound?

Yes

Reviewer Expertise:

Bioinformatics; Genomics

I confirm that I have read this submission and believe that I have an appropriate level of expertise to confirm that it is of an acceptable scientific standard.

Wellcome Open Res. 2025 Aug 30. doi: 10.21956/wellcomeopenres.27170.r128203

Reviewer response for version 1

Annabel Whibley 1,2

Chittaro and colleagues report the genome assembly of the Dusky Meadow Brown butterfly (Cercyonis lyacon).  This species was sequenced as part of Project Psyche, a multi-stakeholder project with an overarching goal to sequence all European Lepidopteran species.

The background section sets out very effectively the natural history, population distribution, taxonomic context and karyotype evidence of C. lyracon and the voucher specimen photograph is of good quality. The sample processing methods section contains hyperlinks to protocols which have been given DOIs. I assume that a new DOI would be minted when the protocol version is updated, but I wonder whether it would be helpful to also note the protocol versions in the text itself.

Combining Revio HiFi data and Arima Hi-C, the genome assembly is of exceptional quality (formally 6.C.Q64.). Close to 95% of scaffolds have been assigned to chromosomes, and BUSCO and kmer completeness are >98% and >99% respectively. formally 6.C.Q64. The use of a female individual means that both Z and W chromosomes have been captured, which adds to the utility of the reference. The inclusion of analyses of Merian elements, reconstructing ancestral linkage groups, is a really nice addition to standard elements of the DToL reporting. As usual for the data notes, the report follows templating and the methodology, reporting of sample metadata, protocols and assembly protocols are comprehensively and clearly documented.

Please note there is a typo in Table 4 (for the EBP summary of haplotype 1 Value; it should be 6.C.Q64 not 6.7.Q64).

Are sufficient details of methods and materials provided to allow replication by others?

Yes

Is the rationale for creating the dataset(s) clearly described?

Yes

Are the datasets clearly presented in a useable and accessible format?

Yes

Are the protocols appropriate and is the work technically sound?

Yes

Reviewer Expertise:

Genomics, Bioinformatics

I confirm that I have read this submission and believe that I have an appropriate level of expertise to confirm that it is of an acceptable scientific standard.

Associated Data

    This section collects any data citations, data availability statements, or supplementary materials included in this article.

    Data Availability Statement

    European Nucleotide Archive: Cercyonis lycaon (dusky meadow brown). Accession number PRJEB78762. The genome sequence is released openly for reuse. The Cercyonis lycaon genome sequencing initiative is part of the Sanger Institute Tree of Life Programme (PRJEB43745) and Project Psyche (PRJEB71705). All raw sequence data and the assembly have been deposited in INSDC databases. The genome will be annotated using available RNA-Seq data and presented through Ensembl at the European Bioinformatics Institute. Raw data and assembly accession identifiers are reported in Table 1 and Table 2.

    Pipelines used for genome assembly at the WSI Tree of Life are available at https://pipelines.tol.sanger.ac.uk/pipelines. Table 5 lists software versions used in this study.

    Table 5. Software versions and sources.

    Software Version Source
    BEDTools 2.30.0 https://github.com/arq5x/bedtools2
    BLAST 2.14.0 ftp://ftp.ncbi.nlm.nih.gov/blast/executables/blast+/
    BlobToolKit 4.3.9 https://github.com/blobtoolkit/blobtoolkit
    BUSCO 5.5.0 https://gitlab.com/ezlab/busco
    bwa-mem2 2.2.1 https://github.com/bwa-mem2/bwa-mem2
    Cooler 0.8.11 https://github.com/open2c/cooler
    DIAMOND 2.1.8 https://github.com/bbuchfink/diamond
    fasta_windows 0.2.4 https://github.com/tolkit/fasta_windows
    FastK 1.1 https://github.com/thegenemyers/FASTK
    GenomeScope2.0 2.0.1 https://github.com/tbenavi1/genomescope2.0
    Gfastats 1.3.6 https://github.com/vgl-hub/gfastats
    GoaT CLI 0.2.5 https://github.com/genomehubs/goat-cli
    Hifiasm 0.19.8-r603 https://github.com/chhylp123/hifiasm
    HiGlass 1.13.4 https://github.com/higlass/higlass
    lep_busco_painter 1.0.0 https://github.com/charlottewright/lep_busco_painter
    MerquryFK 1.1 https://github.com/thegenemyers/MERQURY.FK
    Minimap2 2.24-r1122 https://github.com/lh3/minimap2
    MitoHiFi 3 https://github.com/marcelauliano/MitoHiFi
    MultiQC 1.14; 1.17 and 1.18 https://github.com/MultiQC/MultiQC
    Nextflow 23.10.0 https://github.com/nextflow-io/nextflow
    PretextSnapshot N/A https://github.com/sanger-tol/PretextSnapshot
    PretextView 0.2.5 https://github.com/sanger-tol/PretextView
    samtools 1.19.2 https://github.com/samtools/samtools
    sanger-tol/ascc 0.1.0 https://github.com/sanger-tol/ascc
    sanger-tol/blobtoolkit 0.6.0 https://github.com/sanger-tol/blobtoolkit
    Seqtk 1.3 https://github.com/lh3/seqtk
    Singularity 3.9.0 https://github.com/sylabs/singularity
    TreeVal 1.2.0 https://github.com/sanger-tol/treeval
    YaHS 1.2a.2 https://github.com/c-zhou/yahs

    Articles from Wellcome Open Research are provided here courtesy of The Wellcome Trust

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