Taxonomic Diversity and Phylogenetics of Millipedes

The class Diplopoda encompasses over 12 000 described species arranged in sixteen orders, with diversity expressed through segmental paranota, specialized gonopods, chemical defence glands and varied chaetal patterns. Millipede taxonomy has historically relied on morphological characters, but the integration of molecular data—mitochondrial genomes, transcriptomes and multi‐locus markers—has transformed our understanding of interordinal relationships and lineage diversification. Phylogenetic frameworks now reveal ancient splits, convergent adaptations and cryptic species radiations across all continents except Antarctica. Advances in genome sequencing have elucidated the timing of major divergences and the stepwise evolution of chemical defences. Continued synthesis of field surveys, high‐throughput sequencing and rigorous phylogenetic methods is resolving long-standing classification challenges and illuminating the evolutionary drivers of millipede diversity.

Research from Nature Portfolio

Complete mitochondrial genomes from key taxa have provided high-resolution markers for phylogenetic inference, uncovering conserved gene orders and A + T bias in base composition. Analyses of protein-coding genes under purifying selection have refined ordinal and family-level trees using both Bayesian inference and maximum likelihood approaches. In parallel, phylogenomic studies of defensive chemistry have traced the emergence of benzoquinone and phenolic pathways, demonstrating that complex chemical defences arose in a stepwise manner through the recruitment of enzymatic modules. Independent lineages exhibit distinct secondary metabolite profiles, highlighting chemical innovation as a recurrent theme in millipede evolution.

Taxonomic Diversity and Phylogenetics of Millipedes publication trend

The graph below shows the total number of articles in taxonomic diversity and phylogenetics of millipedes across all publications each year (not limited to Nature Index journals).

Technical terms

Mitogenome: The complete set of mitochondrial DNA genes (protein-coding, tRNA and rRNA), used as molecular markers in phylogenetic studies.

Purifying selection: Evolutionary pressure that removes deleterious mutations, maintaining functional integrity of genes across lineages.

Phylogenomics: The reconstruction of evolutionary relationships using genome-scale data, often combining nuclear and organellar sequences.

Synapomorphy: A shared derived character state that unites a monophyletic group and distinguishes it from other taxa.

Gonopod: A specialised male reproductive appendage, derived from a walking leg, frequently used as a key diagnostic character in millipede taxonomy.

References

1. Characterization of the complete mitochondrial genome of Spirobolus grahami (Diplopoda: Spirobolidae) with phylogenetic analysis. Scientific Reports (2024).
2. Step-wise evolution of complex chemical defenses in millipedes: a phylogenomic approach. Scientific Reports (2018).
3. Millipede Taxonomy after 250 Years: Classification and Taxonomic Practices in a Mega-Diverse yet Understudied Arthropod Group. PLOS ONE (2012).
4. Ordinal-Level Phylogenomics of the Arthropod Class Diplopoda (Millipedes) Based on an Analysis of 221 Nuclear Protein-Coding Loci Generated Using Next-Generation Sequence Analyses. PLOS ONE (2013).
5. Phylogenetic Systematics of the Millipede Family Xystodesmidae. Insect Systematics and Diversity (2021).