Molecular Phylogenetics and Taxonomy of Decapod Crustaceans

Decapod crustaceans—including crabs, shrimps, lobsters and their relatives—represent one of the most diverse and ecologically significant lineages of marine and freshwater arthropods. Traditional taxonomy, largely based on morphology of adult carapaces, appendages and reproductive structures, has often been confounded by convergent forms and cryptic species. Over the past two decades, molecular phylogenetics has revolutionised our understanding of decapod evolution and classification. By comparing DNA sequences from mitochondrial and nuclear genes, researchers have reconstructed robust evolutionary trees that reveal deep divergences, unrecognised clades and points of rapid radiation. These insights have underpinned a series of taxonomic revisions at family, genus and species levels, clarifying the origins of symbiotic lifestyles, resolving species complexes in commercially important taxa, and informing conservation efforts for vulnerable lineages. The integration of molecular markers with traditional morphological characters now provides a powerful framework for a stable, predictive taxonomy that aligns ecological, biogeographic and evolutionary perspectives on decapod diversity.

Research from Nature Portfolio

Recent studies have applied DNA barcoding to larval and juvenile stages of brachyuran crabs collected in open‐sea plankton surveys. By sequencing standardised fragments of the cytochrome c oxidase subunit I and 16S rRNA genes, researchers resolved the identities of megalopa stages for more than a dozen taxa across several portunoid and xanthid families. This approach has not only enabled accurate assignment of early life stages to known species but has also revealed previously unrecorded geographic ranges and helped to map connectivity between spawning and nursery grounds, with direct implications for fisheries management and biodiversity monitoring.

Molecular Phylogenetics and Taxonomy of Decapod Crustaceans publication trend

The graph below shows the total number of articles in molecular phylogenetics and taxonomy of decapod crustaceans across all publications each year (not limited to Nature Index journals).

Technical terms

Molecular phylogenetics: Reconstruction of evolutionary relationships using DNA or RNA sequence data.

DNA barcoding: Identification of species by comparing standardised gene fragments, typically COI, across taxa.

Cytochrome c oxidase subunit I (COI): A mitochondrial gene widely used as a species‐level barcode marker.

16S rRNA: A mitochondrial ribosomal RNA gene commonly employed in crustacean phylogenies.

Monophyletic: A group comprising a common ancestor and all its descendants.

Paraphyletic: A group including a common ancestor but excluding one or more descendant lineages.

Clade: A set of organisms descended from a single ancestor on an evolutionary tree.

Taxonomic revision: The process of reevaluating and updating the classification and nomenclature of organisms based on new evidence.

References

1. DNA barcoding allows identification of undescribed crab megalopas from the open sea. Scientific Reports (2021).
2. Molecular phylogenetics of swimming crabs (Portunoidea Rafinesque, 1815) supports a revised family-level classification and suggests a single derived origin of symbiotic taxa. PeerJ (2018).
3. Mitocondrial COI and 16S rDNA sequences support morphological identification and biogeography of deep-sea red crabs of the genus Chaceon (Crustacea, Decapoda, Geryonidae) in the Eastern Central and South Atlantic Ocean. PLOS ONE (2019).
4. A new genus for Pericera septemspinosa Stimpson, 1871 and Pericera heptacantha Bell, 1836 (Crustacea, Brachyura, Majoidea), based on morphology and molecular data. Zoosystematics and Evolution (2020).