Myriapoda (Including Centipedes and Millipedes)

Abstract The Myriapoda comprises four classes of terrestrial arthropods: Chilopoda or centipedes, Diplopoda or millipedes, Symphyla and Pauropoda. Myriapods are generally found in soil and litter and have a worldwide distribution. Approximately 13 000 species are known. Myriapods share a five‐ or six‐segmented head, a single pair of antennae, uniramous (unbranched) limbs and an elongate trunk without obvious tagmatisation. The Chilopoda and Diplopoda are the largest classes, numbering respectively approximately 3000 and 10 000 described species. Centipedes are carnivorous and share poison claws derived from the first pair of trunk limbs, whereas the other classes are primarily detritivores and may be significant contributors to litter breakdown and nutrient turnover. Recent molecular phylogenetic studies indicate that the Myriapoda comprise a monophyletic group and a sister taxon to the Pancrustacea (Crustacea and Insecta). They were among the first animals to colonise land. Key Concepts: Myriapoda comprise four classes of terrestrial arthropods: Chilopoda (centipedes), Diplopoda (millipedes), Symphyla and Pauropoda. Centipedes are carnivorous, possessing unique poison claws on the first trunk (post head) segment. Millipedes are characterised by diplosegments – pairs of trunk segments sharing a single tergal plate. Millipedes, symphylans and pauropods are detritivores, occurring primarily in soils and leaf litter. Myriapods have separate sexes (gonochoristic), and sperm transfer generally involves the exchange of one or more spermatophores via specialised appendages. Molecular phylogenetic evidence supports monophyly of the Myriapoda, with the Myriapoda probably comprising a sister taxon to the Pancrustacea (Crustacea and Insecta). Both centipedes and millipedes have fossil records dating back to the mid‐upper Silurian (ca. 420 mya) and probably colonised land prior to insects. Myriapods and insects share several derived traits representing adaptations to land: tracheal systems, predominantly uniramous (unbranched) limbs and excretory Malpighian tubules opening into the hindgut.