Tickets

Milli-PEET: The class Diplopoda

    Millipedes are of outstanding ecological importance and play a crucial role in the decomposition of leaf litter and in the nutrient cycling within the soil. With an estimated total of more than 80,000 extant species, the ancient class Diplopoda (millipedes) is the third most diverse class of terrestrial arthropods, following Insecta and Arachnida. Despite their ecological importance, millipedes remain one of the poorest studied animal groups on the planet. Only about 12,000 millipede species have been formally described, but we do not have a catalog to keep track of described species and their distribution. Millipede biology and the morphology of the described species are inadequately explored. Millipedes never attracted many researchers; presently the expertise for this group is at the brink of extinction. The lack of comprehensive identification tools, such as illustrated keys, compounds the problem. The research community consequently avoids millipedes as model organisms for inquiries into evolutionary, biogeographical, and behavioral research, while also largely overlooking them in conservation studies.

    With NSF support, Drs. Petra Sierwald, Jason E. Bond and William A. Shear developed a program to (a) advance millipede systematics, (b) train new millipede taxonomists, (c) develop tools to make millipedes more easily accessible for future research and (d) advance electronic forms of data capture of specimen collections and the original scientific millipede literature.

    Brought to you by the Field Museum of Natural History and PEET (Partnerships for Enhancing Expertise in Taxonomy), a program of the National Science Foundation, USA.

    Additional Links

     

    Millipedes (Diplopoda) are classified together with the centipedes (Chilopoda), the pauropods and the symphylans in the group Myriapoda.

    The monophyly of the Myriapoda has long been debated. Several morphological characters, e.g., the position of the genital opening (anterior in Diplopoda, Pauropoda and Symphyla; posterior in Chilopoda), the number of mouth parts (two in Diplopoda and Pauropoda; three in Symphyla and Chilopoda) suggest conflicting relationships. Numerous new studies are underway, many of them employing molecular as well as morphological characters. Currently, arthropod relationships (e.g., the Pancrustacea hypothesis) are the main focus of many systematic studies.

    The Pauropoda are so far the undisputed sistergroup to the Diplopoda, mainly supported by two shared characters, the gnathochilarium of the mouth parts and the legless first trunk segment, the collum. The 16 orders of millipedes remained remarkably stable (with the exception of conflicting classifications between parts of the Spirostreptida and Julida). Hoffman (1980, see Bibliography) gives an excellent and detailed review of the classification history of the Diplopoda. For a recent overview see Sierwald & Bond, 2007. Annual Review of Entomology 57, 401-420.

    The following files contain cladograms representing currently used classifications. They are provided for information only and are not intended as new phylogenetic hypotheses.

    1. Relationship overview: supraordinal clades
    2. Ordinal relationships of the Diplopoda (Enghoff 1981)
    3. Ordinal cladogram of the Diplopoda, reflecting the classification used by Hoffman (1980)
    4. Ordinal cladogram of the Diplopoda under the inclusion of the enigmatic order Siphoniulida (Sierwald et al., 2003)
    5. Relationships within the Helminthomorpha as suggested by molecular data employed by Regier & Shultz (2001)
    6. Ordinal relationships inferred from a Bayesian analysis of nucleotides (Regier et al., 2005)
    7. Ordinal relationships inferred from a parsimony analysis of amino acids, strict consensus (Regier et al., 2005)
    8. Ordinal relationships in the Diplopoda and Chilopoda (Regier et al., 2005) based on morphological characters
    9. Tribal relationships within the Order Sphaerotheriida (Hoffman, 1976, 1980; Jeekel, 1974, Mauriès 2001, and Wesener & Sierwald, 2005)
    10. Tribal relationships of the Paradoxosomatidae and Polydesmida (Jeekel, 1968; Hoffman, 1980; Golovatch, 1984; Golovatch & Enghoff, 1994)
    11. Description and putative apomorphies of millipede clades

    A bibliography of this material is also available as a downloadable PDF.