The most obvious feature of millipedes is the number of legs. The name literally means “thousand feet,” and they are commonly referred to as “thousand-leggers.” However, this is a figurative term, as the “leggiest” millipede (also the leggiest animal), Illacme plenipes (order Siphonophorida, family Siphonorhinidae), occurring in San Benito County, California, USA, has only 750 legs (375 pairs) (Cook & Loomis 1928, Shelley 1996, Shelley & Hoffman 2004). It would have to grow by another one-third (33%) and add 63 segments, carrying 252 legs (126 pairs), to become a true “thousand-legger” and a “millipede” in the literal sense.

Diversity and ecology

The Diplopoda encompasses a mind-boggling diversity of forms. Approximately 7,000 species have been described from a global fauna that is estimated, based on known degrees of endemism, to contain around 80,000 species, and we know very little about the fauna of China, which may really be immense. Millipedes are among the most ancient surviving terrestrial arthropod groups; some of the oldest fossils of land animals are diplopods, and modern forms had differentiated by the late Silurian period of the Paleozoic era, ca. 410 million years ago (Almond 1985, Shear 1992). While inhabiting all subarctic environments including deserts, they lack a waxy cuticle on the exoskeleton to function as a dessication barrier, and thus occur primarily in moist, deciduous habitats. With few exceptions, millipedes are exclusively “detritivores” (feed on decaying plant material or “detritus”) and are adapted for burrowing in the substrate, where they fill an important ecological niche by fragmenting accumulated detritus, thereby facilitating microbial decomposition and soil nutrient cycles. In tropical and subtropical forests, where earthworm populations are low, millipedes are the main debris-reducing, soil-forming organisms.

Body forms, coloration, and bioluminescence

Millipedes are relatively inflexible, “progoneate” arthropods (reproductive tracts open near the anterior end of the body) with two body divisions, a head and trunk. In most orders, the species possess a row of “ozopores” laterally, the openings of the defensive glands from which noxious or toxic fluids are secreted that repel predators, this being millipedes’ primary method of defense. They exhibit a great array of body forms that are superimposed on a basic cylindrical pattern. Many species, particularly in the orders Polydesmida and Platydesmida, possess lateral expansions of the dorsum called “paranota” that increase the surface area and impart a flattened appearance to the organism, hence the term “flat-backed” millipedes. Some species have developed the ability to volvate into a perfect ball or sphere, and are convergent in this regard with the oniscoid Isopoda of the class Crustacea that have been introduced into North America and are common in urban environments. Some millipedes are dorsolaterally smooth while others are ornamented to varying degrees, some elaborately so, with papillae, lobes, pustules, tubercles, ridges, crests, spines, and other projections; additionally, the paranota can be notched, indented, and modified to the point that they become spiniform in shape. Similarly, some species are brown or gray in color while others exhibit vivid “aposematic” coloration (colors warning about the defensive secretions) with red, orange, yellow, blue, purple, and white spots and/or transverse or longitudinal stripes; still others are uniformly reddish or turquoise. In Tulare, Kern, and Los Angeles counties, California, the species of Motyxia (Polydesmida: Xystodesmidae) bioluminesce. The entire animal lights up at night in a continuous, neon-white glow. These are the world’s only bioluminescent millipedes, and the phenomenon is thought to function as “warning luminescence,” a nocturnal equivalent of aposematic coloration. The glowing millipedes are conspicuous at night in the southern Sierra Nevada and have been described as “resembling the starry sky on a dark night.”


The class Diplopoda is defined by three autapomorphies (unique derived features): aflagellate spermatozoa, the presence of four or more apical sensory cones on each antenna, and the diplosegment condition. In the last, adjacent body somites, each carrying a pair of legs, tracheal (respiratory) openings, and a ventral nerve cord ganglion, become fused within the embryo to form diplosomites. The structures associated with the anterior of the fused somites have become relocated to the posterior somite such that in the resulting diplosegment (henceforth referred to as just “segment”), all four legs and tracheal openings and both ganglia are located in the metazonite (representing the posterior of the fused somites), while the prozonite (representing the anterior of the fused somites) lacks structures and thus inserts inside the preceding metazonite, which allows for a telescoping of segments and a more compact body form. The diplosegment condition is believed to have evolved in conjunction with millipedes’ burrowing habits, as the pushing force is more efficiently transmitted to the pushing surface when alternate segmental joints are made rigid and incompressible. The power for this pushing is generated by the legs, and at any point in time, most are in contact with the substrate in varying stages of the backstroke, pushing the millipede slowly and inexorably forward. The appendages arise midventrally, which allows for the longest possible legs and the greatest power with the least lateral extension, thereby minimizing the possibility that the appendages will extend appreciably beyond the sides of the body, where they are likely to be damaged or broken in the narrow spaces that millipedes inhabit.

Burrowing life styles

Three burrowing mechanisms are known for millipedes. The first is bulldozing, in which the millipede lowers its head and rams straight ahead, with the “collum” or 1st segment constituting the pushing surface; this method is employed by the “juliform,” or rounded/cylindrical millipedes, and involves most representatives of the orders Julida, Spirobolida, and Spirostreptida. The second is wedging, in which the anterior end inserts into a crack or crevice, and the legs, by pushing upwards and straightening, cause the opening to widen, thus allowing further penetration by the anterior end. This method is employed by the flat-backed millipedes, primarily representatives of the order Polydesmida; the paranota constitute the pushing surface and tend to split matter in a horizontal plane, like matted layers of leaves. The third mechanism is boring, in which segments of progressively greater width are dragged forward thereby widening a crevice and allowing further penetration. This method is exhibited by forms in which the anterior end is narrow and the next several segments become progressively wider, as in the order Polyzoniida. Additionally, some millipedes are believed to have undergone “habit reversal,” and abandoned burrowing for a different lifestyle. We know they evolved as burrowers because they’re millipedes and possess the diplosegment condition that evolved in conjunction with burrowing, but they no longer burrow, or do so only infrequently or feebly, and now exhibit a different lifestyle. Some, like representatives of the order Callipodida, tend to be surface active and relatively quick (quick for millipedes), and not surprisingly, such species exhibit a higher instance of carnivory than most millipedes. Effective burrowing is also believed to be possible only within certain size limits. Thus, small, narrow-bodied (<1.0 mm wide) representatives of families like the Blaniulidae (order Julida) are too weak to burrow effectively and inhabit existing cracks and crevices instead. The largest millipedes, those upwards of 30 cm (1 ft.) in length, also tend to be surface active because too great an amount of force would be needed for so large and bulky an animal to burrow an opening. Consequently, videos of savannas and deserts in eastern and southern Africa sometimes show species of the genus Archispirostreptus (Spirostreptida: Spirostreptidae), the largest known millipedes, wandering across the grassy and sandy surfaces.

Diversity in North America

The extant representatives of the class Diplopoda presently comprise 2 subclasses, 16 orders, and 145 families. Fifty-two families and ca. 914 described species inhabit the US and Canada, but the Parajulidae (order Julida), the largest family on the continent, is essentially unstudied, and some 200 undiscovered species are anticipated in this taxon alone. The higher taxa (subfamilies and orders) are distinguished primarily by aspects of the exoskeleton, the number of legs and segments, the profile and general body form, the configuration of the head, and the presence or absence, and position when present, of the sperm transfer or copulatory appendages in males.

The subclasses Penicillata & Chilognatha; the infraclass Pentazonia

The subclass Penicillata, with 160 known species (Nguyen Duy-Jacquemin & Geoffroy 2003), comprises forms in which the exoskeleton is soft, non-calcified, and covered with tufts of modified setae or bristles; males lack copulatory appendages, and reproduction occurs without contact between the sexes. Penicillates have a mechanical, rather than chemical, defense mechanism to thwart predation. The caudal bristles have apical hooks and barbs along their lengths by which they interconnect; when attacked by ants, these bristles detach, entangling and disengaging the predators, which become hopelessly entangled the more they struggle until they die (Eisner et al. 1996). All other millipedes belong to the subclass Chilognatha, which possesses a hard, calcified exoskeleton with at most only scattered setae. Males also possess reproductive appendages that are modified and specialized walking legs, and reproduction involves contact between the sexes. The infraclass Pentazonia, comprising three orders based primarily on the number of segments and whether or not the organisms volvate, contains relatively short, broad millipedes in which the five segmental sclerites (a dorsal tergite, ventral sternite, and two lateral pleurites) are separate and loosely connected by membrane. The last pair of appendages in males is modified into structures called “telopods” that either directly transfer the spermatophore to the female’s openings or function to clasp females during mating. Aspects of the configurations of the telopods constitute the primary taxonomic characters at the generic and specific levels.

The infraclass Helminthomorpha

The remaining 12 orders, containing the vast majority of species, belong to the infraclass Helminthomorpha, which comprise elongate, worm-like millipedes with varying degrees of fusion among the segmental sclerites that culminate in the condition in the Polydesmida in which they coalesce into a complete ring with no evidence of suture lines. In males, either the anterior or both pairs of legs on segment 7 (subterclass Eugnatha), or the posterior legs on segment 7 and the anterior pair on segment 8 (subterclass Colobognatha), are modified into copulatory appendages called “gonopods.” As in the Pentazonia, aspects of the configurations of the gonopods are the primary taxonomic characters at the generic and specific levels, so males are usually necessary for determinations below the familial level. Representatives of the subterclass Colobognatha have triangular or pointed heads with relatively long mouthparts that culminate in the family Siphonophoridae (order Siphonophorida), in which they are prolonged into a pointed, tubular “beak” or “rostrum,” which they are believed to insert into plant roots; some platydesmids are thought to feed on fungi using sucking mouthparts. Representatives of the subterclass Eugnatha possess chewing mouthparts and strong mandibles with which they crush detritus into small pieces. Eugnathan families are grouped into superorders based on general body form, the degree of fusion among the segmental sclerites, and the positions of gonopods in males. However, this generally accepted arrangement, detailed by Hoffman (1980) and Shelley (2003), was recently questioned by Shear et al. (2003), who provided evidence to suggest that some posterior gonopods (replacing the 9th legs or the posterior pair on segment 7) aren’t true gonopods but are modified legs that are shortened so as not to interfere with the copulatory function of the 8th legs. They further suggested that an unnamed clade exists in the Eugnatha comprising taxa in which the gonopods arise solely from the 8th legs (the anterior legs on segment 7), which, if confirmed by further research, will alter the existing taxonomy and probably also the order Spirostreptida. Diplopod taxonomy is thus a fluid science, and changes are to be expected based on new discoveries and reinterpretations of existing knowledge.

Millipedes and humans

Non-scientists are understandably concerned about whether organisms can harm people or pets, and it is important to note that, unlike centipedes, millipedes are harmless if handled properly, as they lack structures to bite, pinch, or sting. Obviously, they should not be bitten or eaten, as the defensive secretions consist of noxious compounds that would cause problems if ingested. Some secretions can discolor skin, but this wears away after a few days without lasting effect; others, however, particularly from large “juliforms,” can be quite caustic and cause skin lesions. Some large, juliform, tropical species, particularly in the Americas, forcefully expel or “squirt” their defensive secretions a meter or so (2-3 feet) and can blind chickens and dogs. Persons in the Neotropics should therefore be cautious in handling such millipedes, because these fluids are particularly caustic and very painful if squirted into the eyes. The collector of Haitobolus lethifer (Spirobolida: Rhinocricidae) in Haiti, was zapped in his left eye and experienced instantaneous, intense pain despite bathing it repeatedly in water; the eyelid and cheek swelled rapidly, closing the eye. The next day the eyelid was still swollen shut, but the swelling was reduced by bathing the eye in ice water. On the third day, the skin of the cheek, forehead, and eyelid turned dark brown and blistered where the spray concentration was greatest; the blisters persisted for a week after which the discolored skin peeled off without leaving any scars (Loomis, 1936:70-71).

The importance of taxonomic research

In any ecological or physiological study, it is essential to know the organism being investigated to ensure that the same species is employed throughout a study. Appreciation of the ecological importance of a group of organisms is directly proportional to the understanding of its taxonomy, which has advanced to the level at which broadly based biological research is feasible in only a few millipede families. Many species and genera are superficially similar such that only an experienced taxonomist can distinguish one from another, and many taxonomically complex and speciose families are uninvestigated and unavailable for other research. The Parajulidae is a classical example. It is the dominant North American family, ranging from southern Alaska and northern British Columbia-Québec to the Florida Keys and Guatemala, and exhibits a “trans-Beringian” connection with one species in Japan and China. The Parajulidae is also the dominant, and in many areas the only, representative in grassland habitats in the Central Plains, where they occur in association with decaying logs, under dung, and among whatever shelter is available. Consequently, one can reasonably conclude that parajulids are vital to the health of prairie ecosystems, but the nascent state of their taxonomy precludes their utilization in ecological research. Advancing parajulid taxonomy and opening up the family for other studies is a major research objective for the next decade.

Family-level Classification (from Shelley 2003)

The class Diplopoda consists of 2 subclasses, 16 orders, and 145 families. Fifty-three families, comprising some 217 genera and 915 nominal species, occur in North America (=the US and Canada), but hundreds more await description particularly in the families Glomeridae (Glomerida); Parajulidae (Julida); Atopetholidae (Spirobolida); Cleidogonidae, Trichopetalidae, and Striariidae (Chordeumatida); and Polydesmidae & Nearctodesmidae (Polydesmida). Of these 52 families, 39 are indigenous (17 being endemic), 5 are wholly introduced, and 5 contain both native and allochthonous species. As the Diplopoda is more speciose than the Chilopoda, the taxonomy is more complex, and additional categories are required: Infraclass, Subterclass, and Infraorders in the Polydesmida: Polydesmidea. Families represented in North America are in bold and preceded by asterisks (*); "END." denotes an endemic family, "INT." one that is wholly introduced, and "N-I" one with both native and introduced species.

Class Diplopoda de Blainville in Gervais, 1844
  Subclass Penicillata Latreille, 1831
              Order Polyxenida Verhoeff, 1934
                       Superfamily Polyxenoidea Lucas, 1840
                          Family Hypogexenidae Schubart, 1947
                          Family Lophoproctidae Silvestri, 1897
                        *Family Polyxenidae Lucas, 1840
                       Superfamily Synxenoidea Silvestri, 1923
                          Family Synxenidae Silvestri, 1923
  Subclass Chilognatha Latreille, 1802/1803
     Infraclass Pentazonia Brandt, 1833
           Superorder Limacomorpha Pocock, 1894
              Order Glomeridesmida Cook, 1895
                          Family Glomeridesmidae Latzel, 1884
           Superorder Oniscomorpha Pocock, 1887
              Order Glomerida Brandt, 1833
                          Family Doderiidae Silvestri, 1904
                        *Family Glomeridae Leach, 1815
                          Family Glomeridellidae Cook, 1896
              Order Sphaerotheriida Brandt, 1833
                          Family Sphaerotheriidae C. L. Koch, 1847
                          Family Zephroniidae Gray in Jones, 1843
     Infraclass Helminthomorpha Pocock, 1887
        Subterclass Colobognatha Brandt, 1834
              Order Platydesmida Cook, 1895
                        *Family Andrognathidae Cope, 1869
                          Family Platydesmidae DeSaussure, 1860
              Order Polyzoniida Cook, 1895
                        *Family Hirudisomatidae Silvestri, 1896
                        *Family Polyzoniidae Newport, 1844
                        *Family Siphonotidae Cook, 1895  INT.
              Order Siphonocryptida Cook, 1895
                          Family Siphonocryptidae Pocock, 1894
              Order Siphonophorida Hoffman, 1980
                        *Family Siphonophoridae Newport, 1844
                        *Family Siphonorhinidae Cook, 1895
        Subterclass Eugnatha Attems, 1898
           Superorder Juliformia Attems, 1926
              Order Julida Brandt, 1833
                       Superfamily Blaniuloidea C. L. Koch, 1847
                        *Family Blaniulidae C. L. Koch, 1847 N-I
                          Family Galliobatidae Brolemann, 1921
                          Family Okeanobatidae Verhoeff, 1942
                        *Family Zosteractinidae Loomis, 1943 END.
                       Superfamily Juloidea Leach, 1814
                        *Family Julidae Leach, 1814  INT.
                          Family Rhopaloiulidae Attems, 1926
                          Family Trichoblaniulidae Verhoeff, 1911
                          Family Trichonemasomatidae Enghoff, 1991
                       Superfamily Nemasomatoidea Bollman, 1893
                        *Family Chelojulidae Enghoff, 1991 END.
                        *Family Nemasomatidae Bollman, 1893  N-I
                          Family Pseudonemasomatidae Enghoff, 1991
                        *Family Telsonemasomatidae Enghoff, 1991  END.
                       Superfamily Paeromopodoidea Cook, 1895
                        *Family Aprosphylosomatidae Hoffman, 1961  END.
                        *Family Paeromopodidae Cook, 1895  END.
                       Superfamily Parajuloidea Bollman, 1893
                          Family Mongoliulidae Pocock, 1903
                        *Family Parajulidae Bollman, 1893
              Order Spirobolida Cook, 1895
                 Suborder Spirobolidea Cook, 1895
                        *Family Allopocockiidae Keeton, 1960
                        *Family Atopetholidae Chamberlin, 1918
                        *Family Floridobolidae Keeton, 1959  END.
                          Family Hoffmanobolidae Shelley, 2001
                          Family Messicobolidae Loomis, 1968
                          Family Pseudospirobolellidae Brölemann, 1913
                        *Family Rhinocricidae Brölemann, 1913  INT. 

                         Family Spirobolellidae Brölemann, 1913
                        *Family Spirobolidae Bollman, 1893
                          Family Typhlobolellidae Hoffman, 1969
                 Suborder Trigoniulidea Brölemann, 1913
                          Family Pachybolidae Cook, 1897
                        *Family Trigoniulidae Attems, 1909  INT.
              Order Spirostreptida Brandt, 1833
                 Suborder Cambalidea Cook, 1895
                        *Family Cambalidae Bollman, 1893
                          Family Cambalopsidae Cook, 1895
                          Family Glyphiulidae Chamberlin, 1922
                          Family Pericambalidae Silvestri, 1909
                 Suborder Epinannolenidea Chamberlin, 1922
                        *Family Choctellidae Chamberlin & Hoffman, 1950  END.
                          Family Iulomorphidae Verhoeff, 1924
                          Family Pseudonannolenidae Silvestri, 1895
                 Suborder Spirostreptidea Brandt, 1833
                       Superfamily Odontopygoidea Attems, 1909
                          Family Atopogestidae Hoffman, 1980
                          Family Odontopygidae Attems, 1909
                       Superfamily Spirostreptoidea Pocock, 1894
                          Family Adiaphorostreptidae Hoffman, 1977
                          Family Harpagophoridae Attems, 1909
                        *Family Spirostreptidae Pocock, 1894
           Superorder Nematophora Verhoeff, 1913
              Order Callipodida Pocock, 1894
                 Suborder Callipodidea Pocock, 1894
                          Family Callipodidae Bollman, 1893
                 Suborder Schizopetalidea Hoffman, 1973 
                        *Family Abacionidae Shelley, 1979
                          Family Caspiopetalidae Lohmander, 1931
                          Family Dorypetalidae Verhoeff, 1900
                          Family Paracortinidae Wang & Zhang, 1993
                        *Family Schizopetalidae Verhoeff, 1909

                 Suborder Sinocallipodidea Shear, 2000
                          Family Sinocallipodidae Zhang, 1993
              Order Chordeumatida Pocock, 1894
                 Suborder Chordeumatidea Pocock, 1894
                       Superfamily Chordeumatoidea C. L. Koch, 1847
                          Family Chordeumatidae C. L. Koch, 1847
                          ?Family Speophilosomatidae Takakuwa, 1949
                 Suborder Craspedosomatidea Cook, 1895
                       Superfamily Anthroleucosomatoidea Verhoeff, 1899
                        *Family Anthroleucosomatidae Verhoeff, 1899
                          Family Haasiidae Hoffman, 1980
                          Family Origmatogonidae Verhoeff, 1914
                          Family Vandeleumatidae Mauriès, 1970
                       Superfamily Brannerioidea Cook, 1896
                          Family Brachychaeteumatidae Verhoeff, 1911
                        *Family Branneriidae Cook, 1896  END.
                          Family Chamaesomatidae Verhoeff, 1913
                          Family Golovatchiidae Shear, 1992
                          Family Heterolatzeliidae Verhoeff, 1899
                          Family Kashmireumatidae Mauriès, 1982
                        *Family Microlympiidae Shear & Leonard, 2003  END.
                          Family Macrochaeteumatidae Verhoeff, 1914
                          Family Niponiosomatidae Verhoeff, 1941
                        *Family Tingupidae Loomis, 1966  END.
                          Family Trachygonidae Cook, 1896
                       Superfamily Cleidogonoidea Cook, 1896
                          Family Biokoviellidae Mršic, 1992
                        *Family Cleidogonidae Cook, 1896
                          Family Entomobielziidae Verhoeff, 1899
                          Family Lusitaniosomatidae Schubart, 1953
                          Family Opisthocheiridae Ribaut, 1913
                        *Family Trichopetalidae Verhoeff, 1914
                       Superfamily Craspedosomatoidea Gray in Jones, 1843
                          Family Attemsiidae Verhoeff, 1899
                        *Family Craspedosomatidae Gray in Jones, 1843  INT.
                          Family Haplobainosomatidae Verhoeff, 1909
                       Superfamily Haaseoidea Attems, 1899
                          Family Haaseidae Attems, 1899
                       Superfamily Mastigophorophylloidea Verhoeff, 1899
                          Family Altajellidae Mikhaljova & Golovatch, 2001
                          Family Hoffmaneumatidae Golovatch, 1978
                          Family Mastigophorophyllidae Verhoeff, 1899
                       Superfamily Neoatractosomatoidea Verhoeff, 1901
                          Family Neoatractosomatidae Verhoeff, 1901
                       Superfamily Verhoeffioidea Verhoeff, 1899
                          Family Verhoeffiidae Verhoeff, 1899
                 Suborder Heterochordeumatidea Shear, 2000
                       Superfamily Conotyloidea Cook, 1896
                        *Family Adritylidae Shear, 1971  END.
                        *Family Conotylidae Cook, 1896
                       Superfamily Diplomaragnoidea Attems, 1907
                          Family Diplomaragnidae Attems, 1907
                       Superfamily Heterochordeumatoidea Pocock, 1894
                          Family Eudigonidae Verhoeff, 1914
                          Family Heterochordeumatidae Pocock, 1894
                          Family Megalotylidae Golovatch, 1978
                          Family Metopidiotrichidae Attems, 1907
                          ?Family Peterjohnsiidae Mauriès, 1987
                       Superfamily Pygmaeosomatoidea Carl, 1941
                          Family Lankasomatidae Mauriès, 1978
                          Family Pygmaeosomatidae Carl, 1941
                 Suborder Striariidea Cook, 1896
                       Superfamily Caseyoidea Verhoeff, 1909
                       *Family Caseyidae Verhoeff, 1909
                        *Family Urochordeumatidae Silvestri, 1909  END.
                       Superfamily Striarioidea Bollman, 1893
                        *Family Apterouridae Loomis, 1966  END.
                        *Family Rhiscosomididae Silvestri, 1909  END.
                        *Family Striariidae Bollman, 1893  END.
              Order Stemmiulida Cook, 1895
                          Family Stemmiulidae Pocock, 1894
           Superorder Merocheta Cook, 1895
              Order Polydesmida Pocock, 1887
                 Suborder Leptodesmidea Brölemann, 1916
                       Superfamily Chelodesmoidea Cook, 1895
                          Family Chelodesmidae Cook, 1895
                       Superfamily Platyrhacoidea Pocock, 1895
                          Family Aphelidesmidae Brölemann, 1916
                          Family Platyrhacidae Pocock, 1895
                       Superfamily Rhachodesmoidea Carl, 1903
                          Family Rhachodesmidae Carl, 1903
                          Family Tridontomidae Loomis & Hoffman, 1962
                       Superfamily Sphaeriodesmoidea Humbert & DeSaussure, 1869
                          Family Campodesmidae Cook, 1896
                          Family Holistophallidae Silvestri, 1909
                        *Family Sphaeriodesmidae Humbert & DeSaussure, 1869
                       Superfamily Xystodesmoidea Cook, 1895
                        *Family Eurymerodesmidae Causey, 1951  END.
                        *Family Euryuridae Pocock, 1909  END.
                          Family Gomphodesmidae Cook, 1896
                          Family Oxydesmidae Cook, 1895
                        *Family Xystodesmidae Cook, 1895
                 Suborder Dalodesmidea Hoffman, 1980
                          Family Dalodesmidae Cook, 1896
                          Family Vaalogonopodidae Verhoeff, 1940
                 Suborder Strongylosomatidea Brölemann, 1916
                        *Family Paradoxosomatidae Daday, 1889  INT.
                 Suborder Polydesmidea Pocock, 1887
                    Infraorder Oniscodesmoides Simonsen, 1990
                       Superfamily Oniscodesmoidea DeSaussure, 1860
                          Family Dorsoporidae Loomis, 1958
                          Family Oniscodesmidae DeSaussure, 1860
                       Superfamily Pyrgodesmoidea Silvestri, 1896
                          Family Ammodesmidae Cook, 1896
                          Family Cyrtodesmidae Cook, 1896
                        *Family Pyrgodesmidae Silvestri, 1896  N-I
                    Infraorder Polydesmoides Pocock, 1887
                       Superfamily Haplodesmoidea Cook, 1895
                          Family Doratodesmidae Cook, 1896
                        *Family Haplodesmidae Cook, 1895  INT.
                       Superfamily Opisotretoidea Hoffman, 1980
                          Family Opisotretidae Hoffman, 1980
                       Superfamily Polydesmoidea Leach, 1815
                          Family Cryptodesmidae Karsch, 1880
                        *Family Polydesmidae Leach, 1815  N-I
                       Superfamily Trichopolydesmoidea Verhoeff, 1910
                          Family Fuhrmannodesmidae Brölemann, 1916
                        *Family Macrosternodesmidae Brölemann, 1916  N-I
                        *Family Nearctodesmidae Chamberlin & Hoffman, 1950 END
                          Family Trichopolydesmidae Verhoeff, 1910
     Helminthomorpha incertae sedis
              Order Siphoniulida Cook, 1895
                          Family Siphoniulidae Pocock, 1894

Millipede Research

While some genera and species have been proposed for forms in other regions of the world, the objective of my faunistic and alpha taxonomic research for over 35 years has been the elucidation of the North American (NA) diplopod fauna. This primarily covers taxa in the United States and Canada, but some extend southward into Mexico. It is divided into five categories, two being complete or nearly so, which are described briefly below along with future research plans.


1. The Family Xystodesmidae

The initial emphasis was the Xystodesmidae (Polydesmida), which occurs in the following regions of NA plus ones in Asia and the Mediterranean coast of Europe, Africa, and the Middle East: the eastern US and southern Ontario & Québec, Canada, east of the Central Plains (the "eastern" fauna); from southern Texas and New Mexico to El Salvador (the "meso-American" fauna); and along the Pacific Coast from Los Angeles to southern Alaska, with a disjunct area in eastern Oregon & Washington, northern Idaho, western Montana, and doubtlessly also adjacent British Columbia (the "western" fauna)(Fig. 1). This work proceeded in two stages and was built upon the foundation laid by Dr. R. L. Hoffman, Virginia Museum of Natural History, in numerous revisionary studies. From 1971-1987, the focus was the “eastern” taxa, during which the phenomenon of “mosaic complexes” was discovered and addressed as part of a revision of the genera Sigmoria and Deltotaria (Shelley & Whitehead 1986); from 1989-1997, the focus was the “western” taxa and those in Texas and New Mexico. A total of 11 new genera and 83 species & subspecies were described throughout NA and 15 established genera were revised, such that today the entire, known US and Canadian fauna has been reviewed except for two widespread “eastern” genera -- Nannaria and Apheloria -– and a work detailing the overall distribution of Apheloria and occurrences west of the Mississippi River is in press (Shelley & McAllister in press)

Fig. 1. Distribution of the Xystodesmidae in North and Central America



2. The Family Eurymerodesmidae.

This complex family occurs in the southeast and extends westward into central Texas and Oklahoma, and northward to Nebraska (Fig. 2). With only one genus and 28 species and subspecies, it is the dominant representative of the order Polydesmida in prairie ecosystems in the Central Plains. The Eurymerodesmidae belongs to the Leptodesmidea, as does the Xystodesmidae and a dozen other families, but its affinities are uncertain; it exhibits a host of autapomorphies but no clear synapomorphies with another taxon. Another mosaic complex, its study provided the opportunity to examine the extent of this phenomenon throughout the Diplopoda as a whole (Shelley 1990a).

Fig. 2. Distribution of the Eurymerodesmidae



3. Revisions and Synoptic Studies of Other Orders and Families.

While the research on the Xystodesmidae and the Eurymerodesmidae was in progress, studies were also proceeding on other NA taxa to advance the goal of documenting the continental fauna. They have involved every indigenous order in North America except Polyxenida and Glomerida.  The entire Western Hemisphere faunas of the order Callipodida, family Paeromopodidae (Julida), and subfamily Desmoninae (Polydesmida: Sphaeriodesmidae) have been studied, and the orders Siphonophorida and Polyzoniida have been revised to the extents possible today. Though incompletely reviewed, two polydesmidan families – Nearctodesmidae and Pyrgodesmidae – and one in the order Chordeumatida (Caseyidae) have been examined in depth as have the tribe Aniulini (Julida: Parajulidae) and the representatives of the Polydesmidae occurring west of the Continental Divide. The following additional genera have also been revised: Anelus (Spirobolida: Allopocockiidae), Onychelus and Piedolus (Spirobolida: Atopetholidae), Cambala (Spirostreptida: Cambalidae), Auturus (Polydesmida: Euryuridae), and Brachycybe (Platydesmida: Andrognathidae).


4. Faunal Treatments.

It is important to consolidate information from disparate taxonomic studies so that others can grasp total faunas and the scope of the taxa that exist in the field. This category includes detailed faunistic studies with anatomical, habitat, and other information on each species, and “annotated checklists,” which are basically taxonomic lists with a modicum of additional information. Faunistic studies have been published on the eastern Piedmont and Kings Mountain regions of North Carolina (Shelley 1978a, Filka & Shelley 1980) and Canada (the eastern, western, and central regions and the country as a whole) (Shelley 1988, 1990b, 2002a; Shelley & LeSage 1989). Checklists have been prepared for the Coastal Zone of South Carolina, North Carolina as a whole, Florida, and California (Shelley 1978b, 2000a, 2001a, 2002b).


5. Distributional Studies.

Field work in North America by myself and colleagues has yielded innumerable samples of relatively common & abundant indigenous millipedes from areas where there were few if any records. Existing distributional concepts are thus obsolete, and works have been published updating them. These include publications on Scytonotus granulatus (Polydesmida: Polydesmidae), Narceus (Spirobolida: Spirobolidae), Virgoiulus minutus (Julida, Blaniulidae), the only indigenous blaniulid, Brachycybe (Platydesmida: Andrognathidae),  Apheloria (Polydesmida: Xystodesmidae), and Opiona columbiana (Chordeumatida: Caseyidae); one is planned on Aniulus garius (Julida: Parajulidae), and others will develop as material becomes available (McAllister et al. 2005, Shelley & McAllister 2006; Shelley et al. 2005a, b, c, 2006, in press).


6. Miscellaneous Research.

Outside the NA focus, species and genera of particular interest have been described or redescribed in the following orders and families: the polydesmidan families Paradoxosomatidae (a form from Namibia), Chelodesmidae (forms from Ecuador, Peru, Colombia, Trinidad and Tobago, and the Bahamas), Platyrhacidae (a species ranging from Nicaragua to Panama), and Rhachodesmidae and Pyrgodesmidae (both for species in Mexico) and the polyzoniidan family Hirudisomatidae (Mexico and Nepal); additionally, the new spirobolidan family Hoffmanobolidae was proposed for a form in Mexico. Through collaborations with colleagues, the first male in the order Siphoniulida has been characterized, this being the most poorly known and rarest order in the class (Sierwald et al. 2003); the suborder Sinocallipodidea (Callipodida) also has been addressed (Shear et al. 2003) as has the lone African representative of the order Siphonophorida (Shelley & Hoffman 2004). At the request of colleagues at the Bishop Museum, Honolulu, seven papers were developed on the Hawaiian fauna, most of which is introduced (Shelley 1998a-d, Shelley & Swift 1998, Shelley et al. 1998, Shelley & Golovatch 2000); the only known elements of the Hawaiian fauna that have not been treated are the representatives of the introduced family Spirobolellidae (Spirobolida) and the indigenous genus Nannolene (Spirostreptida: Cambalidae). As exotic millipedes receive little attention in general, works were produced on introduced representatives of the family Paradoxosomatidae (Polydesmida) on Pacific Islands and two species in the family Trigoniulidae (Spirobolida) that have been introduced to islands throughout the world and also to Africa and North, South, & Central America (Shelley 1998e, Shelley & Lehtinen 1999, Shelley et al. 2006). The most important efforts were geared toward advancing Diplopodology in general. I led a collaborative effort to prepare a second generic and familial Nomenclator (Shelley et al. 2000) and individually developed a new family-level classification for the class (Shelley 2003); a third "Nomenclator" is in preparation.


One non-scientific effort that warrants mention here is the popularized booklet on centipedes and millipedes (Shelley 1999), produced for the same reason as this website, to disseminate accurate information on these arthropods to non-biologists.  Booklets are available from me for free.


Future Research Plans.

Future taxonomic, faunistic, and distributional research will focus on five main topics, though other activities may arise. Results, updates, and new information will be presented periodically on this web site.


a) The Family Parajulidae.

The major focus for the next decade will be the family Parajulidae (Julida), the dominant, most taxonomically complex NA family that has largely been ignored; there is also one species in Asia (Japan & China), so it exhibits a “trans-Beringian connection.” The Parajulidae may contain upwards of 200 undescribed species, and it is the only indigenous family that occurs in Alaska and every county, state, and physiographic province in the lower 48 states; in Canada, it extends from the Queen Charlotte and Vancouver Islands, British Columbia, to southeastern Québec. North-south, the family ranges from Yakutat, Alaska and James Bay, Ontario, to Guatemala (Fig. 3). Advancing the knowledge and taxonomy of this family is vital to the goal of documenting the continental diplopod fauna as a whole. The initial emphasis has been on the tribe Aniulini, which ranges from the Atlantic Coast to Arizona, Alberta, and Québec; five papers have been published (Shelley 2000b-c, 2001b, 2002c, 2004) in which 15 species and subspecies have been described, and a summary one is in preparation. Beyond this tribe, the plan is to work generally from east to west across the continent revising genera and tribes in the process. Recently, the new tribe Nesoressini was proposed for Nesoressa crawfordi, a monotypic new genus & species that occurs primarily at high elevations on isolated mountains in central New Mexico (Shelley & Medrano 2006), and a new genus is being proposed for a new form in Florida (Shelley, in submission). 

Fig. 3. Distribution of the Parajulidae in North and Central America


b) “Micro-Nearctodesmids.”

The genera Phreatodesmus, Tidesmus, and Oodedesmus have been erected for small-bodied polydesmidans that occur around springs and in transiently moist spots in southwestern deserts (usually during cool weather seasons). They and undiagnosed genera display diagnostic features of the families Nearctodesmidae & Macrosternodesmidae, and may link with the form in Jalisco & Colima, Mexico, that Shelley (1994) assigned to the Nearctodesmidae. A related form with a strong, pungent aroma, Leonardesmus injucundus Shelley & Shear, 2006, has recently been described from the Olympic Peninsula of Washington.


c) Ordinal Distributions and Mappings.

In the study on the Sinocallipodidea, Shear et al. (2003) presented a full distribution map of the order Callipodida. Comparable efforts are in progress for the other 15 orders.


d) Fauna of the “Ark-La-Tex” Region.

Collaborative research since 2001 with C. T. McAllister in Texas has greatly enhanced knowledge of the fauna of the region containing Arkansas, Louisiana, Texas, and Oklahoma. It has also significantly advanced faunal knowledge of the area between the Mississippi River and the Central Plains, where distributions are typically poorly documented. One new species, Abacion wilhelminae (Callipodida: Abacionidae), has been described (Shelley et al. 2003a) and several new species in the order Chordeumatida await description. Additionally, the ranges of a half-dozen or so species have been dramatically extended.  Papers have been published on Pleuroloma flavipes and the tribe Pachydesmini (Polydesmida: Xystodesmidae) (Shelley et al. 2003b, Shelley & McAllister 2006), Scytonotus granulatus (Polydesmida: Polydesmidae) (Shelley et al. 2005), Virgoiulus minutus (Julida: Blaniulidae) (McAllister et al. 2005), and Auturus l. louisianus (Polydesmida: Euryuridae) (McAllister et al. 2006). This research will continue and expand into the Plains proper from Kansas northward.

e) The fauna of Alaska and northern British Columbia (BC), Canada.

Before 2006, Alaska (AK) was the only significant part of NA that had never been investigated by a knowledgeable diplopodologist. Only 20 or so samples existed from the state, all collected incidentally by non-specialists researching other organisms, and most were from the southern extremity of the Panhandle. Coastal forested environments from Anchorage/Kenai Peninsula to the southern Panhandle are comparatively warm & moist and likely harbor diverse faunas, particularly the true rainforests that harbor a wealth of species from coastal British Columbia to Oregon.  Alaska is also biogeographically significant because of its role in faunal exchange between NA & Asia through the former Bering Land Bridge, and 7 millipede families in BC and the northwestern states demonstrate "trans-Beringian connections" and also occur in east Asia (Russia, Japan, Korea, Manchuria). Phylogenetically significant forms, anatomical "missing links," conceivably await discovery in suitable Alaskan habitats, which may also harbor undiscovered forms of endemic Asian taxa that have not dispersed farther south and hence are unknown from NA. Through generous support from the National Geographic Society, I spent 6 weeks in Alaska in summer 2006 searching for and collecting millipedes and was accompanied on part of this expedition by M. Medrano, University of New Mexico. One new species was discovered along with astonishing range extensions of families known previously from southwestern BC and the northwestern US, and two publications are in press (Shear & Shelley in press, Shelley et al. in press). If funding is obtained, a second expedition will be conducted in 2007 that will extend into northern coastal BC, primarily to try to confirm the exciting discovery of the tropical order Glomeridesmida on an island near Prince Rupert (Shelley et al., in press)  Further discoveries of high biogeographical and phylogenetic significance are plausible in this, the northwesternmost corner of North America, and will be announced on this website.  

Selected References

Filka, M. E., & R. M. Shelley. 1980. The milliped fauna of the Kings Mountain region of North Carolina (Arthropoda: Diplopoda). Brimleyana, 4:1-42.

McAllister, C.T., & R.M. Shelley. 2005. Discovery of the milliped, Auturus louisianus louisianus (Chamberlin, 1918), in Texas (Polydesmida: Euryuridae). Ent. News, 116(3):187-188.

____, ____, H. Enghoff, & Z. D. Ramsey. 2005. Distribution of the milliped Virgoiulus minutus (Brandt, 1841) (Julida: Blaniulidae).  Western North American Nat., 65(2):258-266.

Shear, W.A., & R.M. Shelley. 2007. Tingupa tlingitorum, n. sp., a new milliped species from Haines, Alaska, USA, with notes on the generic distribution and a revised key to species (Chordeumatida: Tingupidae). Zootaxa, in press.

____, ____, & H. Heatwole. 2003. Occurrence of the milliped Sinocallipus simplipodicus Zhang, 1993 in Laos, with reviews of the Southeast Asian and global callipodidan faunas, and remarks on the phylogenetic position of the order (Callipodida: Sinocallipodidea: Sinocallipodidae). Zootaxa, 365:1-20.

Shelley, R. M. 1978a. Millipeds of the eastern Piedmont region of North Carolina, U.S.A. (Diplopoda). J. Nat. Hist., 12:37-79.

_____. 1978b. Diplopoda, pp. 222-223, In: Zingmark, R. G., ed., An Annotated Checklist of the Biota of the Coastal Zone of South Carolina. Univ. of South Carolina Press, 364 pp.

_____. 1988. The millipeds of eastern Canada (Arthropoda: Diplopoda). Can. J. Zool., 66:1638-1663.

_____. 1990a (1989). Revision of the milliped family Eurymerodesmidae (Polydesmida: Chelodesmidea). Mem. American Entomol. Soc. No. 37:1-112.

_____. 1990b. A new milliped of the genus Metaxycheir from the Pacific Coast of Canada (Polydesmida: Xystodesmidae), with remarks on the tribe Chonaphini and the western Canadian and Alaskan diplopod fauna. Can. J. Zool., 68:2310-2322.

_____. 1994. The milliped family Nearctodesmidae in northwestern North America, with accounts of Sakophallus and S. simplex Chamberlin (Polydesmida). Can. J. Zool., 72:470-495.

_____. 1998a. Occurrence of the milliped Glyphiulus granulatus (Gervais) in the Hawaiian Islands (Spirostreptida: Cambalidea: Cambalopsidae). Bishop Mus. Occ. Paps. No. 56:36-37.

_____. 1998b. Interception of the milliped Rhinotus purpureus (Pocock) at Quarantine, and potential introduction of the order and family into the Hawaiian Islands (Polyzoniida: Siphonotidae). Bishop Mus. Occ. Paps. No. 56:54-55.

_____. 1998c. Occurrence of the milliped Trigoniulus corallinus (Gervais) on O’ahu and Kaua’i (Spirobolida: Pachybolidae: Trigoniulinae). Bishop Mus. Occ. Paps. No. 56:55-57.

_____. 1998d. Introduced millipeds of the family Paradoxosomatidae on Pacific Islands (Diplopoda: Polydesmida). Arthropoda Selecta, 7(2):81-94.

_____. 1999. Centipedes and Millipedes, with emphasis on North American fauna. Kansas School Nat., 45(3):1-15.

_____. 2000a. Annotated checklist of the millipeds of North Carolina (Arthropoda: Diplopoda), with remarks on the genus Sigmoria Chamberlin (Polydesmida: Xystodesmidae). J. Elisha Mitchell Sci. Soc., 116(3):177-205.

_____. 2000b. Parajulid studies II. The subgenus Hakiulus Chamberlin (Julida: Parajulidae: Parajulinae: Aniulini). Myriapodologica, 6(14):121-145.

_____. 2000c. Parajulid studies III. The genus Gyniulus Loomis (Parajulinae: Aniulini). Myriapodologica, 7(3):19-28.

_____. 2001a (2000). Annotated checklist of the millipeds of Florida (Arthropoda: Diplopoda). Insecta Mundi, 14(4):241-251.

_____. 2001b. A synopsis of the milliped genus Aniulus Chamberlin (Julida: Parajulidae: Parajulinae: Aniulini). Texas Mem. Mus. Speleol. Monogs., 5:73-94.

_____. 2002a. The millipeds of central Canada (Arthropoda: Diplopoda), with reviews of the Canadian fauna and diplopod faunistic studies. Can. J. Zool., 80:1863-1875.

_____. 2002b. Annotated checklist of the millipeds of California (Arthropoda: Diplopoda). Western North American Nat. Mon., 1:90-115.

_____. 2002c. The milliped genus Oriulus Chamberlin (Julida: Parajulidae). Can. J. Zool., 80:100-109.

_____. 2003 (2002). A revised, annotated, family-level classification of the Diplopoda. Arthropoda Selecta, 11(3):187-207.

_____. 2003. A new polydesmid milliped genus and two new species from Oregon and Washington, USA, with a review of Bidentogon Buckett and Gardner, 1968, and a summary of the family in western North America (Polydesmida: Polydesmidae).  Zootaxa, 296:1-12.

_____. 2003. Redescription of the milliped Amphelictogon subterraneus bahamiensis Chamberlin, 1918, with an assessment of the family Chelodesmidae in the Bahamas (Polydesmida: Leptodesmidea). Zootaxa, 180:1-8.

_____. 2004a (2002). Parajulid studies V. The genera Pseudojulus Bollman and Arvechambus Causey (Parajulinae: Aniulini). Insecta Mundi, 16(4):191-204.

_____.  2004b.  The milliped family Pyrgodesmidae in the continental United States, with the first record of Poratia digitata (Porat) from the Bahamas (Polydesmida).  J. Nat. Hist., 38(9):1159-1181.

_____.  in submission. Arvechamboides ocala, n. gen., n. sp., a new aniulinine milliped from peninsular Florida, USA (Julida: Parajulidae). submitted to Zootaxa

_____, & D. R. Whitehead. 1986. A reconsideration of the milliped genus Sigmoria, with a revision of Deltotaria and an analysis of the genera in the tribe Apheloriini (Polydesmida: Xystodesmidae). Mem. American Entomol. Soc. No. 35:1-223.

_____, & S. F. Swift. 1998. The milliped order Julida in the Hawaiian Islands. Bishop Mus. Occ. Paps. No. 56:38-43.

_____, & P. T. Lehtinen. 1999. Diagnoses, synonymies, and occurrences of the pantropical millipeds, Leptogoniulus sorornus (Butler) and Trigoniulus corallinus (Gervais) (Spirobolida: Pachybolidae: Trigoniulinae). J. Nat. Hist., 33:1379-1401.

_____, & S. I. Golovatch. 2000. The milliped family Haplodesmidae in the Hawaiian Islands, with records of Prosopodesmus jacobsoni from Florida and Louisiana (Diplopoda: Polydesmida). Bishop Mus. Occ. Paps., 64:48-49.

_____, & R. L. Hoffman.  2004. A contribution on the South African milliped genus Nematozonium Verhoeff, 1939 (Siphonophorida: Siphonorhinidae). African Ent., 12(2):217-222.

_____, & C. T. McAllister.  2006.  Composition and distribution of the milliped tribe Pachydesmini west of the Mississippi River (Polydesmida: Xystodesmidae).  Western North American Nat., 66(1):45-54.

_____, & M.F. Medrano. 2006. Nesoressa crawfordi, n. gen., n. sp., a montane island milliped in New Mexico, USA; proposal of the new tribe Nesoressini and a preliminary cladogram of the lineage "Aniulina" (Julida: Parajulidae). Zootaxa, 1285:31-50.

____, & W.A. Shear. 2006. Leonardesmus injucundus, n. gen., n. sp., an aromatic, small-bodied milliped from Washington State, USA, and a revised account of the family Nearctodesmi-dae (Polydesmida). Zootaxa, in press.

____, & C.T. McAllister. 2006. Distribution of the milliped genus Apheloria virginiensis (Drury, 1770) west of the Mississippi River; First record of A. v. reducta Chamberlin, 1939, from Kansas (Polydesmida: Xystodesmidae).

_____, S. B. Bauer, & S. F. Swift. 1998. The milliped family Paradoxosomatidae in the Hawaiian Islands (Diplopoda: Polydesmida). Bishop Mus. Occ. Paps. No. 56:43-53.

_____, P. Sierwald, S. B. Kiser, & S. I. Golovatch. 2000. Nomenclator generum et familiarum Diplopodorum II. A List of the Genus and Family-Group Names in the Class Diplopoda from 1958 through 1999. Pensoft Publishers, Sofia, Bulgaria, 167 pp.

_____, & G. B. Edwards. 2002. Introduction of the milliped family Rhinocricidae in Florida (Spirobolida).  Ent. News, 113(4):270-274.

_____, C. T. McAllister, & J. L. Hollis. 2003a. A new milliped of the genus Abacion Rafinesque, 1820 from Arkansas, U. S. A. (Callipodida: Abacionidae). Zootaxa, 170:1-7.

____, ____, & S. B. Smith. 2003b. Discovery of the milliped Pleuroloma flavipes (Polydesmida: Xystodes-midae) in Texas, and other records from west of the Mississippi River. Ent. News, 114(1):2-6.

____, ____, & Z. D. Ramsey. 2005a. Discovery of the milliped, Scytonotus granulatus (Say, 1821) in Okla-homa, with a new record from Alabama and a review of its distribution (Polydesmida: Polydesmi-dae).  Western North American Nat., 65(1):112-117.

____, ____, & T. Tanabe. 2005b. A synopsis of the milliped genus Brachycybe Wood, 1864 (Platydesmida: Andrognathidae). Fragmenta Faunistica, 48(2):137-166.

____, ____, & M.F. Medrano. 2006. Distribution of the milliped genus Narceus Rafinesque, 1820 (Spirobolida: Spirobolidae): Occurrences in New England and west of the Mississippi River, and a summary of peripheral localities; first records from Connecticut, Delaware, Maine, and Minnesota. Western North American Nat., 66(3):374-389.

____, R. Carmany, & J. Burgess. 2006. Introduction of the milliped, Trigoniulus corallinus (Gervais), in Florida (Spirobolida: Trigoniulidae). Ent. News, 117(2):239-241.

____, R.A. Cannings, P.T. LePage, & K.J. White. 2006. A glomeridesmid milliped in Canada (Diplopoda: Glomeridesmida). Ent. News, in press.

____, W.A. Shear, W.P. Leonard, & K. Ovaska. 2007. Opiona columbiana Chamberlin, 1951: Distribution extensions into the Alexander Archipelago, Alaska, and eastern & southern Washington State, USA; new records from Vancouver Island, British Columbia.  Check List, in press.

Sierwald, P., W. A. Shear, R. M. Shelley, & J. E. Bond. 2003. Millipede phylogeny revisited in the light of the enigmatic order
          Siphoniulida. J. Zool. Syst. Evol. Res., 41:87-99.