Description:
Unique and basal group of millipedes with soft, non-calcified body segments decorated with defensive bristles. All species are quite small with none greater than 7mm in length. They have 11-13 body segments and no more than 17 pairs of legs and the males lack gonopods and telopods. They also lack defensive glands and instead use their bristles, which are barbed and detach easily, for defense.

Reproduction: 

Reproduction happens without direct copulation and either involves the deposit and subsequent picking up of a spermatophore or in many species males are absent altogether and reproduction occurs via parthenogenesis. 

Range:

Worldwide distribution. Generally found under the bark of dead trees and logs 

Diet: 

Polyxenids have been reported to feed on soil yeasts, lichens, and algae.

Group members:

There are at least 86 species in four families worldwide and 2 families with 3 genera and 8 species described in the US  

Description:

Glomerida is one of two orders of pill millipedes. Most species are quite small, with body sizes ranging from ~5-20mm. They have 12 body segments with 17-19 pairs of legs (depending on sex). The rear legs in males, referred to as telopods, are enlarged and used in mating. The second and third tergites can also be fused in some species and the 11th tergite may be small and hidden. Members of the group are capable of volvation (aka conglobation), rolling into a tight defensive ball and superficially resemble some isopods. The second and last tergites are enlarged to generate a protective shield while the collum is reduced to a small plate above the head. The head and collum are protected by the larger tergites during volvation. 

Unlike most millipedes, the defensive glands of glomerida are located in the central dorsal region with a single opening (ozopore) on tergites 4-11.

Reproduction: 

Reproduction occurs through direct mating and the males use their telopods to clasp females.

Range:

They are found primarily in the northern hemisphere and are therefore called the northern pill millipedes.

Diet: 

Like most millipedes glomerida are detritivores and feed on decaying plant matter and most live in leaf litter or duff

Group members:

There are approximately 30 genera and at least 280 species worldwide with 2 genera and 3 species known from the US. 

Description:

Sphaerotheriida are the second order of pill millipedes. In contrast to the northern pill millipedes, Sphaerotheriida are generally quite large ranging from 20-95mm in length. They have one additional segment as compared to Glomerida with 13 total segments and 21-23 pairs of legs. The males have two additional pairs of legs modified into anterior and posterior telopods as compared to the females. Like Glomerida, Sphaerotheriida are capable of volvation but unlike Glomerida where the tergites edges are hidden behind the enlarged second tergite, also called the thoracic shield, the tergite edges in Sphaerotheriida fit into a groove on thoracic shield and in some species they have special ledges that lock the tergites in the closed position to allow passive volvation. 

Sphaerotheriida do not have defensive glands and depend entirely on the passive defense of volvation to prevent predation

Reproduction: 

Reproduction is much the same as in Glomerida with the males using the telopods for clasping females during direct mating

Range:

They are found in southern Africa, Madagascar, southern India, southern Asia, Australia, and New Zealand.

Diet: 

As with Glomerida, Sphaerotheriida are detritivores and feed on decaying plant matter and most live in leaf little although some species appear to be arboreal.

Group members:

There are approximately 20 genera with more than 330 described species. There are no species found in the US

Description:

Slug millipedes are small, flattened millipedes and unlike other millipedes in the infraclass Pentazonia they lack the ability of volvation and lack eyes. Adult females have 21 segments for 36 pairs of legs. There are generally 35 walking legs plus a modified pair of sensory legs that extend over the anal plate and protrude posteriorly. Males are rare or absent in most species but when present have 20 segments with the final pair of legs modified into large telpods. There is some variability in the number of segments and legs however. Female also have enlarged ovipositors behind the second pair of legs.   

Several species are troglobiotic, while some members of the family Termitodesmidae are known to have commensal relationships with termites. 

This order appears to lack chemical defensive glands.

Reproduction:

When males are present, telopods are assumed to be used in mating similarly to the pill millipedes. Given the apparent lack of males in some species they may also reproduce via parthenogenesis. However, the order is extremely under studied, and so currently little is known

Range:

Found throughout central and south America as well as south Asia and parts of Oceania. 

Diet: 

Currently unknown. 

Group members:

There are currently 3 genera with approximately 30 described species. No species are found in the US 

Description:

Polyzoniida are small millipedes, generally 5-30mm in length. Their bodies are slightly domed dorsally with a flat ventral side. As adults they have >30 segments but generally less than 50 (although Eumillipes persephone discovered in 2021 has as many as 330 segments). The young are born with only 3 pair of walking legs. Their tergites are smooth and polished. Heads are much smaller than the width of the collum, triangular, with two dark eye spots with 3-4 ocelli per side. They lack a dorsal groove and true paranota. 

The order has bilateral single-chambered repugnitorial glands located on the lateral edge of the tergites. At least one species produces a chemical that smells similar to camphor, thus the common name.

Reproduction:

Polyzoniids have the 9th and 10th pairs of legs on the 7th and 8th body segment modified into gonopods. The gonopods  are used by the male during reproduction to transfer the spermatophore into the females gonopore (direct copulation) 

Range:

Polyzoniids have a nearly worldwide distribution and are found on all major continents other than antarctica.  

Diet:

As with other millipedes in the superorder Colobognatha, Polyzoniida exclusively feed on fungi. They utilize modified mouthparts for sucking.

Group members:

There are 3 families with 37 genera and approximately 140 described species currently. Only two families are native to the US, but all three are now found here

Description:

Platydesmids are small elongate millipedes measuring up to 60mm and having between 30 and 110 body segments in adults. Unlike polyzoniids, they have paranota (lateral projections) on their body segments. Most species also have tubercles on the surface of the tergites giving them a bumpy appearance. They have a thin dorsal groove. Their heads are generally more similar in size to the collum. They lack ocelli but have bulged projections above the antennae sockets. 

The order has bilateral single-chambered repugnitorial glands located on the lateral edge of the tergites. At least one species has been found to produce a unique alkaloid chemical defense that has been termed gosodesmine.

Reproduction:

As with polyzoniids, the males have the 9th and 10th pairs of legs on the 7th and 8th body segment modified into gonopods and reproduction is much the same. Uniquely within this group there are several species that exhibit paternal care, with the father wrapping around the eggs, keeping them safe and clean until they hatch 

Range:

Platydesmids are found mostly in forested areas and occur in a temperate band around the globe that includes areas of North and Central America, southern Europe, and Southern Asia up to Japan.  

Diet:

As with other millipedes in the superorder Colobognatha, platydesmids exclusively feed on fungi. They utilize modified mouthparts for sucking. 

Group members:

Two families with approximately 14 genera and 70 species currently described. A single family with around 12 species have been described in the US.  

Description:

The Siphonpcryptids share features with both of the previous orders of Colobognatha. They are shaped similarly to polyzoniids and have small triangular heads and dark ocelli. They may lack paranota as in polyzoniids or have slightly to well developed paranota/paraterga similar to platydesmids. They have rough tergites with two rows of  tubercles and a dorsal groove as in platydesmids. They are generally small and have 25-50 body segments. 

The millipedes appear quite rare, and little is known about them. They do possess ozopores and repugnitorial glands. 

Reproduction:

As with polyzoniids and platydesmids, the males have the 9th and 10th pairs of legs on the 7th and 8th body segment modified into gonopods and reproduction is much the same. 

Range:

They appear to have quite a unique range and are so far only known from the Canary islands, Malaysia, Sumatra, Taiwan, Hong Kong, and Nepal.

Diet:

As with other millipedes in the superorder Colobognatha, Siphonocryptida exclusively feed on fungi. They utilize modified mouthparts for sucking. 

Group members:

There is currently only a single described family with 6 known species. None occur in the US. 

Description:

Stemmiulida are small millipedes generally not exceeding 50mm in length with more that 32 segments (generally 39 to 60). The millipedes appear cylindrical but are somewhat laterally compressed such that they are taller than they are wide. Their bodies also taper caudally becoming gradually smaller towards the posterior segments. Stemmiulids have a dorsal groove that runs the length of the body. They have large, round heads with one or two ocelli. If two ocelli are present, one is noticeably larger than the other.

Some species have the ability to spring off the ground several inches when disturbed and so are sometimes referred to as jumping millipedes.

Stemmiulida have repugnatorial glands and have been reported to produce phenolic-based compounds. 

Reproduction:

In males the first pair of legs are enlarged and the anterior pair of legs on the 7th segment are modified into gonopods. The posterior pair of legs on the 7th segment are also reduced. Stemmiulida are the only millipedes other than platydesmids where parental care of eggs has been officially recorded (however some polydesmids have been observed possibly guarding eggs. 

Range:

Stemmiulids are found throughout Central America, tropical South America, and the Caribbean islands, as well as central Africa, southern India and Sri Lanka, and New Guinea

Diet:

The diet of stemmiulids is not clear from the current literature, but they have mouthparts similar to polydesmids and so are likely primary detritivores feeding in leaf litter.   

Group members:

Stemmiulida is comprised of a single family stemmiulidae with approximately 150 documented species. None occur in the US. 

Description:

Chordeumatida are small millipedes ranging from ~4-25mm in length. The number of body segments ranges from 26-32, but never exceeds 32. They have a 3+3 arrangement of setae on each segment, although they can be difficult to resolve in life. The setae are arranged in a row on either side of the tergites. The furthest lateral setae may be hidden under the adjacent tergite. All species have a dorsal groove, although it may not be apparent on smaller individuals. The body form is generally tapered caudally and paranota may be present or absent depending on the family. The collum is small giving the appearance of a neck and the head has large undivided basal mandibular lobes giving the appearance of large “cheeks”. They have a loose arrangement of many ocelli above the antennae.

The order appears to lack any chemical defensive glands.

Reproduction:

Males have leg pairs 8 and 9 modified into gonopods. Some species also have more extensive gonopodal complexes involving additional leg pairs including pair 7, 10, and 11. Gonopods are used for spermatophore transfer.

Range:

Nearly worldwide distribution missing only in sub-Saharan Africa and tropical areas of south America as well as Antarctica. 

Diet:

Chordeumatida are omnivorous detritivores feeding mainly on leaf litter and rotting wood. Several species have also been reported feed on dead insects, centipedes, snails, and worms. 

Group members:

Chordeumatida extremely speciose with more than 1200 described species split into approximately 50 families. There are 14 families and more than 50 species present in the US. 

Description:

Callipodida are moderately sized rounded millipedes reaching upwards of 100mm in length with 40-60 body segments. With the exception of a single genus (Callipodella) they are decorated with longitudinal ridges/crests running down the length of their bodies. All described species lack paranota and all have a dorsal groove. Their heads are large, rounded and lack a distinct labral suture line. Many ocelli are present and form a tight, triangular cluster above the antennae. 

When disturbed callipodids often excrete copious amounts of white liquid from their ozopores (see image). The liquid is a phenolic derivative and appears to be composed mainly of 4-methylphenol. 

Reproduction:

Males have the anterior leg pair on the 7th segment modified into a gonopod. The gonopod is normally concealed inside of a pocket unless they are actively breeding. The posterior leg pair on the 7th segment is a normal walking leg. 

Range:

Callipodida are primarily found in the southern regions of the northern hemisphere  and are present in North America, Europe, west Asia, southern China and south east Asia

Diet: 

Callipodida are omnivorous detritivores feeding mainly on leaf litter and rotting wood. Several species have also been reported feed on dead insects, centipedes, snails, and worms. Some may even be semi-carnivorous.   

Group members:

There are currently ~130 described species divided into 8 families. Two families occur in the US  

Description:

Polydesmids are small to moderately sized millipedes with 19-21 body segments (most with 20) ranging in size from 3-130mm. The body segments generally have paranotal, although paranota are absent in some species. Segments may be smooth or possess tubercles and/or setae. A dorsal groove is never present. In dissection, the somites do not possess any evidence of sutures. The collum is generally wider than the head and the head is large and rounded. All species are blind and do not possess eyes or ocelli. 

All species possess repugnatorial glands and ozopores. Polydesmids emit a variety of compounds, most notably many species in the group produce hydrogen cyanide. This factor has lead to the common name “cherry millipedes” for the xystodesmids. 

Reproduction:

Males have the anterior leg pair on the 7th segment modified into a gonopod. The posterior remains a normal walking leg. The gonopods are highly modified and used for species-level ID. Eggs are laid in nests in the soil. While not formally documented, females of some polydesmid species have been observed to guard eggs, in particular Pseudopolydesmus serratus  

Range:

Worldwide distribution, including pacific islands and even Iceland due to anthropogenic movement.  

Diet:

Polydesmids are detritivores and primarily feed on decaying plant matter. Most species are found in thick leaf litter/duff which compose their main diet. 

Group members:

Polydesmids are the most specious millipede order with nearly 6000 described species in 29 families. There are 10 families found in the US

Description:

Spirobolidans are robust, smooth, cylindrical millipedes with 30-60 body segments. They lack a dorsal groove, although may have a faint dorsal suture. They also lack paranota. The first five segments have only a single pair of legs each. They have a large collum and large round head. The order has a distinct labral suture that extends upwards from the mouthparts and is the key identification feature. Eyes with many ocelli form a tight roundish cluster above the antennae. Many species are very brightly colored with most having some level of reds or yellows. 

Spirobolidans possess repugnatorial glands and ozopores and can produce a variety of compounds. When disturbed many species produce large volumes of dark or yellow colored liquid containing benzoquinone that if touched stains skin and can cause mild chemical burns. 

Reproduction:

Both leg pairs on the 7th segment are modified into gonopods with the posterior gonopods used in sperm transfer and the anterior further modified and fused into a plate-like structure. Eggs are laid in leaf litter. 

Range:

Spirobolids are found throughout the western hemisphere including north, central, and south America as well as the Caribbean. They are also found in sub-Saharan Africa, across India, east Asia, Australia, and several pacific islands. 

Diet:

Spirobolids feed primarily on detritus and decaying plant matter as well as soft parts of some live plants.  

Group members:

There are nearly 500 described species of spirobolids split into 12 families. There are 6 families and 35 described species in the US including 2 introduced species.  

Description:

Spirostreptids are cylindrical millipedes and while generally large, can vary widely in size from ~6mm to greater than 300mm in length with 30-90 segments. Their segments are generally smooth, but can also be decorated with ridges or tubercles. The collum is generally large and the head large and round. Eyes are generally present but can vary greatly in the number of ocelli. Spirostreptida generally lack a dorsal groove, although it is present in some species. All species lack paranota. In males the first pair of legs is never modified unlike in Juida where the first pair of legs is often modified. The diagnostic feature for this order requires examination of the mouth parts. The side pieces of gnathochilarium are separated by a central plate, unlike Julida where the side pieces meet at the midline (see drawing). 

Spirostreptids possess repugnatorial glands and ozopores and can produce a variety of compounds. Several species have been reported to excrete their chemical defense with enough force to squirt fluid several inches. 

Reproduction:

In males, both pairs of legs on the 7th segment are modified into gonopods

Range:

Spirostreptida are primarily tropical and are found north and south America, Africa, Asia south of the Himalayas, and Australia. 

Diet:

Spirostreptida feed primarily on detritus and decaying plant matter as well as soft parts of some live plants. In captivity they will readily eat fruits and vegetables as well as dead insects and other protein sources such as fish food. 

Group members:

Spirostreptida is the third largest order of millipede with more than 1000 described species in 10 families. Three families occur in the US

Description:

Julida are the final order of cylindrical bodied millipedes. As with Spirobolida and Spirostreptida the overall body structure is snake-like and cylindrical. Julids tend to be smaller than the other two orders with species ranging in size from 10-120mm. Juida vary in the number of segments but all have more than 30. The collum is generally large and the head is large and round. Eyes are always present with most species having a large cluster of ocelli above the antennae. In fresh specimens, a whirl of setae is often present on the posterior margin of the segments. Dorsal groove and paranota are always absent. The diagnostic features require examination of head and mouthparts. Julida lack the labral suture found in spirobolida and the side pieces of gnathochilarium meet at the midline unlike in spirostreptida.

Julida possess repugnatorial glands and  ozopores and can produce a range of chemical defenses   

Reproduction:

Males of many species of Julids have their first leg pairs modified into small hooks or greatly enlarged into claspers used to hold females during reproduction. Both leg pairs on the 7th segment are modified into gonopods used for sperm transfer.  

Range:

Julids are primarily temperate and are found in North America south down to Panama, Europe, Asia north of the Himalayas, as well as parts of southeast Asia. 

Diet:

Primarily detritivores Julids will also eat soft parts of some live plants. In captivity they will readily eat fruits and vegetables as well as dead insects and other protein sources such as fish food.

Group members:

There are ~750 described species of Julid in 24 families. There are 9 families found in the US.  

Description:

Siphoniulida is a small and little-known order of millipedes that contains only 2 known species. The body is cylindrical and has been described as nematode-like. They have 51 segments but are very small at less than 7mm in total length. They lack a dorsal groove, paranota, and are eyeless. The collum is enlarged and the head is elongated into a beak-like structure.

Repugnatorial glands appear to be absent.  

Reproduction:

The anterior leg pair on the 7th segment is modified into a gonopod while the posterior leg pair is unmodified. 

Range:

Siphoniulus alba is only known from a single specimen collected in Sumatra, while Siphoniulus neotropicus is known from Guatemala and Mexico in Chiapas and Veracruz

Diet:

Unknown 

Group members:

2 species currently known. None are found in the US.