Polyzoniida

Distinguished from other millipede orders by combination of: domed dorsal profile with flat venter; small cone-shaped head with reduced ocelli; absence of dorsal groove and paranota; thick antennae; highly variable segment number (20–88) within and between species. The camphor-like odor of defensive secretions is a notable field characteristic. Male gonopods on leg pairs 9 and 10 (rather than 8 and 9 as in some other groups) and their specific podomere configurations aid in family-level and species-level identification.

Small to medium-sized millipedes with a distinctly domed dorsal surface and flat ventral side. Body length ranges from 4–50 mm, most commonly 10–15 mm. Small, cone-like head with few ocelli. Antennae relatively thick. Body lacks dorsal groove and paranota (lateral segment extensions). Coloration frequently yellowish or pink, sometimes with characteristic black bands. Legs have six segments. Segment number highly variable, ranging from 20–88 segments even within the same species.

Worldwide distribution with family-level geographic partitioning. Hirudisomatidae: Spain to Himalayas in Eurasia, Japan, and North America from southwest Canada to central Mexico. Polyzoniidae: holarctic distribution in northwest and northeast United States, eastern Canada, and Europe from United Kingdom and France to Siberia. Siphonotidae: southern distribution in Brazil, Chile, South Africa, Southeast Asia, Indonesia, Tasmania, and New Zealand. In Africa, the order occurs only in South Africa and Madagascar. Notable disjunct distributions include Canary Islands and Madeira for some taxa.

Juveniles hatch with four leg pairs. Females protect their eggs.

Defensive secretions serve as a chemical resource for poison frogs (Dendrobatidae) in South America and Madagascar, which sequester these compounds for their own toxicity.

• Other Colobognatha orders (Platydesmida, Siphonocryptida)Share subterclass Colobognatha but differ in gonopod structure, segment number stability, and distribution patterns. Platydesmida and Siphonocryptida have more consistent segment numbers and different male reproductive appendage morphology.
• PolydesmidaBoth have flattened bodies, but Polydesmida possess paranota (lateral segment extensions) which Polyzoniida lack; Polydesmida also have a distinct dorsal groove.

• millipede
• camphor millipede
• Colobognatha
• chemical defense
• myriapod
• diplopod
• poison frog toxin source
• variable segmentation

• BugGuide
• Wikipedia
• GBIF taxonomy match
• NCBI Taxonomy
• Catalogue of Life
• A revision of the Siphonocryptidae (Diplopoda, Polyzoniida)
• Colobognatha millipedes in the Caucasus (Diplopoda: Polyzoniida, Platydesmida, Siphonocryptida)
• Octoglena claraqua, n. sp. (Polyzoniida: Hirudisomatidae), a new milliped from Idaho, USA; first record of the order from the western interior of North America