Cyanide-defense
Guides
Apheloria virginiensis
Virginia cherry millipede, black-and-gold flat millipede, yellow and black flat millipede
Apheloria virginiensis is a large flat-backed millipede in the family Xystodesmidae, notable as the first myriapod described from North America in 1770. Adults range from 27–59 mm in length and exhibit striking aposematic coloration, typically black with yellow, pink, or orange spots on the paranota. This species secretes hydrogen cyanide and benzaldehyde as a chemical defense, producing a characteristic cherry or almond odor. It inhabits mesic deciduous and mixed forests in the piedmont and coastal plain regions of Virginia and North Carolina, where it contributes to leaf litter decomposition.
Boraria
Boraria is a genus of flat-backed millipedes in the family Xystodesmidae, established by Chamberlin in 1943. The genus is characterized by the lateral expansion of dorsal segments into paranota, giving individuals a flattened appearance distinct from cylindrical millipedes. Species in this genus, like other xystodesmids, produce hydrogen cyanide as a chemical defense and display bright aposematic coloration—typically black with yellow or orange markings—as warning signals to predators. The genus is part of the diverse Polydesmida order, which represents the culmination of diplosegmentation in millipedes with no external evidence of sutures between fused body somites.
Polydesmida
Flat-backed Millipedes
Polydesmida is the largest order of millipedes, containing over 5,000 described species. Members are commonly known as flat-backed millipedes due to the presence of lateral keels (paranota) on most body segments. This order includes all millipedes known to produce hydrogen cyanide (HCN) as a chemical defense. Polydesmids are found on every continent except Antarctica and exhibit the highest morphological diversity among millipede orders. They are characterized by a unique developmental mode called teloanamorphosis, in which adults reach a fixed number of segments and cease molting.
Xystocheir
Xystocheir is a genus of flat-backed millipedes in the family Xystodesmidae, endemic to California. The genus comprises nine species distributed in the Coast Ranges and Sierra Nevada. Members of this genus are notable for producing cyanide as a chemical defense against predators. Xystocheir dissecta, a species within this genus, has been documented to fluoresce under ultraviolet light.
Xystocheir brachymacris
Xystocheir brachymacris is a species of flat-backed millipede in the family Xystodesmidae, native to North America. Like other members of its family, it possesses chemical defense glands capable of producing hydrogen cyanide gas when disturbed. The species was described by Shelley in 1996.
Xystocheir dissecta
Xystocheir dissecta is a flat-backed millipede in the family Xystodesmidae. It is found along the coast of Northern California, particularly in and around the San Francisco Bay Area. The species is notable for its chemical defense system, producing hydrogen cyanide gas when threatened. Three subspecies are recognized: X. d. dissecta, X. d. microrama, and X. d. taibona.