Polydesmida


Polydesmida is the largest order of millipedes, containing approximately 3,500 species, including all the millipedes reported to produce hydrogen cyanide.

Description

Members of the order Polydesmida are also known as "flat-backed millipedes", because on most species, each body segment has wide lateral keels known as paranota. These keels are produced by the posterior half of each body ring behind the collum. Polydesmids have no eyes, and vary in length from. Including the telson, adults have 19 or 20 rings, while juveniles may have from 7 to 19 rings. Mature males have a single pair of gonopods consisting of the modified forward leg pair of the 7th segment. Many of the larger species show bright coloration patterns which warn predators of their toxic secretions.

Ecology

Polydesmids are very common in leaf litter, where they burrow by levering with the anterior end of the body.

Classification

The c. 3500 species of Polydesmida are variously classified into four suborders, and 29 families, the largest including Paradoxosomatidae, Xystodesmidae, and Chelodesmidae.
;Dalodesmidea Hoffman, 1980. 2 families
;Leptodesmidea Brölemann, 1916. 13 families:
;Paradoxosomatidea Daday, 1889. 1 family
;Polydesmidea Pocock, 1887. 12 families