Pentazonia is a taxonomic infraclass of millipedes containing the pill-millipedes (Oniscomorpha) which can roll into a ball and the order Glomeridesmida which cannot. Defining traits (apomorphies) include divided sternites, a labrum with single median tooth, and an enlarged pygidium on the hind-most body segment.[1] Pentazonia is in the dominant millipede subclass Chilognatha which have a calcified exoskeleton and modified sperm-transferring legs in males. In contrast to the Helminthomorpha – the other Chilognathan infraclass, the sperm-transferring legs are located on posterior body segments and known as telopods. Pentazonians are relatively short-bodied, with between 13 and 21 body segments.[2] The Pentazonia contains one extinct order, Amynilyspedida, often referred to the Oniscomorpha.[3]
^Hannibal, Joseph T; Feldmann, Rodney M. (1981). "Systematics and Functional Morphology of Oniscomorph Millipedes (Arthropoda: Diplopoda) from the Carboniferous of North America". Journal of Paleontology. 55 (4): 730–746.
