Xystodesmidae

This family possess 57 genera in 4 sub-families primarily distributed in North America and Asia. It is often considered as representative of the Polydesmida as a whole amongst enthusiasts. The bright coloration and large size of many species has led to at least six genera and upwards of ten species entering culture, usually with limited to no success.

Paul Marek, Jackson Means, and Derek Hennen (2018) point out that, with how common mimicry is amongst xystodesmids even in the same geographical area, combined with the great variety of color morphs may may exist within a single species, identification of most Xystodesmidae based solely on color should be taken with a grain of salt.
An example of this phenomenon is the case of Apheloria polychroma and Brachoria sheari, two American species that can be found sympatrically in a part of Virginia. Both species have two morphs in the area, each of which mimic one of the morphs of the other species to a remarkable degree (Marek et al. 2018).

Note regarding the care of many Xystodesmidae in captivity

Despite the Xystodesmidae being very well represented in North America, both in the wild and in culturing attempts, enthusiasts there have largely failed in rearing multiple generations of any of the common genera. Specimens usually perish within a few months of captive life without producing offspring or molting.
It has been speculated that these results have something to do with temperature requirements not being adequately met in captivity, though continued attempts that experiment with these factors have still been unsuccessful insofar.
Research conducted by The MED team shows that as early as the 1940s researchers were able to raise Apheloria virginiensis corrugata successfully through several molts in petri dishes at temperatures prior believed to be deadly for the genus (24-27°C/75-80°F) on peat and mull substrates over the course of several months. While this is a far cry from multi-generational captive breeding, it does suggest that temperature may play less of a role in culturing Apheloria and perhaps other large-bodied xystodesmids, and the particular substrate (which is neither the assumed rotting wood base used for most polydesmids nor the standard round millipede substrate) may play more of a role than was originally thought.
Orin McMonigle reports in his work Millipeds in Captivity that Sigmoria die from the heat of a closed hand, so in any case further research and experimentation is needed.

~Connor Smotzer and Arthroverts (9/24/2021)

Page image (Xystodesmidae sp. from eastern USA) compliments of Arthroverts

Marek, P. E., Means, C. J., & Hennen, D. A.(2018). Apheloria polychroma, a new species of millipede form the Cumberland Mountains (Polydesmida: Xystodesmidae). Zootaxa, 4375 (3), 409-425. https://doi.org/10.11646/zootaxa.4375.3.7