Worldwide distribution of cave-dwelling Chelodesmidae (Diplopoda, Polydesmida)

Chelodesmidae is one of the most species rich families within the Myriapoda. However, little is known regarding their association with caves. We provide a list of all Chelodesmidae taxa reported from caves, map their worldwide distribution, and discuss the troglomorphic features of the group. A total of 25 species and subspecies from 20 genera and 2 subfamilies have been recorded from 59 caves and cave systems in 11 countries. These numbers represent a surprisingly modest proportion (~3%) of the approximately 800 described species in the family. Records of cave-dwelling chelodesmids appear to be geographically biased with most taxa reported from the Neotropics, likely due to the greater diversity of the group in the region. The lack of published records from the Afrotropics can undoubtedly be attributed to low sampling efforts. In addition, many studies focusing on cave invertebrates, especially in the tropics, often fail to identify chelodesmid taxa to the species level, thus precluding their inclusion on checklists. The majority of the Chelodesmidae reported from caves do not display obvious adaptations to a subterranean lifestyle and are not troglomorphic. The five troglobitic taxa indicated in this study may represent relictual lineages suggesting that few, if any, radiations of chelodesmids within caves have occurred in the past. Increased efforts are needed to bridge the gap between our current understanding and the true diversity of the group in these fragile and threatened habitats, which is necessary to allow policy makers to prioritize appropriate and effective conservation efforts, including the protection of environments severely impacted by human activities.