Taxonomic revision and Red List assessment of the ‘red millipede’ genus Centrobolus (Spirobolida: Pachybolidae) of South Africa.

Abstract

There are over 500 described species of millipedes in southern Africa, as well as a large number of species that have not been discovered or described. One group of poorly studied millipedes is the genus Centrobolus, for which 39 species were previously described. The species in this genus and specimens are difficult to identify based on the existing literature and identification keys. The genus distribution is also not well known, but it is thought that most species have narrow ranges and may be threatened by habitat loss and degradation. This study revises the taxonomy of Centrobolus, and provides detailed species descriptions, an identification key and illustrations of the main characters. The distribution of each species is updated. An assessment of the threat status of each species according to the IUCN Red List criteria is also carried out. The study used specimens deposited in Iziko and KwaZulu-Natal (Pietermaritzburg) Museums as well other material previously collected through field work. A total of 826 specimens were examined representing 28 Centrobolus species. Male gonopod structure, distribution of tarsal pads in male legs, colour pattern, female vulva structure and body sculpturing including scobinae were examined and illustrated. Where necessary, specimen localities were georeferenced and maps showing species’ distributions were produced. The IUCN Red List categories and criteria were used to assess the threat status of each Centrobolus species. Four possible new species have been identified; three of these are from KwaZulu-Natal, and the fourth is from the Eastern Cape. The two previously described subspecies are considered to be distinct species. The Red List assessment categorised most species as Data Deficient because of the poor knowledge of distribution, or Least Concern because the species are relatively widely distributed, or they are in less accessible and sparsely populated areas. Twelve species are considered threatened and this include nine Vulnerable and three Endangered species. Key areas for future research include additional surveys both to increase knowledge of distribution and habitat preferences, and to provide material for molecular studies.