Abstract
Surface structures have rarely been the subject of a comprehensive study in Polydesmida despite their tremendous variety within this order. A number of these peripheral structures are here studied in most families of the suborders Polydesmidea and Dalodesmidea (sensu Hoffman 1980), using scanning electron microscopy. An illustrated description of the surface sculpture of the prozonite, the limbus and the intercalary cuticular micro-scutes on the metazonite is given for the first time for the studied families, together with an account of some other poorly known surface structures. Taken together, these characters allow us to recognize two main groupings of families. The families Ammodesmidae, Cryptodesmidae, Cyrtodesmidae, Haplodesmidae, Oniscodesmidae and Pyrgodesmidae have knobs on the posterior part of the prozonites, a toothed to lobed limbus, and no micro-scutes on the metazonites, wheras the families Fuhrmannodesmidae, Polydesmidae, Dalodesmidae, Macrosternodesmidae, Nearctodesmidae, Opisotretidae and Trichopolydesmidae have no knobs on the posterior part of the prozonites, a spiky or reduced limbus, and intercalary micro-scutes on the metazonites. The results are complemented with literature records and compared with current taxonomic and phylogenetic interpretations of the group.