Millipeds of the eastern Piedmont region of North Carolina, U.S.A. (Diplopoda)

Abstract

Summary The diplopod species of the eastern Piedmont counties of North Carolina have been surveyed in order to update earlier records from the Triangle (Raleigh-Durham-Chapel Hill) region. The following taxa are reported from the state for the initial time: two families—Andrognathidae and Trichopolydesmidae; five genera—Andrognathus, Cylindroiulus, Ophyiulus, Chaetaspis, and Auturus; and six species—five corresponding to these genera plus Pseudopolydesmus collinus. Likewise, the family Branneriidae and Cleidogona major, Branneria carinata, Narceus annularis, Abacion magnum, and Pseudopolydesmus branneri are recorded from the Piedmont for the first time. The occurrence of Pleuroloma is also reported, although it has previously been listed as Zinaria, now considered a junior synonym. Cleidogona caroliniana and Pseudopolydesmus paludicolus are mentioned as potential Piedmont species, and a list of deleted records is presented. The results of this survey reveal an indigenous fauna of nine orders, 16 families, 23 genera, and 29 species, with a species/genus ratio (s/g) of 1·26. The total fauna, including introduced millipeds, consists of nine orders, 19 families, 29 genera, and 35 species, s/g = 1·21. The region of study is broken down by habitat into three subregions. The central subregion, with rolling hills and extensive deciduous forests, contains the most diverse fauna; the northeastern and southern subregions, consisting largely of pine habitats, have comparatively sparse faunas. Most species occur in predominantly hardwood forests, but Polyxenus fasciculatus, Andrognathus corticarius, Nopoiulus minutus, Uroblaniulus carolinensis, Branneria carinata, Abacion magnum, and Oxidus gracilis were found consistently in predominantly pine habitats as well. Some millipeds are common and range throughout the eastern Piedmont; others occur sporadically and are more restricted in their distributions. Pseudopolydesmus branneri, a common montane species, is unique to the southern area. Introduced millipeds, except Nopoiulus minutus, are found primarily in urban environments. The Deep-Cape Fear Rivers traverse the eastern Piedmont in a roughly east-west direction. Seventeen millipeds were collected primarily on only one side of this divide, but the disparity is considered significant for only three species. Andrognathus corticarius, common south of the rivers, has been collected north from only two localities despite intensive efforts to find it. The nominate subspecies of Sigmoria latior is restricted to the northern side, whereas intergrade specimens with S. l. hoffmani occur south. Apheloria tigana, the dominant eastern Piedmont xystodesmid, occurs in two colour patterns with a disparity around the rivers. On the southern side, the majority of individuals (91·3%) have middorsal spots running the entire length of the dorsum, whereas the majority north (64·9%) have spots on only the posterior-most segments. The importance of the Deep-Cape Fear Rivers as a distributional boundary is noted. A key to the milliped genera and species and pertinent diagnostic drawings are presented to aid in identification.