Phylogenetic analysis of the Australian trans-Bass Strait millipede genus Pogonosternum (Carl, 1912) (Diplopoda, Polydesmida, Paradoxosomatidae) indicates multiple glacial refugia in southeastern Australia

Abstract

This study documents the first detailed phylogenetic analysis of an Australian paradoxosomatid millipede genus. Two mitochondrial genes (partial COI and 16S) as well as partial nuclear 28S rDNA were amplified and sequenced for 41 individuals of the southeastern Australian genus Pogonosternum Jeekel, 1965. The analysis indicates that five species groups of Pogonosternum occur across New South Wales, Victoria and Tasmania: Pogonosternum nigrovirgatum (Carl, 1912), Pogonosternum adrianae Jeekel, 1982, Pogonosternum laetificum Jeekel, 1982 and two undescribed species. Pogonosternum coniferum (Jeekel, 1965) specimens cluster within Pogonosternum nigrovirgatum. Most of these five species groups exhibit a pattern of high intraspecific genetic variability and highly localized haplotypes, suggesting that they were confined to multiple Pleistocene refugia on the southeastern Australian mainland. The phylogenetic data also show that northwestern Tasmania was colonized by Pogonosternum nigrovirgatum, probably from central Victoria, and northeastern Tasmania by an as yet undescribed species from eastern Victoria.

Phylogenetic and morphological discord indicates introgressive hybridisation in two genera of Australian millipedes (Diplopoda, Polydesmida, Paradoxosomatidae)

“…Total genomic DNA was extracted using a Qiagen DNAeasy Blood & Tissue kit following the standard protocol with an incubation of tissue for 48h. Glom primer cocktail pairs (Decker 2016a, 2016b, Macek et al 2014) were used to sequence a 618 bp fragment of the mitochondrial cytochrome c oxidase subunit I (COI) gene. Primer pairs 28S D1a (Fw) and 28S D3b (Rv) (Dell’Ampio et al 2009) were used to amplify 1225 bp of the D2 fragment and adjacent areas of D1 and D3 on the nuclear 28S ribosomal RNA gene.…”

“…Primer pairs 16Sar (Fw) (5’-CGCCTGTTTAACAAAAACAT-3’) and 16Sbr (Rv) (5’-CCGGTCTGAACTCAGATCACGT-3’) (Simon et al 1994) were used to sequence a 566 bp fragment of the large-subunit ribosomal RNA (16S) gene. For PCR protocol and all primer sequences (COI, 16S, 28S) see Decker (2016a, 2016b). Fragments were sequenced in both directions by the BiK-F Laboratory Centre, Frankfurt, Germany.…”

“…Two cases of disagreement between relationships inferred from morphological similarity and molecular phylogenetics were observed in recent taxonomic studies of the Australian paradoxosomatid genera Pogonosternum Jeekel, 1965 (Decker 2016a, Decker et al 2017) and Somethus Chamberlin, 1920 (Decker 2016b). These two cases are described here in detail and discussed with regard to hybridisation, past introgressive hybridisation events and aberrant morphology.…”

Revision of the Australian millipede genus Pogonosternum Jeekel, 1965, with descriptions of two new species (Diplopoda, Polydesmida, Paradoxosomatidae)

“…A phylogenetic analysis (Decker 2016a) showed that this species is very closely related to P. laetificum with low genetic distances between populations of the two species.…”

“…10), sometimes both forms present within one population, with male brushes ranging to legpair 7, except in Brisbane Ranges National Park to legpair 9. Pogonosternum coniferum is here made a synonym of P. nigrovirgatum due to the existence of these intermediate forms and the fact that P. coniferum clusters with P. nigrovirgatum in a phylogenetic analysis based on mitochondrial COI and 16S rDNA sequences (Decker 2016a). …”