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

Peter Decker

doi:10.3897/zookeys.578.8052

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.

Highlights

Pogonosternum Jeekel, 1965 is the most widespread and species-rich genus of the millipede tribe Antichiropodini Brölemann, 1916 in Victoria, with the five described species Pogonosternum nigrovirgatum (Carl, 1902), P. coniferum Jeekel, 1965, P. adrianae Jeekel, 1982, P. laetificum Jeekel, 1982 and the subspecies P. nigrovirgatum infuscum Jeekel, 1982, all hitherto recorded from Victoria only
Jeekel (1982) and Mesibov and Churchill (2003) have recorded undescribed Pogonosternum species from Tasmania, and Car (2010) listed two undescribed Pogonosternum species from New South Wales. Pogonosternum occurs on both sides of Bass Strait, which separates mainland Australia from Tasmania
The australiosomatine genus Somethus in South Australia was found to have high morphological and genetic variability within species was discovered: it seems probable that isolation in multiple glacial refugia during the Pleistocene was the evolutionary driving force for this variability (Decker 2016)

Summary

Introduction

Pogonosternum Jeekel, 1965 is the most widespread and species-rich genus of the millipede tribe Antichiropodini Brölemann, 1916 in Victoria, with the five described species Pogonosternum nigrovirgatum (Carl, 1902), P. coniferum Jeekel, 1965, P. adrianae Jeekel, 1982, P. laetificum Jeekel, 1982 and the subspecies P. nigrovirgatum infuscum Jeekel, 1982, all hitherto recorded from Victoria only. Phylogenetic studies of southeastern Australian soil invertebrates can give important insights into the impact of glacial periods during the Pleistocene (Byrne 2008, Endo et al 2014, Garrick et al 2004, Schultz et al 2009, Sunnucks et al 2006) and assist in identifying biogeographic barriers (Chapple et al 2011). For the australiosomatine species Orocladosoma kosciuskovagum (Brölemann, 1913) from the Australian Alps a hypothesis of multiple glacial refugia has been proposed (Endo et al 2014) to explain the results of such studies. The australiosomatine genus Somethus in South Australia was found to have high morphological and genetic variability within species was discovered: it seems probable that isolation in multiple glacial refugia during the Pleistocene was the evolutionary driving force for this variability (Decker 2016)

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Conclusion