An ancient Antarctic endemic genus restored: morphological and molecular support for Gomphiocephalus hodgsoni (Collembola: Hypogastruridae)

摘要

Gomphiocephalus hodgsoni Carpenter was only the second collembolon dagger to be described from the Antarctic continent. It was collected first in 1902 from Granite Harbour, southern Victoria Land, Eastern Antarctica, by the British National Antarctic Expedition (1901-1904). Since then several studies have investigated the distribution, ecology, ecophysiology and molecular composition of the species. Despite two morphological redescriptions and an absence of detailed evolutionary phylogenetic studies, the genus Gomphiocephalus was recently reduced to a subgenus of Schoettella Schaffer. Here, we redescribe the species in detail and use morphological and molecular (cytochrome c oxidase subunit I and 28S) data to indicate its generic relationships within Hypogastruridae. Characters of Gomphiocephalus do not conform with those of any extant genus in the family, including Schoettella. In addition, the only Schoettella species described from the southern hemisphere, Schoettella subcorta Salmon, is shown here to belong in the genus Xenylla. Furthermore, molecular data indicates the genus has no close relationship to any other in Poduromorpha, and in particular Hypogastruridae. Therefore, we restore Gomphiocephalus to generic status. Our results reinforce the already recognized high level of endemism in the Antarctic fauna at both species and generic levels, and emphasise the necessity of using both morphological and molecular data in determining the systematics and evolutionary relationships of the fauna.