Abstract
The species-rich giant pill-millipedes (Sphaerotheriida) often represent a microendemic component of Madagascar’s mega-invertebrate fauna. Of the chirping genus Sphaeromimus de Saussure & Zehntner, 1902, ten species have been described. Here, we describe two new species of Sphaeromimus integratively, combining light microscopy, scanning electron microscopy, DNA barcoding and micro-CT technology for the first time in a taxonomic description of a giant pill-millipede. S. kalambatritra sp. nov. and S. midongy sp. nov. are the first giant pill-millipedes collected and described from the mountainous rainforests of Kalambatritra and Midongy. Both species show island gigantism compared to their congeners. Our analysis of the mitochondrial COI gene shows that the two species are related to one another with a moderate genetic distance (9.4%), while they are more closely related to an undetermined specimen from the forest of Vevembe (6.3% and 8.4%). They stand in a basal position with S. ivohibe Wesener, 2014 and S. musicus (de Saussure & Zehntner, 1897). The four aforementioned species share a high number of stridulation ribs on the male harp. Our micro-CT analysis provides a look into the head of S. kalambatritra sp. nov. and shows that non-destructive CT methods are a useful tool for studying the inner morphology of giant pill-millipedes.
Highlights
Madagascar, the world’s 4th largest island, lies in the Indian Ocean east of Africa and has a tropical climate (Moat & Smith 2007)
The head of the female paratype of S. kalambatritra sp. nov. was dehydrated via an ascending ethanol series (96%, 100%) and critical point dried
Updated distribution of Sphaeromimus Including the two newly described species, the genus Sphaeromimus is still restricted to southeastern Madagascar
Summary
Madagascar, the world’s 4th largest island, lies in the Indian Ocean east of Africa and has a tropical climate (Moat & Smith 2007). Madagascar is considered one of the world’s hottest biodiversity hotspots (Myers et al 2000; Ganzhorn et al 2001) and provides shelter to a high. This high degree of endemism is probably due to its early isolation from Africa more than 150 Ma years ago and from India more than 80 Ma years ago (Wells 2003). A key thread to Madagascar’s biodiversity is the fast rate of deforestation of habitat (Harper et al 2007). From 1950 to 2000 the area covered by forests decreased by 40% (Green & Sussman 1990)
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