Entomologists from the United States and Germany have described seven new species of giant pill-millipedes belonging to the Malagasy genus Sphaeromimus.
Sphaeromimus lavasoa (top right), Sphaeromimus andrahomana (bottom right) and color morphs of the previously known species Sphaeromimus musicus (left). Image credit: Wesener T et al.
The giant pill-millipede genus Sphaeromimus, which is Latin for small ball animal, was first described by scientists Henri Louis Frédéric de Saussure and Leo Zehntner in 1902, but until 2005 was known only from a single male specimen.
Sphaeromimus pill-millipedes live in the rainforests of southeastern Madagascar. They can roll up into a ball for protection. The size of this ball is typically equal to that of a ping-pong ball.
Males have a structure on their anterior telopod, known as the harp, which has several ribs and is able to produce sounds. This stridulation organ is still not well understood, but may play a role during courtship.
The discovery of the seven new species – Sphaeromimus titanus, S. vatovavy, S. lavasoa, S. andohahela, S. ivohibe, S. saintelucei, and S. andrahomana – is particularly exciting as some of them are microendemics, meaning they are only found in one tiny forest fragment, a few hundred meters long and wide.
While all previously known Sphaeromimus species show a normal size of 18–35 mm, one of the new species shows gigantism.
Another new species, Sphaeromimus andrahomana, offers clues to Madagascar’s ecosystems thousands of years ago.
Although the species was found in a cave in Madagascar’s southern dry spiny forest region, genetically, it is a rainforest taxon. The lemur skeletons found inside the same cave are also evidence that a rainforest existed in the now desert-like area until 3,000-5,000 years ago. The species, sheltered by the humid cave, is probably a living witness to this ancient rainforest.
Sphaeromimus lavasoa is restricted to the Lavasoa Mountain, which is covered by an isolated, slightly larger than 100 hectare, rainforest remnant, which is famous for the recent discovery of a large scorpion as well as a dwarf lemur species.
Sphaeromimus saintelucei is probably the most endangered millipede on Madagascar. It was found in a fragment of the Sainte Luce littoral rainforest characterized by its laterite soil that is now so small that no lemur or other large vertebrate species can survive in it.
The nearby Sainte Luce forest fragment with sandy ground harbors a different species, Sphaeromimus splendidus, also believed to be a microendemic.
“Despite their close proximity, both species are not even closely related. Both the fragments where they were found are currently threatened by a huge, billion-dollar titanium ore strip mining project,” commented Dr Thomas Wesener of the Research Museum Alexander Koenig in Bonn, Germany, the first author of a paper published in the journal ZooKeys.
“Although there are intentions to designate and manage conservation zones, the plan is to protect only one large fragment may result in the extinction of some of the species if additional conservation measures aren’t undertaken.”
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Wesener T et al. 2014. Integrative revision of the giant pill-millipede genus Sphaeromimus from Madagascar, with the description of seven new species (Diplopoda, Sphaerotheriida, Arthrosphaeridae). ZooKeys 414: 67–107; doi: 10.3897/zookeys.414.7730
