Sphaeromimus andrahomana

Sphaeromias andrahomana is a critically endangered pill millipede endemic to the limestone karst regions of western Madagascar. This small arthropod, measuring approximately 8-12 millimeters when fully rolled into its characteristic defensive ball, displays a glossy dark brown to black exoskeleton with subtle segmentation patterns. The species belongs to the Arthrosphaeridae family, a group of millipedes renowned for their ability to completely enroll their bodies for protection.

Found exclusively in the Ankarafantsika region's dry deciduous forests, this millipede inhabits the leaf litter and soil layers of limestone outcrops, where it feeds on decomposing organic matter and plays a crucial role in nutrient cycling. The species demonstrates remarkable site fidelity, with individuals rarely venturing beyond their immediate microhabitat of fallen logs and rock crevices. Its distribution is severely fragmented across fewer than five known locations, each covering less than one square kilometer.

The IUCN Red List classifies Sphaeromias andrahomana as Critically Endangered due to its extremely restricted range and ongoing habitat degradation. Despite its precarious status, recent surveys have confirmed the species' persistence in protected areas within Ankarafantsika National Park, where forest restoration efforts are helping stabilize remaining populations. The species exhibits typical millipede reproductive behavior, with females depositing eggs in soil chambers during Madagascar's wet season, though reproductive rates appear lower than related species, possibly due to environmental stress.

This species inhabits the understory of dry deciduous forests growing on limestone substrates in western Madagascar, specifically within leaf litter accumulations and soil pockets between limestone rocks. The millipedes require consistently moist microhabitats with abundant decomposing organic matter, typically found in shaded areas beneath fallen logs and within rock crevices at elevations between 200-400 meters.