Reductoniscus costulatus

About Reductoniscus costulatus

Reductoniscus costulatus is a tiny terrestrial pill woodlouse in Armadillidae, reaching about 2 mm. Taiti and Howarth (1996, printed p. 67) report one Kauaʻi specimen collected from beach leaf litter at Hāʻena near the start of the Kalalau–Nā Pali Trail on 19 January 1973. Their survey identifies it as a new island record and describes the species as occurring in coastal low-altitude leaf litter and under stones elsewhere; its island checklist assigns adventive status. The single specimen demonstrates a historical occurrence in that precise microhabitat, rather than present-day abundance, a sustained colony, or an island-wide distribution. A specialist identification account describes broad rounded tubercles over the head and body, an hourglass-shaped telson, short truncated uropods and an ability to roll into a sphere. These traits inform the Atlas ecological reconstruction, which is separate from an existing CC0 microscope photograph taken in Florida. The photograph does not serve as Kauaʻi locality evidence, and external appearance in a small photograph cannot alone verify every microscopic identification character. No sex differences, juvenile stages, or current Kauaʻi trend are inferred from the old collection.