Mecistocephalus porosus is a species of soil centipede in the Mecistocephalidae family. This species is found in Fiji. This centipede can reach 41 mm in length.
This centipede was first described in 1887 by German entomologist Erich Haase. He based the original description of this centipede on a holotype found on the island of Viti Levu in Fiji. This species is known only from Fiji.
Haase originally described this centipede as a subspecies of M. tahitiensis. In 1920, the American biologist Ralph V. Chamberlin deemed M. tahitiensis porosus to be a junior synonym of M. tahitiensis. Since then, other authorities have adopted the synonymy proposed by Chamberlin. Despite this proposed synonymy and the original description of this centipede as a subspecies, many references list M. porosus as a separate species.
This centipede can reach 41 mm in length and reaches a maximum width of 2 mm in the middle of its body. The anterior segments are 1.8 mm wide, and the posterior segments are only 0.8 mm wide. This centipede features white spots on the tergites.