Suborder Trigoniulidea

Trigoniulidea is a suborder of millipedes within the order Spirobolida, belonging to the class Diplopoda in the phylum Arthropoda. Members of this group are part of the round-backed millipedes and are recognized for their cylindrical bodies and numerous segments bearing paired legs.

Millipedes in the suborder Trigoniulidea generally have elongated, smooth, and robust bodies with a rounded cross-section. Like other millipedes, most body segments possess two pairs of legs, which allow them to move slowly through soil and leaf litter. Their coloration is commonly brown, black, or reddish, though some species may display lighter bands or patterns.

Species of Trigoniulidea are mainly distributed in tropical and subtropical regions, particularly in Southeast Asia, Africa, and other humid environments. They typically inhabit forest floors, living in leaf litter, soil, and decaying wood where moisture levels are relatively high.

Ecologically, these millipedes function as detritivores, feeding on decomposing plant material such as fallen leaves, rotting wood, and organic debris. Through this feeding behavior, they contribute to the decomposition process and nutrient cycling within terrestrial ecosystems.

When threatened, many species in this suborder protect themselves by curling their bodies into a tight spiral and releasing defensive chemical secretions that help deter predators.

One of the principal families within this suborder is Trigoniulidae, which includes numerous species found primarily in tropical regions.