Spirobolida

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Spirobolida is an order of round-backed millipedes. It includes about 500 species in 12 families. They are arthropods in the class Diplopoda and belong to the group Juliformia. A key feature is a pronounced vertical suture on the front of the head. Most species live in tropical regions, and many are brightly colored. Adult males have two pairs of modified legs called gonopods for mating: the hind pair (the eighth and ninth legs) transfers sperm, while the front pair is fused into a plate. The order is divided into two suborders: Spirobolidea and Trigoniulidea. Synonyms used in the past include Anocheta and Haplogonophora.