Spirobolida

Not to be confused with Spirostreptida.

Spirobolida is an order of "round-backed" millipedes containing approximately 500 species in 12 families.^[1] Its members are distinguished by the presence of a "pronounced suture that runs "vertically down the front of the head".^[2] Most of the species live in the tropics, and many are brightly coloured.^[2] Mature males have two pairs of modified legs, the gonopods, consisting of the 8th and 9th leg pair: the posterior gonopods are used in sperm-transfer while the anterior gonopods are fused into a single plate-like structure.^[3]

Front and rear views of the anterior (A, B) and posterior left (C, D) gonopods of a spirobolidan

Spirobolida
Narceus americanus
Scientific classification
Kingdom:	Animalia
Phylum:	Arthropoda
Subphylum:	Myriapoda
Class:	Diplopoda
Superorder:	Juliformia
Order:	Spirobolida Bollman, 1893
Families
12: See text
Synonyms
Anocheta Cook, 1895 Haplogonophora Brolemann, 1931

The families are divided into two suborders:^[1]

Suborder Spirobolidea

• Allopocockiidae
• Atopetholidae
• Floridobolidae
• Hoffmanobolidae
• Messicobolidae
• Pseudospirobolellidae
• Rhinocricidae
• Spirobolellidae
• Spirobolidae
• Typhlobolellidae

Suborder Trigoniulidea

• Pachybolidae
• Trigoniulidae

Select species

• Narceus americanus, a commonly seen species in eastern North America
• Crurifarcimen vagans, the "wandering leg sausage"
• Anadenobolus monilicornis, the yellow-banded millipede
• Eucarlia, a genus of threatened Indo-Pacific millipedes