Juliformia is a taxonomic superorder of

millipede Millipedes are a group of arthropods that are characterised by having two pairs of jointed legs on most body segments; they are known scientifically as the class Diplopoda, the name derived from this feature. Each double-legged segment is a resu ...

s containing three living orders:

Julida Julida is an order (biology), order of millipedes. Members are mostly small and cylindrical, typically ranging from in length. Eyes may be present or absent, and in mature males of many species, the first pair of legs is modified into hook-like ...

, Spirobolida, and

Spirostreptida Spirostreptida is an order (biology), order of long, cylindrical millipedes. There are approximately 1000 described species, making Spirostreptida the third largest order of millipedes after Polydesmida and Chordeumatida. Description Spirostrept ...

, and the extinct group

Xyloiuloidea Xyloiuloidea is an extinct superfamily of millipedes that existed from the Lower Devonian through the Upper Pennsylvanian period in Europe and North America. Description Xyloiuloids are more or less cylindrical, with sternites, pleurites, and ...

known only from fossils.

Morphology

The species possess long cylindrical bodies with

sclerite A sclerite (Greek , ', meaning "hard") is a hardened body part. In various branches of biology the term is applied to various structures, but not as a rule to vertebrate anatomical features such as bones and teeth. Instead it refers most commonly ...

s (skeletal plates consisting of ventral sternites, lateral

pleurite A sclerite (Greek , ', meaning " hard") is a hardened body part. In various branches of biology the term is applied to various structures, but not as a rule to vertebrate anatomical features such as bones and teeth. Instead it refers most commonly ...

s, and dorsal

tergite A ''tergum'' (Latin for "the back"; plural ''terga'', associated adjective tergal) is the dorsal ('upper') portion of an arthropod segment other than the head. The anterior edge is called the 'base' and posterior edge is called the 'apex' or 'mar ...

s) fused into complete rings. Juliform millipedes possess defensive repugnatorial glands on all body segments except the last few, and are the only known millipedes to produce

quinones The quinones are a class of organic compounds that are formally "derived from aromatic compounds uch as benzene or naphthalene">benzene.html" ;"title="uch as benzene">uch as benzene or naphthalene] by conversion of an even number of –CH= group ...

in their defensive secretions. Juliform males have two pairs of

gonopod Gonopods are specialized appendages of various arthropods used in reproduction or egg-laying. In males, they facilitate the transfer of sperm from male to female during mating, and thus are a type of intromittent organ. In crustaceans and millip ...

s consisting of the modified 8th and 9th pair of legs: in Julida and Spirobolida the posterior gonopods (9th leg pair) are primarily involved in sperm-transferring, while in Spirostreptida it is the anterior gonopods (8th leg pair). Juliformians also lack Tömösváry organs and have a large collum (first body segment) which overhangs the rear of the head.

Taxonomy

The

is an extinct superfamily of fossil millipedes of uncertain placement within the Juliformia. Known from the

Lower Devonian The Early Devonian is the first of three epochs comprising the Devonian period, corresponding to the Lower Devonian series. It lasted from and began with the Lochkovian Stage , which was followed by the Pragian from and then by the Emsian, w ...

to the Upper Pennsylvanian, Xyloiuloidea consists of four families and several genera. The group was formerly considered a suborder of Spirobolida, but newly discovered species in 2006 required a reconsideration of classification, and the order to which Xyloiuloidea belongs remains undetermined.

References

Millipede taxonomy Arthropod superorders {{myriapoda-stub