''Sinocallipus '' is a

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

of predominantly cave-dwelling

millipede Millipedes (originating from the Latin , "thousand", and , "foot") 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 derive ...

s in the

order Order, ORDER or Orders may refer to: * A socio-political or established or existing order, e.g. World order, Ancien Regime, Pax Britannica * Categorization, the process in which ideas and objects are recognized, differentiated, and understood ...

Callipodida. Five of the six known species are found in limestone caves on the Indochinese Peninsula from Vietnam to southern China, and it is the only callipodidan genus entirely confined to the

tropics The tropics are the regions of Earth surrounding the equator, where the sun may shine directly overhead. This contrasts with the temperate or polar regions of Earth, where the Sun can never be directly overhead. This is because of Earth's ax ...

. Individuals range from long and possess 55 to 70 segments. ''Sinocallipus'' is the sole taxon of the callipodidan suborder Sinocallipodidea, and thought to be the most primitive and

sister group In phylogenetics, a sister group or sister taxon, also called an adelphotaxon, comprises the closest relative(s) of another given unit in an evolutionary tree. Definition The expression is most easily illustrated by a cladogram: Taxon A and ...

to all other callipodidans. In contrast to many other millipede groups, the

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 millipe ...

s (reproductive legs) of ''Sinocallipus'' show little variation between species, while other characters such as color, size, and other body parts differ more noticeably between species.

Species

All species except ''S. thai'' have been collected solely from caves, and show

troglomorphic Troglomorphism is the morphological adaptation of an animal to living in the constant darkness of caves, characterised by features such as loss of pigment, reduced eyesight or blindness, and frequently with attenuated bodies or appendages. The ter ...

(cave-adapted) traits such as pale coloration, long antennae, and long legs. ''S. jaegeri'' and ''S. simplipodicus'' show reduced eyes, consisting of only 10 to 16 colorless

ocelli A simple eye or ocellus (sometimes called a pigment pit) is a form of eye or an optical arrangement which has a single lens without the sort of elaborate retina that occurs in most vertebrates. These eyes are called "simple" to distinguish the ...

each, while the other species have 33 to 50 black ocelli. ''S. thai'' is unique for its dark coloration and terrestrial habitat, and correspondingly has the most ocelli and shortest antennae.

References

External links

* Millipede genera Cave millipedes Millipedes of Asia Callipodida {{Millipede-stub

Species

See also

References

External links