''Illacme plenipes'' is a siphonorhinid

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 ...

found in the central region of the

U.S. state In the United States, a state is a constituent political entity, of which there are 50. Bound together in a political union, each state holds governmental jurisdiction over a separate and defined geographic territory where it shares its sover ...

California California is a U.S. state, state in the Western United States, located along the West Coast of the United States, Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the List of states and territori ...

. It has up to 750 legs. One of two known species in the genus '' Illacme'', it was first seen in 1926, but was not rediscovered until 2005, almost 80 years after its discovery, by Paul Marek, then a Ph.D. student at

East Carolina University East Carolina University (ECU) is a public university, public research university in Greenville, North Carolina. It is the fourth largest university in North Carolina. Founded on March 8, 1907, as a Normal school, teacher training school, East ...

Description

On average, ''I. plenipes'' have over 600 legs, twice the average for millipede species, with one recorded specimen having 750 legs. It had the most legs of any species known until ''

Eumillipes persephone ''Eumillipes'' is a genus of millipede in the family Siphonotidae. It contains a single species, ''E. persephone'', known from the Eastern Goldfields of Western Australia. The species was first collected in 2020, discovered in three drill holes, ...

'' was described in 2021, which had 1306 legs. It is relatively small-bodied among millipedes. Females grow to just over 3 cm; males are slightly smaller and have fewer legs.

Taxonomic history

The species was first discovered in

San Benito County San Benito County (; ''San Benito'', Spanish for "St. Benedict"), officially the County of San Benito, is a county located in the Coast Range Mountains of the U.S. state of California. As of the 2020 census, the population was 64,209. The coun ...

, part of the

California Floristic Province The California Floristic Province (CFP) is a floristic province with a Mediterranean-type climate located on the Pacific Coast of North America with a distinctive flora similar to other regions with a winter rainfall and summer drought climate l ...

, in 1926 by federal scientist Orator Cook and formally described by Cook and

Harold F. Loomis Harold Frederick Loomis (December 23, 1896 – July 5, 1976) was an American botanist and myriapodologist known for his contributions to agronomy, plant pathology, and millipede taxonomy. He worked for the U.S. Department of Agriculture for over ...

in 1928. Cook and Loomis described the species without illustrations, and in 1996 Rowland Shelley of the

North Carolina Museum of Natural Sciences The North Carolina Museum of Natural Sciences (NCMNS) is the largest museum of its kind in the Southeastern United States. It is the oldest established museum in North Carolina, located in Raleigh. In 2013, it had about 1.2 million visitors, and i ...

re-examined specimens and redescribed the species. Marek and colleagues produced a more detailed description of the morphology of ''I. plenipes'' in 2012 and provided refined illustrations based on scanning electron micrography.

Classification

''Illacme'' is a member of the order

Siphonophorida Siphonophorida (Greek language, Greek for "tube bearer") is an order of millipedes containing two families and over 100 species. Description Millipedes in the order Siphonophorida are long and worm-like, reaching up to in length and up to 190 ...

and family

Siphonorhinidae Siphonorhinidae is a family of millipede in the order Siphonophorida. There are at least 4 genera and about 12 described species in Siphonorhinidae. Genera These four genera belong to the family Siphonorhinidae: * '' Illacme'' Cook & Loomis, 19 ...

. A second species of the genus, '' Illacme tobini'', was described in 2016. Based on a phylogenomic analysis of millipedes in the subterclass Colobognatha, the closest relative of ''Illacme'' is '' Nematozonium'' of South Africa which shares a long, narrow body shape and characteristics including

gonopods 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 milli ...

References

External links

National Public Radio News article on ''Illacme plenipes''

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BBC article on ''Illacme plenipes'' with film
{{Taxonbar, from=Q138813 Millipedes of North America Endemic fauna of California Animals described in 1928 Articles containing video clips Siphonophorida Fauna without expected TNC conservation status