''Paeromopus'' 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 large cylindrical

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 endemic to the U.S. state of

California California () is a U.S. state, state in the Western United States that lies on the West Coast of the United States, Pacific Coast. It borders Oregon to the north, Nevada and Arizona to the east, and shares Mexico–United States border, an ...

. All species exceed 10 centimeters (4 inches) in length, and the largest, '' P. paniculus, ''reaching 16.5 cm (6.5 inches) is the longest millipede species in North America. The genus was named by German entomologist

Ferdinand Karsch Ferdinand Anton Franz Karsch (2 September 1853, in Münster – 20 December 1936, in Berlin) was a German arachnologist, entomologist and anthropologist. He also wrote on human and animal sexual diversity with his mother's maiden name included a ...

in 1881 and contains four species: three occupying small ranges in the

Sierra Nevada The Sierra Nevada ( ) is a mountain range in the Western United States, between the Central Valley of California and the Great Basin. The vast majority of the range lies in the state of California, although the Carson Range spur lies primari ...

mountains and one occupying a large range including the Sierra Nevada and much of

Northern California Northern California (commonly shortened to NorCal) is a geocultural region that comprises the northern portion of the U.S. state of California, spanning the northernmost 48 of the state's List of counties in California, 58 counties. Northern Ca ...

to the Central Coast.

Description

''Paeromopus ''millipedes are long and cylindrical, measuring in length and up to 8 mm (0.3 in) wide, with 68 to 80 body segments. The body color in most is brown to black with bands of light brown or yellow, although some individuals are dark gray or bluish gray with indistinct bands. The

legs A leg is a weight-bearing and locomotive anatomical structure, usually having a columnar shape. During locomotion, legs function as "extensible struts". The combination of movements at all joints can be modeled as a single, linear element cap ...

are relatively long, and the first pair of legs in males is extremely reduced in size. Like other paeromopodids, species of ''Paeromopus'' have fine parallel grooves (striae or striations) on each body segment, giving a somewhat roughened appearance. The simple eyes (

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 ...

) occur in two patches- one on each side of the head; each patch may include up to 31 ocelli of unequal sizes, arranged in rows.

Distribution

There are four species of ''Paeromopus''. ''P. angusticeps,'' divided into two

subspecies In Taxonomy (biology), biological classification, subspecies (: subspecies) is a rank below species, used for populations that live in different areas and vary in size, shape, or other physical characteristics (Morphology (biology), morpholog ...

, has the largest geographical range, occupying much of

in a large arc extending from

Monterey County Monterey County ( ), officially the County of Monterey, is a county located on the Pacific coast in the U.S. state of California. As of the 2020 United States census, its population was 439,035. The county's largest city and county seat is ...

on the central coast, north along the

Coast Ranges The Pacific Coast Ranges (officially gazetted as the Pacific Mountain System in the United States; ; ) are the series of mountain ranges that stretch along the West Coast of North America from Alaska south to Northern and Central Mexico. Althoug ...

to Humboldt County, and descending along the Cascades and

range of eastern California. Each of the remaining three species are known from relatively few locations within the Sierra Nevada .

Taxonomy

The genus ''Paeromopus'' was first named in 1881 by German entomologist

, however the earliest-named species now assigned to ''Paeromopus'', ''P. angusticeps'', was described in 1864 by the American naturalist Horatio C Wood under the name ''Spirobolus angusticeps'', based on specimens collected in

San Francisco San Francisco, officially the City and County of San Francisco, is a commercial, Financial District, San Francisco, financial, and Culture of San Francisco, cultural center of Northern California. With a population of 827,526 residents as of ...

. In 1881 Karsch described a species he named ''Paeromopus lysiopetalinus'', which was the first establishment of the genus "''Paeromopous".'' In 1949, Ralph V. Chamberlin suggested that "''S. angusticeps"'' belonged to the genus ''Paeromopus'', and renamed it ''P. angusticeps.'' Subsequently ''P. lysiopetalinus'' was recognized as a

taxonomic synonym In taxonomy, the scientific classification of living organisms, a synonym is an alternative scientific name for the accepted scientific name of a taxon. The Botanical nomenclature, botanical and Zoological nomenclature, zoological codes of nomencl ...

of ''P. angusticeps''- a different name applied to what turned out to be the same species. ''Paeromopus ''is now recognized as a member of the family Paeromopodidae in the order

Julida Julida is an 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 structures. Addit ...

, while '' Spirobolus'' proper belongs to the family Spirobolidae of the order

Spirobolida Spirobolida is an Order (biology), order of "round-backed" millipedes containing approximately 500 species in 12 family (biology), families. Its members are distinguished by the presence of a "pronounced Suture (anatomy), suture that runs "verti ...

. Additional species of paeromopodids were described throughout the 20th century. In 1938, German entomologist

Karl Wilhelm Verhoeff Karl (or Carl) Wilhelm Verhoeff (25 November 1867 – 6 December 1945) was a German myriapodologist and entomologist, specialising in myriapods (millipedes, centipedes, and related species) as well as woodlice and to a lesser extent insects. Bio ...

described the species ''Paeromopellus sphinx,'' and at least eight species of ''Paeromopus'' have been proposed, but subsequently several named species and ''Paeromopellus'' were brought into synonymy with previously named species, or assigned to the closely related genus '' Californiulus.'' The most recently described species was ''P. paniculus'', described in 1997. The meaning of the name ''Paeromopus'' was not specified by Karsch, although the suffix ''-pus'' refers to legs.

References

{{Taxonbar, from=Q4298013 Julida Millipedes of North America Endemic fauna of California Taxa named by Ferdinand Karsch