''Deharvengius'' is a

monotypic In biology, a monotypic taxon is a taxonomic group (taxon) that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or smaller, infraspecific taxa. In the case of genera, the term "unisp ...

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 flat-backed millipede in the

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

Trichopolydesmidae, and ''Deharvengius bedosae'' is the only

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

in this genus. This

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 ...

is notable as one of the very few species 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 ...

Polydesmida Polydesmida (from the Greek ''poly'' "many" and ''desmos'' "bond") is the largest order of millipedes, with more than 5,000 species, including all the millipedes reported to produce hydrogen cyanide (HCN). This order is also the most diverse of ...

to feature adults with only 18 segments (counting the collum as the first segment and the

telson The telson () is the hindmost division of the body of an arthropod. Depending on the definition, the telson is either considered to be the final segment (biology), segment of the arthropod body, or an additional division that is not a true segm ...

as the last) rather than the 20 segments usually found in this order. This species is found in

Vietnam Vietnam, officially the Socialist Republic of Vietnam (SRV), is a country at the eastern edge of mainland Southeast Asia, with an area of about and a population of over 100 million, making it the world's List of countries and depende ...

Discovery

This genus and its

type species In International_Code_of_Zoological_Nomenclature, zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the spe ...

were first described in 2014 by the

biologists A biologist is a scientist who conducts research in biology. Biologists are interested in studying life on Earth, whether it is an individual cell, a multicellular organism, or a community of interacting populations. They usually specialize in ...

Sergei Golovatch, Jean-Jacques Geoffroy, and Didier VandenSpiegel. They based the original description of this genus and its only species on a male

holotype A holotype (Latin: ''holotypus'') is a single physical example (or illustration) of an organism used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of s ...

and twelve paratypes (three males, four females, and five juveniles). This genus and this species are named in honor of the biologists Louis Deharveng and Anne Bedos of the

Muséum National d’Histoire Naturelle The French National Museum of Natural History ( ; abbr. MNHN) is the national natural history museum of France and a of higher education part of Sorbonne University. The main museum, with four galleries, is located in Paris, France, within the Ja ...

Paris Paris () is the Capital city, capital and List of communes in France with over 20,000 inhabitants, largest city of France. With an estimated population of 2,048,472 residents in January 2025 in an area of more than , Paris is the List of ci ...

. Deharveng and Bedos extracted the type specimens from soil collected in 2008 in the

district A district is a type of administrative division that in some countries is managed by the local government. Across the world, areas known as "districts" vary greatly in size, spanning regions or county, counties, several municipality, municip ...

of Kien Luong in Kien Giang

province A province is an administrative division within a country or sovereign state, state. The term derives from the ancient Roman , which was the major territorial and administrative unit of the Roman Empire, Roman Empire's territorial possessions ou ...

in Vietnam. The holotype and nine paratypes are deposited in the Muséum National d’Histoire Naturelle, and one male paratype is deposited in the Zoological Museum of the State University of Moscow.

Description

The adults of this species measure about 3 mm in length and feature only 18 segments in each sex. These millipedes are uniformly pale with a surface that is dull and often almost translucent. The head in each sex is flattened. The antennae are short and shaped like clubs, with the sixth segment of each antenna abruptly and especially enlarged. The dorsal surface of each segment features three transverse rows of long tergal

setae In biology, setae (; seta ; ) are any of a number of different bristle- or hair-like structures on living organisms. Animal setae Protostomes Depending partly on their form and function, protostome setae may be called macrotrichia, chaetae ...

, with two pairs of simple pointed setae per row on each segment following the collum. The ozopores are shaped like ovals and arranged according to the normal pore formula for millipedes in the order Polydesmida, with pores on segments 5, 7, 9, 10, 12, 13, and from 15 to the penultimate segment. The paranota are very poorly developed and reduced to delicate serrate ridges along the lateral edges with sharp teeth at the rear corners of segments with pores. With only 18 segments, adult females feature only 27 pairs of legs, whereas adult males feature 26 pairs of walking legs (excluding the eighth leg pair, which become

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 millipe ...

). The legs in ''D. bedosae'' are short and feature claws that are simple and slightly curved. The telopodite (distal element) of each gonopod is clearly exposed rather than hidden in a cavity, but these telopodites are pressed close against the ventral surface. Each telopodite is slender, curved into a semicircle, and directed laterally toward the opposite side so that they cross one another and overlap. Neither a groove nor a ridge separates the basal (prefemoral) half of each telopodite from the acropodite (the distal half). Each telopodite features two branches at the distal end, a small solenophore and a longer solenomere. The solenomere is simple, slender, and shaped like a curved spine. The seminal groove runs mostly along the ventral and lateral surface of the obviously twisted acropodite to terminate at the distal end of the solenomere. This millipede exhibits many traits commonly observed in the family Trichopolydesmidae. For example, like all known species in this family, this millipede features segments with three transverse rows of tergal setae. Furthermore, this millipede also exhibits the normal pore formula usually observed in this family. Moreover, as in most species in this family, the seminal groove in the males of this species terminates distally on a separate branch (solenomere) of the telopodite. Several unusual traits, however, distinguish this genus from most other genera in the same family. For example, this genus is exceptional in featuring only 18 segments in each sex. Furthermore, this genus is unusual in featuring only four rather than six tergal setae in each transverse row, and the head in this genus is less convex than usually observed in this family. Moreover, the gonopods in this genus are very distinctive, with long simple telopodites curved into crossing semicircles.

References

{{Taxonbar, from1=Q106635131, from2=Q106635566 Polydesmida Monotypic myriapod genera Millipede genera Arthropods of Asia