''Devillea'' 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 flat-backed millipedes in the family Xystodesmidae. These

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 are rare and limited to caves. Species in this genus are found in

Sardinia Sardinia ( ; ; ) is the Mediterranean islands#By area, second-largest island in the Mediterranean Sea, after Sicily, and one of the Regions of Italy, twenty regions of Italy. It is located west of the Italian Peninsula, north of Tunisia an ...

Capri Capri ( , ; ) is an island located in the Tyrrhenian Sea off the Sorrento Peninsula, on the south side of the Gulf of Naples in the Campania region of Italy. A popular resort destination since the time of the Roman Republic, its natural beauty ...

, and southern

France France, officially the French Republic, is a country located primarily in Western Europe. Overseas France, Its overseas regions and territories include French Guiana in South America, Saint Pierre and Miquelon in the Atlantic Ocean#North Atlan ...

in the

Maritime Alps The Maritime Alps ( ; ) are a mountain range in the southwestern part of the Alps. They form the border between the regions of France, French region of Provence-Alpes-Côte d'Azur and the regions of Italy, Italian regions of Piedmont and Liguria ...

. These species are notable for featuring more than the 20 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) usually found in the order

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 ...

. This genus is one of only two genera in this order to feature these extra segments and the first such genus to be discovered.

Discovery

The French myriapodologist Henri W. Brölemann created this genus to contain the newly discovered

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 ...

'' D. tuberculata'' in 1902. The original descriptions of this genus and this species are based on multiple specimens of each sex collected from caves near Tourettes-sur-Loup and in Saint-Jeannet near Vence, both in the Provence-Alpes-Côte d’Azur region of southern France in the Maritime Alps. Brölemann named this genus for M.J. Sainte-Claire Deville, who collected these specimens.

Description

Millipedes in this genus feature

exoskeleton An exoskeleton () . is a skeleton that is on the exterior of an animal in the form of hardened integument, which both supports the body's shape and protects the internal organs, in contrast to an internal endoskeleton (e.g. human skeleton, that ...

s that are highly sculptured with

tubercle In anatomy, a tubercle (literally 'small tuber', Latin for 'lump') is any round nodule, small eminence, or warty outgrowth found on external or internal organs of a plant or an animal. In plants A tubercle is generally a wart-like projectio ...

s. Species in this genus are small, usually less than 10 mm long. The type species ''D. tuberculata'', for example, reaches only 8 mm in length. The second species in this genus to be discovered, '' D. doderoi'', described in 1903 based on a male specimen found in Sardinia, measures only 8 mm in length. The species '' D. cerrutii'' and '' D. patrizii'', described in 1956 based on specimens (including only one adult of each species, both female) found in Sardinia, reach 10 mm and 7 mm in length, respectively. The most striking characteristic of this genus, however, is the number of segments. Each species of ''Devillea'' features more than the 20 segments (that is, 19 rings plus the telson) typically observed in flat-backed millipedes. In the type species ''D. tuberculata'', adult males have 21 segments, and adult females have 22, with a corresponding increase in the number of leg pairs (32 in adult males, excluding one pair 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 millipe ...

s, and 35 in adult females). The species ''D. cerrutii'' and ''D. patrizii'' also feature 22 segments in females. Some species in this genus also exhibit variation in segment number within the same sex. For example, in '' D. subterranea'', described in 1943 based on specimens from Capri, adult males can have as few as 19 segments or as many as 23. Similarly, in the species '' D. sanctijohannis'', originally described in 1974 as a subspecies of ''D. doderoi'' based on specimens found in Sardinia, adult males can have 19 to 22 segments, and adult females can have 20 to 24 segments. The species ''D. doderoi'' represents the most extreme example, ranging from 25 to as many as 29 segments, the maximum number recorded in this genus.

Development

Little is known about the post-embryonic development of millipedes in this genus. For example, some species in this genus may be euanamorphic; that is, they may continue to molt and add an indefinite number of segments as adults. Authorities believe that species in this genus go through the stages of

anamorphosis Anamorphosis is a distorted projection that requires the viewer to occupy a specific vantage point, use special devices, or both to view a recognizable image. It is used in painting, photography, sculpture and installation, toys, and film speci ...

usually observed in the order Polydesmida, then reach a greater number of segments through additional molts, adding one segment per molt.

Species

This genus includes six species: * '' Devillea cerrutii'' Manfredi, 1956 * '' Devillea doderoi'' Silvestri, 1903 * '' Devillea patrizii'' Manfredi, 1956 * '' Devillea sanctijohannis'' Strasser, 1974 * '' Devillea subterranea'' Verhoeff, 1943 * '' Devillea tuberculata'' Brölemann, 1902

References

{{taxonbar, from1=Q6450255 Xystodesmidae Millipede genera Millipedes of Europe Taxa named by Henry Wilfred Brolemann