# Armadillidium

Armadillidium (/ɑːrmədɪˈlɪdiəm/) is a genus of the small terrestrial crustacean known as the woodlouse. Armadillidium are also commonly known as pill woodlice, leg pebbles, pill bugs, roly-poly, or potato bugs, and are often confused with pill millipedes such as Glomeris marginata. They are characterised by their ability to roll into a ball ("volvation") when disturbed.

## Distribution and habitat

They chiefly feed on decaying organic matter like leaves, decomposed wood fibers, and less so on other organic material like lichens. They are usually found in moist areas such as decomposing leaf matter and soil. Armadillidium vulgare is the most abundant species in Europe and has been introduced worldwide. However, the vast majority of species are endemic to small regions close to the Mediterranean Sea, in much lower numbers than common species such as A. vulgare, and hence are understudied.

## Description

Unlike other terrestrial arthropods such as insects and spiders, pill bugs do not have a waxy cuticle that would reduce evaporation from their bodies. Pill bugs also use modified lungs, called pseudotrachea, for respiration, and the lungs must remain moist to function. Individual pill bugs typically live for two or three years, and females brood eggs once or twice each summer. In larger species and individuals, up to over an hundred eggs are brooded at a time in the marsupium, a pocket on the ventral side of the female pill bug. The marsupium provides nutrients and oxygen to the eggs until the hatch, resulting in a sort of “live birth”.
The colouration especially of young A. klugii resembles the red hourglass marking of the Mediterranean black widow Latrodectus tredecimguttatus. This is probably a kind of mimicry, to ward off predators that mistake the harmless animal for a venomous spider.

## Species

* Armadillidium depressum
* Armadillidium granulatum
* Armadillidium lagrecai
* Armadillidium pictum
* Armadillidium pulchellum
* Armadillidium vulgare
* Armadillidium nasatum
* Macro shot of an Armadillidium opacum
* Armadillidium gestroi
* Armadillidium pallasii
* Armadillidium versicolor
* Armadillidium album
* Armadillidium atticum
* Armadillidium marmoratum
There are 189 recognised species in the genus Armadillidium:
* Armadillidium absoloni Strouhal, 1939
* Armadillidium aegaeum Strouhal, 1929
* Armadillidium aelleni Caruso & Ferrara, 1982
* Armadillidium alassiense Verhoeff, 1910
* Armadillidium albigauni Arcangeli, 1935
* Armadillidium albomarginatum Verhoeff, 1901
* Armadillidium album Dollfus, 1887
* Armadillidium ameglioi Arcangeli, 1914
* Armadillidium amicorum Rodriguez & Vicente, 1993
* Armadillidium anconanum Verhoeff, 1928
* Armadillidium angulatum Koelbel, 1891
* Armadillidium apenninigenum Verhoeff, 1936
* Armadillidium apenninorum Verhoeff, 1928
* Armadillidium apfelbecki Dollfus, 1895
* Armadillidium apuanum Taiti & Ferrara, 1995
* Armadillidium arcadicum Verhoeff, 1902
* Armadillidium arcangelii Strouhal, 1929
* Armadillidium argentarium Verhoeff, 1931
* Armadillidium argolicum Verhoeff, 1907
* Armadillidium artense Strouhal, 1956
* Armadillidium assimile Budde-Lund, 1885
* Armadillidium atticum Strouhal, 1929
* Armadillidium azerbaidzhanum Schmalfuss, 1990
* Armadillidium badium Budde-Lund, 1885
* Armadillidium baldense Verhoeff, 1902
* Armadillidium banaticum Verhoeff, 1907
* Armadillidium beieri Strouhal, 1937
* Armadillidium bensei Schmalfuss, 2006
* Armadillidium bicurvatum Verhoeff, 1901
* Armadillidium boalense Cifuentes, Robla & Garcia, 2024
* Armadillidium bosniense Strouhal, 1939
* Armadillidium boukorninense Hamaied, Charfi-Cheikhrouha & Lombardo, 2018
* Armadillidium brentanum Verhoeff, 1932
* Armadillidium bulgaricum Frankenberger, 1941
* Armadillidium calabricum Verhoeff, 1908
* Armadillidium canaliferum Verhoeff, 1908
* Armadillidium capreae Verhoeff, 1944
* Armadillidium carniolense Verhoeff, 1901
* Armadillidium carynthiacum Verhoeff, 1939
* Armadillidium cavannai Arcangeli, 1960
* Armadillidium cephalonicum Strouhal, 1929
* Armadillidium chazaliei Dollfus, 1896
* Armadillidium clausi Verhoeff, 1901
* Armadillidium clavigerum Verhoeff, 1928
* Armadillidium corcyraeum Verhoeff, 1901
* Armadillidium cruzi Garcia, 2003
* Armadillidium cythereium Strouhal, 1937
* Armadillidium dalmaticum Strouhal, 1939
* Armadillidium decorum Brandt, 1833
* Armadillidium delattini Verhoeff, 1943
* Armadillidium depressum Brandt in Brandt & Ratzeburg, 1831
* Armadillidium djebalensis Vandel, 1958
* Armadillidium dollfusi Verhoeff, 1902
* Armadillidium elysii Verhoeff, 1936
* Armadillidium epiroticum Strouhal, 1956
* Armadillidium espanyoli Cruz, 1992
* Armadillidium esterelanum Dollfus, 1887
* Armadillidium etruriae Ferrara & Taiti, 1978
* Armadillidium euxinum Verhoeff, 1929
* Armadillidium fallax Brandt, 1833
* Armadillidium ficalbii Arcangeli, 1911
* Armadillidium flavoscutatum Strouhal, 1927
* Armadillidium fossuligerum Verhoeff, 1902
* Armadillidium frontemarginatum Strouhal, 1927
* Armadillidium frontetriangulum Verhoeff, 1901
* Armadillidium furcatum Budde-Lund, 1885
* Armadillidium galiciense Schmölzer, 1955
* Armadillidium germanicum Verhoeff, 1901
* Armadillidium gestroi Tua, 1900
* Armadillidium ghardalamensis Caruso & Hili, 1991
* Armadillidium gionum Schmalfuss, 2012
* Armadillidium granulatum Brandt, 1833
* Armadillidium grimmi Schmalfuss, 2006
* Armadillidium hauseni Schmalfuss, 1985
* Armadillidium herzegowinense Verhoeff, 1907
* Armadillidium hessei Verhoeff, 1930
* Armadillidium hirtum Budde-Lund, 1885
* Armadillidium humectum Strouhal, 1937
* Armadillidium ibericum Cifuentes & Escarabajal Bernabé, 2022
* Armadillidium ichkeuli Hamaied & Charfi-Cheikhrouha, 2017
* Armadillidium insulanum Verhoeff, 1907
* Armadillidium irmengardis Strouhal, 1956
* Armadillidium janinense Verhoeff, 1902
* Armadillidium jaqueti Dollfus in Jaquet, 1898
* Armadillidium jerrentrupi Schmalfuss, 2008
* Armadillidium jonicum Strouhal, 1927
* Armadillidium justi Strouhal, 1937
* Armadillidium kalamatense Verhoeff, 1907
* Armadillidium kalamium Strouhal, 1956
* Armadillidium klaptoczi Verhoeff, 1908
* Armadillidium klugii Brandt, 1833
* Armadillidium kochi Dollfus, 1887
* Armadillidium kossuthi Arcangeli, 1929
* Armadillidium kuehnelti Schmalfuss, 2006
* Armadillidium laconicum Strouhal, 1938
* Armadillidium lagrecai Vandel, 1969
* Armadillidium laminigerum Verhoeff, 1907
* Armadillidium lanzai Taiti & Ferrara, 1996
* Armadillidium littorale Taiti & Ferrara, 1996
* Armadillidium lobocurvum Verhoeff, 1902
* Armadillidium lymberakisi Schmalfuss, Paragamian & Sfenthourakis, 2004
* Armadillidium maccagnoi Arcangeli, 1960
* Armadillidium maculatum (Risso, 1816)
* Armadillidium maniatum Schmalfuss, 2006
* Armadillidium mareoticum Budde-Lund, 1885
* Armadillidium marinense Verhoeff, 1902
* Armadillidium marinensium Verhoeff, 1928
* Armadillidium marmoratum Strouhal, 1929
* Armadillidium marmorivagum Verhoeff, 1934
* Armadillidium messenicum Verhoeff, 1902
* Armadillidium meteorense Schmalfuss, 2012
* Armadillidium mohamedanicum Verhoeff, 1929
* Armadillidium nahumi Garcia, 2020
* Armadillidium narentanum Verhoeff, 1907
* Armadillidium nasatum Budde-Lund, 1885
* Armadillidium nigrum Arcangeli, 1956
* Armadillidium obenbergi Frankenberger, 1941
* Armadillidium odhneri Verhoeff, 1930
* Armadillidium oglasae Ferrara & Taiti, 1978
* Armadillidium opacum (C. Koch, 1841)
* Armadillidium ormeanum Verhoeff, 1931
* Armadillidium paeninsulae Ferrara & Taiti, 1978
* Armadillidium pallasii Brandt, 1833
* Armadillidium pallidum Verhoeff, 1907
* Armadillidium pangaionum Schmalfuss, 2008
* Armadillidium panningi Strouhal, 1937
* Armadillidium pardoi Vandel, 1956
* Armadillidium pelionense Strouhal, 1928
* Armadillidium peloponnesiacum Verhoeff, 1901
* Armadillidium peraccae Tua, 1900
* Armadillidium petralonense Schmalfuss, 2008
* Armadillidium phalacronum Schmalfuss, 2008
* Armadillidium pictum Brandt, 1833
* Armadillidium pieperi Schmalfuss, 2008
* Armadillidium pilosellum Dollfus, 1896
* Armadillidium ponalense Verhoeff, 1934
* Armadillidium portofinense Verhoeff, 1908
* Armadillidium pretusi Cruz, 1992
* Armadillidium pseudassimile Taiti & Ferrara, 1980
* Armadillidium pseudovulgare Verhoeff, 1902
* Armadillidium pulchellum (Zenker in Panzer, 1799)
* Armadillidium quinquepustulatum Budde-Lund, 1885
* Armadillidium rhodopinum Verhoeff, 1936
* Armadillidium rojanum Verhoeff, 1936
* Armadillidium rosai Arcangeli, 1913
* Armadillidium ruffoi Arcangeli, 1940
* Armadillidium rupium Verhoeff, 1928
* Armadillidium sanctum Dollfus, 1892
* Armadillidium savonense Verhoeff, 1931
* Armadillidium saxivagum Verhoeff, 1901
* Armadillidium scaberrimum Stein, 1859
* Armadillidium scabrum Dollfus, 1892
* Armadillidium schmalfussi Caruso & Lombardo, 1982
* Armadillidium serrai Cruz & Dalens, 1990
* Armadillidium serratum Budde-Lund, 1885
* Armadillidium sfenthourakisi Schmalfuss, 2008
* Armadillidium siculorum Verhoeff, 1908
* Armadillidium silvestrii Verhoeff, 1931
* Armadillidium simile Strouhal, 1937
* Armadillidium simoni Dollfus, 1887
* Armadillidium sordidum Dollfus, 1887
* Armadillidium stagnoense Verhoeff, 1902
* Armadillidium steindachneri Strouhal, 1927
* Armadillidium stolikanum Verhoeff, 1907
* Armadillidium storkani Frankenberger, 1941
* Armadillidium strinatii Vandel, 1961
* Armadillidium stymphalicum Schmalfuss, 2006
* Armadillidium sulcatum H. Milne Edwards, 1840
* Armadillidium tabacarui Gruia, Iavorschi & Sarbu, 1994
* Armadillidium teramense Verhoeff, 1933
* Armadillidium tigris Budde-Lund, 1885
* Armadillidium tirolense Verhoeff, 1901
* Armadillidium torchiai Taiti & Ferrara, 1996
* Armadillidium traiani Demianowicz, 1932
* Armadillidium tripolitzense Verhoeff, 1902
* Armadillidium tuberculatum Schmalfuss, 2008
* Armadillidium tunetanum Verhoeff, 1907
* Armadillidium tunisiense Hamaïed & Charfi-Cheikhrouha, 2007
* Armadillidium tyrrhenum Taiti & Ferrara, 1980
* Armadillidium vallombrosae Verhoeff, 1907
* Armadillidium valonae Arcangeli, 1952
* Armadillidium verhoeffi Rogenhofer, 1915
* Armadillidium versicolor Stein, 1859
* Armadillidium versluysi Strouhal, 1937
* Armadillidium virgo Caruso & Bouchon, 2011
* Armadillidium vulgare (Latreille, 1804)
* Armadillidium werneri Strouhal, 1927
* Armadillidium xerovunense Strouhal, 1956
* Armadillidium zangherii Arcangeli, 1924
* Armadillidium zenckeri Brandt, 1833