Yllenus

{{Short description| Genus of spiders}}

{{Automatic taxobox

| taxon = Yllenus

| authority = Simon, 1868

| type_species = Y. arenarius

| type_species_authority = Simon, 1868

| subdivision_ranks = Species

| subdivision = 18, see text

}}

Yllenus is a genus of jumping spiders that was first described by Eugène Louis Simon in 1868.{{cite journal| last=Simon| first=E.| year=1868| title=Monographie des espèces européennes de la famille des attides (Attidae Sundewall. - Saltigradae Latreille)| journal=Annales de la Société Entomologique de France| pages=529–726| volume=8| issue=4| author-link=Eugène Simon}} Until 2019,{{cite journal| last1=Marusik| first1=Y. M.| last2=Blick| first2=T.| year=2019| title=Further new synonyms of jumping spider genera (Araneae: Salticidae)| journal=Arachnologische Mitteilungen| volume=57| page=89| issue=1| doi=10.30963/aramit5717| doi-access=free}} it was considered a senior synonym of Pseudomogrus, and many of the species formerly placed here were transferred to new genera Logunyllus and Marusyllus by Jerzy Prószyński in 2016.{{cite journal| last=Prószyński| first=J.| year=1968| title=Systematic revision of the genus Yllenus Simon, 1868 (Araneida, Salticidae)| journal=Annales Zoologici, Warszawa| volume=26| page=415| author-link=Jerzy Prószyński}}

Y. arenarius is peculiar in building silken nests under the sand surface of sandy dunes it inhabits.{{Cite journal| last1=Bartos| first1=Maciej| year=2002| title=The sub-sand nests of Yllenus arenarius (Araneae, Salticidae): Structure, function and construction behavior| journal=The Journal of Arachnology| volume=30| issue=2| pages=275–280| doi=10.1636/0161-8202(2002)030[0275:TSSNOY]2.0.CO;2| jstor=3706271| s2cid=86508594| url=https://www.biodiversitylibrary.org/part/227118}}