Theridion is a genus of tangle-web spiders with a worldwide distribution. Notable species are the Hawaiian happy face spider (T. grallator), named for the iconic symbol on its abdomen, and T. nigroannulatum, one of few spider species that lives in social groups, attacking prey en masse to overwhelm them as a team.
Identification Spiders in this genus are about as long or longer than they are wide. Their chelicerae have two or less teeth on the front edge and none on the back edge. The front leg is the longest in both genders, but the next longest is the second leg in males and the fourth leg in females. The epigyne can vary, but the pedipalp has a median apophysis and a colulus is absent from both genders. In several species, the males have mastidia (projections) on the chelicerae.
Theridion has the anterior eye row slightly curved and with a gap between it and the posterior eye row. This distinguishes it from Enoplognatha, another theridiid genus in which the anterior eye row is almost straight and the gap between eye rows is very small.
Ecology Theridion build tangle webs, usually under leaves and among vegetation. At night, spiders hang upside-down in these webs. During the day, they hide close by their webs.
Philodromus cespitum, a species of running crab spider, preys on Theridion spiders in European fruit orchards.
Mating Mating behaviour has been studied in several Theridion species. It involves pseudocopulation, numerous sperm inductions and copulatory sequences. The male approaches the female to mate, usually in the latter's retreat (a hood-shaped part of the web where the female lives in). Male Theridion perform contralateral insertions, inserting their left palp into the female's right introductory duct and vice versa for the right palp. Female Theridion are less aggressive after mating compared to other genera of theridiids.
Species , this genus includes 572 species and three subspecies. However, the genus has traditionally been assigned species that lack a colulus and did not fit into other genera (wastebasket taxon). New species continue to be described on a regular basis.
These species have articles on Wikipedia:
Theridion albidum Banks, 1895 – Canada, United States Theridion albocinctum Urquhart, 1892 – New Zealand Theridion albomaculosum O. Pickard-Cambridge, 1869 – Sri Lanka Theridion ampliatum Urquhart, 1892 – New Zealand Theridion argentatulum Roewer, 1942 – New Zealand Theridion attritum (Simon, 1908) – Australia (Western Australia) Theridion californicum Banks, 1904 – Canada, United States Theridion cheimatos Gertsch & Archer, 1942 – United States Theridion cruciferum Urquhart, 1886 – New Zealand Theridion cuspulatum Schmidt & Krause, 1998 – Cape Verde Theridion differens Emerton, 1882 – Canada, United States Theridion dilutum Levi, 1957 – United States, Mexico Theridion elegantissimum Roewer, 1942 – Taiwan Theridion flabelliferum Urquhart, 1887 – New Zealand Theridion flavonotatum Becker, 1879 – United States, Cuba, Turks & Caicos Theridion frondeum Hentz, 1850 – Canada, United States, Bahamas Theridion gabardi Simon, 1895 – Sri Lanka Theridion glaucescens Becker, 1879 – Canada, United States Theridion gracilipes Urquhart, 1889 – New Zealand Theridion grallator Simon, 1900 – Hawaii Theridion himalayanum Priyadarshini & Tripathy, 2026 – India (Uttarakhand) Theridion incertissimum (Caporiacco, 1954) – French Guiana, Brazil Theridion kawea Levi, 1957 – United States, Mexico Theridion lawrencei Gertsch & Archer, 1942 – Canada, United States Theridion leechi Gertsch & Archer, 1942 – Canada, United States Theridion llano Levi, 1957 – United States Theridion logan Levi & Patrick, 2013 – United States Theridion longicrure Marples, 1956 – New Zealand Theridion luteitarse Schmidt & Krause, 1995 – Cape Verde Theridion melanurum Hahn, 1831 – Macaronesia, North Africa, Europe, Turkey, Caucasus, Russia (Europe to Middle Siberia), Middle East. Introduced to Canada, United States Theridion michelbacheri Levi, 1957 – United States Theridion modestum (Simon, 1894) – Sri Lanka Theridion murarium Emerton, 1882 – Canda, United States, Mexico Theridion neomexicanum Banks, 1901 – Canada, United States Theridion neshamini Levi, 1957 – United States Theridion nodiferum Simon, 1895 – Sri Lanka Theridion pennsylvanicum Emerton, 1913 – Canada, United States Theridion pictum (Walckenaer, 1802) – North America, Europe, North Africa, Caucasus, Russia (Europe to Far East), Kazakhstan, Turkemenistan, China, Japan. Introduced to South Africa (type species) Theridion porphyreticum Urquhart, 1889 – New Zealand Theridion punctipes Emerton, 1924 – United States, Mexico Theridion punicapunctatum Urquhart, 1891 – New Zealand Theridion quadratum (O. Pickard-Cambridge, 1882) – Sri Lanka, Indonesia (Sumatra) Theridion rabuni Chamberlin & Ivie, 1944 – Canada, United States, Bahamas Theridion squalidum Urquhart, 1886 – New Zealand Theridion strepitus Peck & Shear, 1987 – Galapagos Theridion submissum Gertsch & Davis, 1936 – United States, Mexico, Bahama Is. Jamaica Theridion teliferum Simon, 1895 – Sri Lanka Theridion varians Hahn, 1833 – Europe, North Africa, Turkey, Caucasus, Russia (Europe to Far East), Kazakhstan, Iran, Central Asia, China. Introduced to Canada, United States Theridion viridanum Urquhart, 1887 – New Zealand Theridion zantholabio Urquhart, 1886 – New Zealand Theridion zonulatum Thorell, 1890 – India, China, Thailand, Singapore, Indonesia (Sumatra, Borneo)
T. abruptum Simon, 1884 – Sudan T. acanthopodum Gao & Li, 2014 – China T. accoense Levy, 1985 – Israel T. acutitarse Simon, 1900 – Hawaii T. adjacens (O. Pickard-Cambridge, 1896) – Mexico to Panama T. adrianopoli Drensky, 1915 – North Macedonia, Bulgaria, Albania, Greece (incl. Crete), Turkey T. aeolium Levi, 1963 – United States T. agrarium Levi, 1963 – Brazil T. agreste Nicolet, 1849 – Chile T. agrifoliae Levi, 1957 – Canada, United States T. akme Levi, 1959 – Panama T. akron Levi, 1959 – Panama T. albidorsum Strand, 1909 – South Africa T. albidum Banks, 1895 – Canada, United States T. albioculum Zhu, 1998 – China T. albipes L. Koch, 1878 – Caucasus (Russia, Georgia) T. albocinctum Urquhart, 1892 – New Zealand T. albodecoratum Rainbow, 1916 – Australia (Queensland) T. albolineatum Nicolet, 1849 – Chile T. albolineolatum Caporiacco, 1940 – Ethiopia T. albomaculosum O. Pickard-Cambridge, 1869 – Sri Lanka T. albopictum Thorell, 1898 – Myanmar T. albostriatum (L. Koch, 1867) – New Guinea, Australia (Queensland, Norfolk Is.), Tonga T. albulum O. Pickard-Cambridge, 1898 – Panama T. amarga Levi, 1967 – Chile, Argentina T. amatitlan Levi, 1963 – Guatemala T. ambiguum Nicolet, 1849 – Chile T. ampascachi Mello-Leitão, 1941 – Argentina T. ampliatum Urquhart, 1892 – New Zealand T. angusticeps Caporiacco, 1949 – Kenya T. angustifrons Caporiacco, 1934 – Pakistan T. anson Levi, 1967 – Chile (Juan Fernandez Is.) T. antillanum Simon, 1894 – Caribbean T. apiculatum Roewer, 1942 – Australia (Queensland) T. aporum Levi, 1963 – Brazil T. apostoli Mello-Leitão, 1945 – Argentina T. apulco Levi, 1959 – Mexico T. aragua Levi, 1963 – Venezuela T. archeri Levi, 1959 – Cuba T. argentatulum Roewer, 1942 – New Zealand T. ariel Bellvert & Arnedo, 2021 – Hawaii T. arizonense Levi, 1957 – United States T. arsia Zamani & Marusik, 2021 – Iran, Kazakhstan T. artum Levi, 1959 – Panama, Trinidad T. aruanum Strand, 1911 – Indonesia (Aru Is.) T. arushae Caporiacco, 1947 – Tanzania T. asbolodes Rainbow, 1917 – Australia (South Australia) T. asopi Vanuytven, 2014 – Western and Central Europe, Italy T. astrigerum Thorell, 1895 – Myanmar T. atratum Thorell, 1877 – Indonesia (Sulawesi) T. attritum (Simon, 1908) – Australia (Western Australia) T. auberti Simon, 1904 – South Africa T. aulos Levi, 1963 – Brazil T. australe Banks, 1899 – United States, Mexico, Caribbean T. baccula Thorell, 1887 – Myanmar T. baltasarense Levi, 1963 – Windward Is. T. banksi Berland, 1920 – East Africa T. barbarae Levi, 1959 – Mexico T. beebei Levi, 1963 – Venezuela T. bellatulum Levi, 1963 – Brazil T. bengalense Sen, Saha & Raychaudhuri, 2011 – India T. bergi Levi, 1963 – Brazil, Paraguay, Argentina T. berlandi Roewer, 1942 – Samoa T. bernardi Lecigne, 2017 – Portugal T. betteni Wiehle, 1960 – Europe, Turkey T. bicruciatum Roewer, 1961 – Senegal, Mozambique, South Africa, Eswatini T. bidepressum Yin, Peng & Zhang, 2005 – China T. biezankoi Levi, 1963 – Brazil T. biforaminum Gao & Zhu, 1993 – China T. biolleyi Banks, 1909 – Costa Rica T. biseriatum Thorell, 1890 – Indonesia (Sumatra) T. bisignatum (Mello-Leitão, 1945) – Brazil, Argentina T. bitakum Barrion & Litsinger, 1995 – Philippines T. blaisei Simon, 1909 – Vietnam T. boesenbergi Strand, 1904 – Europe, Caucasus T. bolivari Levi, 1959 – Mexico T. bolum Levi, 1963 – Brazil T. bomae Schmidt, 1957 – DR Congo T. bosniense Wunderlich, 2011 – Bosnia and Herzegovina T. botanicum Levi, 1963 – Venezuela T. brachypus Thorell, 1887 – Myanmar T. bradyanum Strand, 1907 – South Africa T. brunellii Caporiacco, 1940 – Ethiopia T. brunneonigrum Caporiacco, 1949 – Kenya T. bryantae Roewer, 1951 – Mexico T. bullatum Tullgren, 1910 – Tanzania T. buxtoni Berland, 1929 – Samoa, French Polynesia (Society Is., Tuamotu Arch.), Pitcairn Is. (Henderson Is.) T. cairoense Wunderlich, 2011 – Egypt T. calcynatum Holmberg, 1876 – Venezuela to Argentina T. caliban Bellvert & Arnedo, 2021 – Hawaii T. californicum Banks, 1904 – Canada, United States T. caliginosum Marples, 1955 – Samoa T. cameronense Levi, 1957 – United States, Mexico T. carinatum Yin, Peng & Zhang, 2005 – China T. carpathium Brignoli, 1984 – Greece T. cassinicola Simon, 1907 – Guinea-Bissau T. castaneum Franganillo, 1931 – Cuba T. catharina Marples, 1955 – Samoa T. cavipalpus (F. O. Pickard-Cambridge, 1902) – Guatemala T. cazieri Levi, 1959 – Bahama Is. T. centrum Levi, 1959 – Panama T. ceres Bellvert & Arnedo, 2021 – Hawaii T. ceylonicum Dunlop & Jekel, 2009 – Sri Lanka T. chacoense Levi, 1963 – Bolivia T. chakinuense Wunderlich, 1995 – Turkmenistan T. chamberlini Caporiacco, 1949 – Kenya T. charitonowi Caporiacco, 1949 – Kenya T. charlati Dierkens, 2016 – French Polynesia (Society Is.: Tahiti) T. cheimatos Gertsch & Archer, 1942 – United States T. cheni Zhu, 1998 – China T. chenzhangfui Lin & Li, 2024 – China T. chihuahua Levi, 1959 – Mexico T. chiriqui Levi, 1959 – Panama T. choroni Levi, 1963 – Venezuela T. cinctipes Banks, 1898 – United States, Mexico T. cinereum Thorell, 1875 – Switzerland and Italy to Ukraine and Turkey, Caucasus, Russia, (Europe), Iran T. circuitum Gao & Li, 2014 – China T. circumtextum Simon, 1907 – Guinea-Bissau T. climacode Thorell, 1898 – Myanmar T. clivalum Zhu, 1998 – China T. cloxum Roberts, 1983 – Seychelles (Aldabra) T. clypeatellum Tullgren, 1910 – Ethiopia, Kenya, Tanzania T. cochise Levi, 1963 – United States T. cochrum Levi, 1963 – Brazil T. cocosense Strand, 1906 – Costa Rica (Cocos Is.) T. coenosum Thorell, 1887 – Myanmar T. cohni Levi, 1963 – Brazil T. coldeniae Baert & Maelfait, 1986 – Galapagos T. comstocki Berland, 1920 – Kenya T. confusum O. Pickard-Cambridge, 1885 – Pakistan T. contreras Levi, 1959 – Mexico T. convexellum Roewer, 1942 – Australia (Queensland, New South Wales) T. convexisternum Caporiacco, 1949 – Kenya T. corcyraeum Brignoli, 1984 – Greece (Corfu, Crete) T. costaricaense Levi, 1963 – Costa Rica to Venezuela T. cowlesae Levi, 1957 – United States T. coyoacan Levi, 1959 – Mexico T. cruciferum Urquhart, 1886 – New Zealand T. crucum Levi, 1959 – Mexico T. cuspulatum Schmidt & Krause, 1998 – Cape Verde T. cuyutlan Levi, 1963 – Mexico T. cygneum Gao & Li, 2014 – China T. cynicum Gertsch & Mulaik, 1936 – United States, Mexico T. cyprusense Wunderlich, 2011 – Cyprus, Iran T. dafnense Levy & Amitai, 1982 – Israel