Cobweb Spiders - Family: Theridiidae
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With 2538 species spread over 124 genera in seven subfamilies, the Theridiidae are among the largest of families within the Superfamily: Araneoidea. First described by Carl J. Sundevall, a Swedish zoologist, in 1833 this family is yet another one that has seen many changes over the years with more than a third on its' genera being newly described since 1990. As well as that, a considerable proportion of species has been shunted from genus to genus or from the Theridiidae to other families.
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Many species in this family are small spiders, most of the remainder being no larger than medium sized. Sizes between 3 and 10 mm appear to be most common. They are said to be the most common arthropods encountered by humans in their homes. Theridiid spiders are referred to ecribellate spiders which simply means they do not have a cribellum, a special spinning organ that probuces a wooly kind of silk. Spiders that lack this organ are capable of producing a silk that is very sticky and renders the silk more efficient at holding prey once caught.
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Cobweb Spiders are also known as Tangle-web Spiders in reference to the type of webs they build and also, as Comb-footed Spiders. This name refers to the comb-like structure made up of serrated bristles (= setae) that is located on the last segment (= tarsus) of their hindmost legs. With the tip of the hindlegs they draw out filaments of silk from all the tiny spigots and 'comb' these to ensure the filaments form a single thread that can be used for web building or to wrap up the prey.
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Within the Theridiidae there are a handful of spiders that are referred to as 'model organisms' for research. (A species of plant, animal or other life form that is studied for a particular purpose.) The Widow Spiders f.i. from the subfamily: Latrodectinae - which includes our Redback Spider - are studied to find out more about the venom they produce. Also, spiders of the genus: Anelosimus are helping scientist to understand social behaviours in animals.
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Some genera in the subfamily: Argyrodinae are referred to as 'kleptoparasites'. These little spiders move in with other, often larger, spiders in their web and they steal small prey that is caught within the web before the host spider can get to it. This 'thieving' behaviour is innate in quite a few animals but it can also be learned. Sperm Whales for instance, have become quite adept at stealing caught fish off longlines set by fishermen.
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Subfamily: Anelosiminae
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Subfamily: Argyrodinae
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Alanna's Thief Spider - Argyrodes alannae
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Australian Dewdrop Spider - Argyrodes antipodianus
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Argyrodes binotata (possible occurrence)
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Thief Spider - Argyrodes fissifrons
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Argyrodes incissifrons (possible occurrence)
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Red-spotted Argyrodes - Argyrodes incursus
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Argyrodes margaritarius
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Small Thief Spider - Argyrodes miniaceus
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Argyrodes rainbowi
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Whip Spider - Ariamnes colubrines
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Rhomphaea cometes (likely occurrence)
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Subfamily: Hadrotarsinae
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Dipoena austera (possible occurrence)
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Dipoena setosa (possible occurrence)
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Elegant Ant-eater Spider - Euryopis elegans
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Euryopis multipunctata (possible occurrence)
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Splendid Tick Spider - Euryopis splendens
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Euryopis superba (likely occurrence)
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Superb Ant-eater Spider - Euryopis umbilicata
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Gmogala scarabaeus (possible occurrence)
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Subfamily: Latrodectinae
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Crustulina guttata (possible occurrence)
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Brown Widow - Latrodectus geometricus (likely occurrence)
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Redback Spider - Latrodectus hasselti
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Black Cobweb Spider - Steotoda capensis
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False Black Widow - Steotoda grossa
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Steotoda nasata
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Steotoda truncata
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Subfamily: Pholcommatinae
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Magnapholcomma globulus
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Magnapholcomma sp. novum ?
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Round Shell-back Spider - Phoroncidia rotunda (possible occurrence)
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Six-humped Shell-back Spider - Phoroncidia sextuberculata
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Three-humped Shell-back Spider - Phoroncidia trituberculata (possible occurrence)
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Subfamily: Spintharinae
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Two-horned Episinus - Janula bicornis
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Southern Moneta - Moneta australis
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Silver Dewdrop Spider - Thwaitesia argentiopunctata
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Black-spotted Thwaitesia - Thwaitesia nigrodonosa
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Subfamily: Theridiinae
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Archaearanea propera (possible occurrence)
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Chrysso spp.
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White Porch Spider - Cryptachaea gigantipes
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Diamond Comb-footed Spider - Cryptachaea veruculata
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Meotipa pulcherrima (possible occurrence)
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Red House Spider - Nesticodes rufipes
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Common House Spider - Parasteatoda tepidariorium
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Platnickina sp.
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Theridion convexellum (possible occurrence)
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Theridion gibbum
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Theridion limitatum
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Pyramidal Theridion - Theridion pyramidale
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Theridion theridioides
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Ladybird Spider - Theridula gonygaster
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Taxonomy:
Phylum: Arthropoda (Arthropods)
> Subphylum: Chelicerata (Chelicerates)
> Class: Arachnida (Arachnids)
> Order: Aranea (Spiders)
> Suborder: Araneomorphae (Typical Spiders)
> Infraorder: Entelegynea (Entelegyne Spiders)
> Superfamily: Araneoidea (Araneoid Spiders)
> Family: Theridiidae (Cobweb Spiders)
> Subfamily: Anelosiminae
> Genus: Anelosimus
> Species: A. pratchetti - Terry Pratchet's Anelosimus
> Subfamily: Argyrodinae (Kleptoparasitic Spiders)
> Genus: Argyrodes (Dewdrop Spiders)
> Species: A. alannae - Alanna's Thief Spider
> Species: A. antipodianus - Australian Dewdrop Spider
> Species: A. binotata ^
> Species: A. fissifrons - Thief Spider
> Species: A. incissifrons ^
> Species: A. incursus - Red-spotted Argyrodes
> Species: A. margaritarius
> Species: A. miniaceus - Small Thief Spider > Species: A. rainbowi
> Genus: Ariamnes (Whip Spiders)
> Species: A. colubrinus - Whip Spider
> Genus: Rhomphaea (Stretched Thief Spiders)
> Species: R. cometes *
> Subfamily: Hadrotarsinae
> Genus: Dipoena
> Species: D. austera ^
> Species: D. setosa ^
> Genus: Euryopis (Ant-eating Spiders)
> Species: E. elegans - Elegant Ant-eater Spider
> Species: E. multipunctata ^
> Species: E. splendens - Splendid Tick Spider
> Species: E. superba *
> Species: E. umbilicata - Superb Ant-eater Spider
> Genus: Gmogala
> Species: G. scarabaeus ^
> Subfamily: Latrodectinae
> Genus: Crustulina #
> Species: C. guttata ^
> Genus: Latrodectus (Widow Spiders)
> Species: L. geometricus - Brown Widow *
> Species: L. hasselti - Redback Spider
> Genus: Steatoda (False Widow Spiders)
> Species: S. capensis - Black Cobweb Spider
> Species: S. grossa - False Black Widow
> Species: S. nasata
> Species: S. truncata
> Subfamily: Pholcommatinae
> Genus: Magnopholcomma
> Species: M. globulus
> Species: sp. novum ?
> Genus: Phoroncidia (Mushroom Comb-footed Spiders)
> Species: P. rotunda - Round Shell-back Spider ^
> Species: P. sextuberculata - Six-humped Shell-back Spider
> Species: P. trituberculata - Three-humped Shell-back Spider ^
> Subfamily: Spintharinae
> Genus: Janula
> Species: J. bicornis - Two-horned Episinus
> Genus: Moneta
> Species: M. australis - Southern Moneta
> Genus: Thwaitesia (Mirror-ball Spiders)
> Species: T. argentiopunctata - Silver Dewdrop Spider
> Species: T. nigrodonosa - Black-spotted Thwaitesia
> Subfamily: Theridiinae
> Genus: Achaearanea
> Species: A. propera ^
> Genus: Chrysso
> Species: Various unidentified species
> Genus: Cryptachaea
> Species: C. gigantipes - White Porch Spider
> Species: C. veruculata - Diamond Comb-footed Spider
> Genus: Meotipa
> Species: M. pulcherrima ^
> Genus: Nesticodes
> Species: N. rufipes - Red House Spider
> Genus: Parasteatoda (Colourful Comb-footed Spiders)
> Species: P. tepidariorum - Common House Spider
> Genus: Platnickina
> Species: ?
> Genus: Theridion (Typical Cobweb Spiders)
> Species: T. convexellum ^
> Species: T. gibbum
> Species: T. limitatum
> Species: T. pyramidale - Pyramidal Theridion
> Species: T. theridioides
> Genus: Theridula
> Species: T. gonygaster - Ladybird Spider
> Species: ? ##
* = likely
^ = possibly
# = There are two possible candidates for the sightings of Crustulina sp. One is C. guttata and the other is C. scabripes All sightings on iNaturalist appear to be of the same species and from the descriptions in Lucas, H. (1846) and Wider, F. (1834) it would appear that C. guttata may be the one. Note: older synonyms were in use at the time of Lucas and Wider.
## = sightings of Theridula spp. are of individuals with and without spikes on the abdomen. It is possible that the spikes are found only on mature females of the species and therefore the sightings recorded on iNaturalist may all be of T. gonygaster.
References and links:
> Keyserling, E., (1890). Die Arachniden Australiens, nach der Natur beschrieben und abgebildet. Zweiter Theil (Lieferung 37). Bauer & Raspe, Nürnberg, 233-274, pl. 21-24. doi:10.5962/bhl.title.121660
> Lucas, H., (1846). 'Histoire naturelle des animaux articulés. In: Exploration scientifique de l'Algérie pendant les années 1840, 1841, 1842 publiée par ordre du Gouvernement et avec le concours d'une commission académique.' Paris, Sciences physiques, Zoologie 1, 89-271, pl. 1-17. doi:10.5962/bhl.title.112444
> Wider, F., (1834). 'Arachniden.' in: Reuss, A., (ed.) 'Zoologische miscellen.' Museum Senckenbergianum, Abhandlungen aus dem Gebiete der beschreibenden Naturgeschichte 1, 195-276.
https://www.treehugger.com/kleptoparasites-animals-steal-food-others-4869227
https://en.wikipedia.org/wiki/Carl_Jakob_Sundevall
https://en.wikipedia.org/wiki/Cribellum
https://en.wikipedia.org/wiki/Model_organism
https://en.wikipedia.org/wiki/Theridiidae
https://en.wikipedia.org/wiki/Theridion
> Keyserling, E., (1890). Die Arachniden Australiens, nach der Natur beschrieben und abgebildet. Zweiter Theil (Lieferung 37). Bauer & Raspe, Nürnberg, 233-274, pl. 21-24. doi:10.5962/bhl.title.121660
> Lucas, H., (1846). 'Histoire naturelle des animaux articulés. In: Exploration scientifique de l'Algérie pendant les années 1840, 1841, 1842 publiée par ordre du Gouvernement et avec le concours d'une commission académique.' Paris, Sciences physiques, Zoologie 1, 89-271, pl. 1-17. doi:10.5962/bhl.title.112444
> Wider, F., (1834). 'Arachniden.' in: Reuss, A., (ed.) 'Zoologische miscellen.' Museum Senckenbergianum, Abhandlungen aus dem Gebiete der beschreibenden Naturgeschichte 1, 195-276.
https://www.treehugger.com/kleptoparasites-animals-steal-food-others-4869227
https://en.wikipedia.org/wiki/Carl_Jakob_Sundevall
https://en.wikipedia.org/wiki/Cribellum
https://en.wikipedia.org/wiki/Model_organism
https://en.wikipedia.org/wiki/Theridiidae
https://en.wikipedia.org/wiki/Theridion
Photographic contributions: