Identification, Images, & Information
For Insects, Spiders & Their Kin
For the United States & Canada
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putative Cobweb Spider Egg Sac Is it Neospintharus? Spider with cone shaped abdomen Some Argyrodes elevatus and some not sure.   Small spider found on  Argiope aurantia web. Silver-butted Spider 6/3/2023 insect egg case tiny spider found feeding on Joro
Kingdom Animalia (Animals)
Phylum Arthropoda (Arthropods)
Subphylum Chelicerata (Chelicerates)
Class Arachnida (Arachnids)
Order Araneae (Spiders)
Infraorder Araneomorphae (True Spiders)
No Taxon (Entelegynae)
Family Theridiidae (Cobweb Spiders)
No Taxon Argyrodes/Faiditus/Neospintharus/Rhomphaea
Synonyms and other taxonomic changes
Argyrodes - 5 (N.A.)
Faiditus - 8 (N.A.)
Neospintharus - 3 (N.A.)
Rhomphaea - 2 (N.A)
Argyrodes - 5 (N.A.)- 3 species in bugguide's range. (argentatus & hawaiiensis found in Hawaii.)
- elevatus - Virginia to Texas and Missouri
- nephilae - peninsular Florida
- pluto - Maryland, Virginia, Missouri, and Texas
Faiditus - 8 (N.A.)
- americanus - Florida, South Mississippi, South Texas
- cancellatus - eastern USA & Canada
- caudatus - South Florida, South Texas
- davisi - South Texas - carapace grayish brown yellow anteriorly with a pair of brown longitudinal lines behind the eyes and a pair of transverse markings connected to lines. Anterior legs yellowish proximally, becoming dark brown toward ends of femora, other segments dark. Posterior legs yellow with faint reddish brown annulations.
- dracus - Alabama
- globosus - Atlantic and Gulf Coasts, South Carolina to Southeast Texas
- maculosus - Central Florida
- subdolus - Texas, Arizona
Neospintharus - 3 (N.A.)
- baboquivari - Arizona
- furcatus - South Carolina to Texas (and south California?)
- trigonum - eastern USA & Canada
Rhomphaea - 2 (N.A)
- projiciens - South Florida and South Texas
- fictilium - eastern USA, West Coast, & Canada
Species found in Texas (Levi, 1962)
Rhomphaea fictilium - eastern TX
Rhomphaea projiciens - south central TX
Neospintharus trigonum - very eastern border of TX
Neospintharus furcatus - eastern half of TX
Argyrodes elevatus - eastern half of TX
Argyrodes pluto - central, southern TX
Faiditus americanus - southern tip of TX
Faiditus globosus - very eastern border of TX
Faiditus caudatus - very southern tip of TX
Faiditus cancellatus - eastern TX
Faiditus davisi - very southern tip of TX
Faiditus subdolus - central & southern TX
This page contains images of spiders that are representatives of the four genera listed above (=subfamily Argyrodinae), but cannot yet be placed to a specific genus level.

From the following PDF:
Morphological phylogeny of cobweb spiders and their relatives (Araneae, Araneoidea, Theridiidae), INGI AGNARSSON*

The cobweb spiders, family Theridiidae, constitute one of the largest spider families, with over 2300 species in 79 genera distributed worldwide.

..Also, no other family includes as many kleptoparasites. Kleptoparasitic spiders occupy heterospecific webs to steal prey or silk. Argyrodes includes the most famous and conspicuous kleptoparasites, found worldwide in the webs of the largest known orb-weavers, Nephila and numerous other spiders The biology of the members of Argyrodes and their distribution among their host webs are areas of active research. Both sociality and most instances of kleptoparasitism typically entail ‘web sharing’, and the two types of behaviour may be phylogenetically related.

..‘Spiders of the genus Argyrodes (Theridiidae) are generally known as kleptoparasitic’ ‘Some species of Argyrodes (Theridiidae) can regularly be found in the webs of other spiders… Other Argyrode are free-living, some feed on spiders’. It has even been suggested that the expression of behaviour (either kleptoparasitism or free living araneophagy) is environmentally controlled, rather than showing a phylogenetic pattern (see Whitehouse et al., 2002).

...Levi’s synonymies, and continued treating Ariamnes and Rhomphaea (the most distinct nonkleptoparasitic Argyrodinae) as valid genera.

...The problem of explaining kleptoparasitism and araneophagy may lie in the terms themselves. Kleptoparasitism entails many components, one of which can be the consumption of spiders. Invasion of a foreign web is one feature that unites argyrodines (although secondarily lost). Spiders generally take any prey they can handle, and prey choice in those invaded webs was no doubt originally as general, including both items stuck in the web and the web’s host. Many extant species show such generalized behaviour (such as the basal Faiditus chickeringi) whereas others specialize either in eating the host or its prey. Thus, obligatory kleptoparasitism may represent the sppression of araneophagy in order not to kill a host that continues to provide food. Conversely, obligatory araneophagy in Ariamnes and Rhomphaea may represent the suppression of ancestral kletoparasitism.

..All known Faiditus are kleptoparasitic and, as in Argyrodes, males are often larger than females (Exline & Levi, 1962).
Internet References
Agnarsson resurrects Faiditus and Neospintharus