Robertus
O. Pickard-Cambridge, 1879
Robertus is a of -footed in the Theridiidae. It was established by Octavius Pickard-Cambridge in 1879 and is recognized as the senior synonym of the former genus Garritus. The genus comprises small spiders that construct tangled, irregular webs. within Robertus are found primarily in the Northern Hemisphere, with documented occurrences in Europe and North America.
Pronunciation
How to pronounce Robertus: /roʊˈbɛrtəs/
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Identification
Robertus are small theridiid , generally under 5 mm in body length. They can be distinguished from other theridiid by a combination of characters including the arrangement of , the structure of the -like serrated bristles () on the hind , and details of the male and female . The is typically globular or slightly elongated. Accurate identification to species level requires examination of under magnification.
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Habitat
of Robertus inhabit moist, shaded microhabitats including leaf litter, moss, and the underside of stones and logs in forested areas. Some species have been recorded from caves and other subterranean environments. They appear to prefer humid conditions with stable temperatures.
Distribution
Documented from northern Europe (Denmark, Norway, Sweden) and North America (Vermont, United States). The has a Holarctic distribution pattern, though comprehensive regional surveys are limited.
Similar Taxa
- TheridionBoth are small theridiid with globular , but Theridion generally have different arrangements and lack the specific ctenidial structure characteristic of Robertus.
- SteatodaSteatoda are larger, more theridiids with often patterned and more substantial web architecture; Robertus species are smaller and more delicate.
- EnoplognathaEnoplognatha can resemble Robertus in size and preference, but differ in genital and typically show more pronounced abdominal patterning.
More Details
Taxonomic history
The Garritus, described by Simon in 1909, was synonymized with Robertus based on morphological similarities, particularly in genital structure. This synonymy was established to maintain nomenclatural under the principle of priority.
Research needs
The Robertus remains understudied in many regions. boundaries are poorly defined for several , and molecular phylogenetic studies are needed to clarify relationships within the genus and its placement within Theridiidae.