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Species Allocyclosa bifurca

Unusual Spider - Allocyclosa bifurca Allocyclosa bifurca - female Spider with egg sac stabilimenta - Allocyclosa bifurca 70107 - Allocyclosa bifurca Allocyclosa(?) - Allocyclosa bifurca Elevator Spider - Allocyclosa bifurca Elevator Spider - Allocyclosa bifurca What spider please . . - Allocyclosa bifurca
Classification
Kingdom Animalia (Animals)
Phylum Arthropoda (Arthropods)
Subphylum Chelicerata (Chelicerates)
Class Arachnida (Arachnids)
Order Araneae (Spiders)
Infraorder Araneomorphae (True Spiders)
No Taxon (Entelegynes )
Family Araneidae (Orb Weavers)
Genus Allocyclosa
Species bifurca (Allocyclosa bifurca)
Synonyms and other taxonomic changes
Cyclosa bifurca
Explanation of Names
bifurca is Latin for "two-forked", and refers to the forked abdomen.
Size
Female body length ranges from 5.1 to 8.5mm according to Levi.(1)
Male body length is much smaller; only about 35% of the female's. This usually equates to around 2-3mm.
Identification
Abdomen is posteriorly vertically biforked in both males and females, meaning the end of the abdomen has two humps like the letter 'M'.
Live specimens and/or ones not placed in preserving fluid are a very pretty transparent green color (so are the egg sacs).
Females have a red area on their underside between their epigynum and their spinnerets.
The female genitalia are reduced, reverting almost to a haplogynous condition: there is no scape and no ventral opening.(2)
In males, the paramedian apophysis is lacking and the conductor is small.(2)

Please consult Levi's 1977(2) & 1999(1) publications for more details, as well as any older publications under Cyclosa bifurca.
Range
Texas & Florida
(areas outside of the United States include Baja California to Panama and also the W. Indies)(1)
Habitat
Has been collected in the United States under eaves of buildings and in date palms. For new submissions, please use the 'remarks' box to share where you found your specimen.
Remarks
As its family name suggests, this spider creates the classic, round "orb" web that most people associate with spiders.
The orb web is about 6-8 inches in diameter. A wonderful example of one is seen on page 66, plate 5 of (2).
The males of this species are very uncommon. In fact, of about 350 spiders of this species that were examined, only two were male! In 1977, Levi even posed the question, "Is the species parthenogenetic?"(2) Besides the very slim occurance of males, he was also referring to the altered genitalia of this species, which is mentioned above under "Identification".
This orbweaver does an interesting thing in its web, which is rightfully referred to as protective mimicry. The egg sacs are attached to the web in a straight up vertical row and act as a sort of stabilimenta. And the discarded prey carcasses are kept the same way, except in a row straight down. The females perch in the center of the web in between the egg sacs and the carcasses and are difficult to make out since the spider and the egg sacs are both green and also similarly shaped.
Here are a couple of good examples:

As you can see, above the spider is a line of egg sacs while below the spider is a line of wrapped prey. Can you even see the spider??
See Also
There are remarkable similarities with Cyrtophora species. The biforked tail and humps, not found in other araneids, may be synapomorphies with similar structures in Cyrtophora (Levi, 1997, fig. 152).(1)
Print References
Bulletin Museum of Comparative Zoology, Vol. 155, No. 7, p. 304-306(1)
Bulletin Museum of Comparative Zoology, Vol. 148, No. 3, p. 64, 66(2)
Spiders of North America: an identification manual(3) has a small diagram, but not much info, on page 70.
Tip: when researching this species, remember to check for its synonyms like Cyclosa bifurca if you can't find Allocyclosa bifurca, as it's a newer genus and may be referred to as something else in older books.
Works Cited
1.The neotropical and Mexican orb weavers of the genera Cyclosa and Allocyclosa (Araneae, Araneidae)
Herbert W. Levi. Bulletin of the Museum of Comparative Zoology, Harvard University, Vol. 155, No. 7 Cambridge, Mass., May 25, 1999.
2.The American orb-weaver genera Cyclosa, Metazygia, and Eustala north of Mexico (Araneae, Araneidae)
Herbert W. Levi. 1977. Bulletin of the Museum of Comparative Zoology, Harvard University, Vol. 148(3), 61-127.
3.Spiders of North America: An Identification Manual
D. Ubick, P. Paquin, P.E. Cushing and V. Roth (eds). 2005. American Arachnological Society.