Rugathodes sexpunctatus
| Rugathodes sexpunctatus | |
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| R. sexpunctatus female | |
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| Species: | R. sexpunctatus
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| Binomial name | |
| Rugathodes sexpunctatus | |
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Theridion sexpunctatum | |
Rugathodes sexpunctatus is a minute species of spider in the family Theridiidae, the cobweb or tangle-web spiders. This family includes the medically important Latrodectus genus--the widow spiders. The species in the Rugathodes genus are too small to be dangerous to humans. There is very little known about any species in this genus.
Description
Total length (of body, excluding legs) is 1.5-2.5 mm. [1][2] Typically, the cephalothorax is pale yellow-brown with a dark/blackish median band, usually extending the full length of the carapace, widest at the posterior eye row, surrounding the eyes. The cephalothorax margins are dusky. The abdomen is pale yellow-brown with a variable pattern of three pairs of black and white spots, giving the species its name (from the Latin sex meaning "six" and punctum meaning "spot"). There is often a broken white band bordering the rows of spots. The sides of the abdomen are dusky and the ventral surface is pale. There is considerable variation within the species, with east coast specimens tending to have distinct spots, while west coast specimens can have a totally black abdominal dorsum. Alaska specimens tend to be intermediate in coloration[1], but are variable, with overall coloration from the typical pale yellow-brown to dark brown or greenish-gray, and occasionally pinkish areas on the dorsum between the spots. Darker individuals can be very difficult to diferentiate from the closely related Rugathodes aurantius.
Female distinguishing characteristics: The paired openings of the epigynum (epigyne) are nearly merged into a single oval opening, with a variable median divider extending in from the anterior side, giving the impression of a rounded ‘B’ laying on its back.
Male distinguishing characteristics: The chelicerae (fangs) are enlarged with a very distinctive shape.[1][2]
Distribution
This species is widespread across the United States, southern Canada and Russia.[1][3] In North America, it has been reported from the far Aleutians (Kanaga Island) to Newfoundland, south to central California, northern Arizona, North Carolina. It is usually found in conifers.[1]
References
- ^ a b c d e Levi, Herbert W. (1957). The spider genera Enoplognatha, Theridion, and Paidisca in America north of Mexico (Araneae, Theridiidae). Bulletin of the American Museum of Natural History 112(1). pp 91-97, 119 [1]
- ^ a b Kaston, B.J. (1976). Supplement to the Spiders of Connecticut. Journal of Arachnology, Vol. 4. No. 1. pg 16. [2]
- ^ Platnick, Norman I. (2009): The world spider catalog, version 9.5. American Museum of Natural History.
- Paquin, Pierre, Nadine Dupérré. 2003. Guide d'identification des Araignées (Araneae) du Québec. Fabreries, Supplément 11. Association des entomologistes amateurs du Québec. pg 220.