Identification of Latrodectus mactans - Southern Black Widow

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Home » Guide » Arthropods (Arthropoda) » Chelicerates (Chelicerata) » Arachnids (Arachnida) » Spiders (Araneae) » True Spiders (Araneomorphae) » Entelegynae » Cobweb Spiders (Theridiidae) » Widow Spiders (Latrodectus) » Southern Black Widow (Latrodectus mactans)
Species Latrodectus mactans - Southern Black Widow
Classification · Other Common Names · Pronunciation · Synonyms and other taxonomic changes · Explanation of Names · Size · Identification · Range · Habitat · Food · Life Cycle · Remarks · See Also · Internet References · Works Cited
Female with egg sac - Latrodectus mactans - female black widow spiderlings - Latrodectus mactans Cool small spider - Latrodectus mactans Southern Black Widow - Latrodectus mactans Pair of black widows - Latrodectus mactans - male - female Spider ID - Latrodectus mactans Southern Black Widow - Latrodectus mactans - female Latrodectus mactans - female
Classification
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)
Genus Latrodectus (Widow Spiders)
Species mactans (Southern Black Widow)
Other Common Names
Black Widow - The L. mactans is often considered the original "Black Widow".
“The Hourglass Spider” because of the red hourglass shaped mark on the female’s abdomen.
“The Shoe Button Spider” due to the form of the spider’s jet-black abdomen.
Pronunciation
lat"ro-dek't[schwa]s mac'·tans
Synonyms and other taxonomic changes
See the World Spider Catalog.
Explanation of Names
See the Latrodectus guide page for the etymology of Latrodectus.
Size
Adult Female:
Approximately 8-13 mm (~1/2 inch) in body length.
With legs extended, the female measures about 25-35 mm (1 inch - 1 1/2 inches).

Adult Male:
Approximately half the size of the female, around 4-6 mm (1/4 inch) in body length.
With legs extended, the male measures 12-18 mm (1/2 inch - 2/3 inch).
See this picture for side-by-side view:
Identification
The southern black widow is one of the most common of the native widow spiders. It is the epitome of the classic widow spider, occurring in all the normal widow spider habitats.

Female: The adult female black widow spider has a glossy jet black color all over, including body and legs. The only red marks are the bright red hourglass mark on the underside of the abdomen, and a red spot just behind and above the spinnerets. The hourglass marking consists of two connected red triangles on the underside. Note, however, that the hourglass color may range from yellowish to various shades of orange or red. If the hourglass marking is not connected (e.g. - two distinct, non-touching triangles), it is most likely the northern cousin (L. variolus) of the southern black widow (L. mactans)

Males: Adult males are harmless, is 3-5 mm long with an elongated abdomen. The male’s legs are larger than the female’s and each leg segment is orange brown in the middle and black on the ends. On the sides of the male’s abdomen there are four pairs of red and white stripes. (Net Ref (3))

Immatures: Newly hatched spiderlings are predominately white or yellowish-white, gradually acquiring more black and varying amounts of red and white with each molt. Juveniles of both sexes resemble the male and are harmless. (Net Ref (1))

(Id info from bugguide.net)

Posted on Δεκέμβριος 21, 2023 0721 ΜΜ by cs16-levi