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Southern Black Widow
Male
(Latrodectus
mactans) Photography and text by Jerry Cates
This male was found in a smaller web less than fifteen feet from the female. It is not unusual for males of this species to prepare and maintain separate webs, though the males will also cohabit the webs of females. This specimen has the exterior coloration typical for males of the species, but such coloration is quite variable. Note the string of spots down the centerline of the dorsal abdomen, and the whitish lateral markings on the abdomen sides. Underneath, the sternum (the plate covering the ventral surface of the carapace) is completely black, while the ventral abdomen is marked with a large, reddish orange hourglass. The legs, though mostly black, have intermittent tan sections that appear to follow a somewhat regular pattern.
The hairs on the body of the male are more conspicuous, though they remain sparse in comparison with those of most spiders.
The photo below provides a dorsal view of the male black widow's eyes, showing the PME (center), the structure containing the AME, and the lateral structure containing the right-side PLE and ALE.
A dorsal view of the spider's pedipalps is shown below. These structures are quite different in the male. In the female the pedipalps appear as diminutive legs, but in the male of this species they are grossly enlarged at their distal ends. The male palp is used to transfer sperm to the female's epigynum during copulation. Its unique architecture, for a given species, assists in making precise identifications. Though such specificity suggests a means whereby cross-breeding between species is discouraged or prevented, strong evidence for that is lacking. Apparently, cross-breeding is unlikely, not because of the architecture the copulatory organs, but more as a consequence of unique courting rituals.
A ventral view of the male pedipalps shows some details of their gross external features. The spiral structure in each palp is the embolus, which forms a long, spiral thread whose length can be several times that of the male's body. It is not unusual for an embolus to break during copulation, and to be left behind when copulation is complete. Apparently, though such artifacts may remain in the epigynum for lengthy periods, they do not necessarily interfere with future mating.
Go to Southern Black Widow FEMALE Macroscopy... ---------------------------------------------- The black widow spider is venomous, and its bite should be treated immediately at a medical clinic. We would like to hear of your experiences with such bites. We are also investigating the risk of secondary infections that may occur as a result of bites from other, otherwise harmless spiders whose venom is known to pose little or no danger to humans. In the process, we are collecting information on experiences persons have had with such spider bites. Please contact us about your personal experiences, if you have been bitten by this or any other spider, including jumping spiders and garden spiders (the bites of which typically produce a transitory inflammation, but resolve within a few days without medical attention), whether recently or in the past thirty years, anywhere in the world. For example, the bite of a species of garden spider, the golden orb spider of Australia [Nephila edulis] typically is unremarkable, but on occasion produces medically significant secondary infections; the frequency and nature of bites experienced from that species of spider is also a part of this study. The object of this study is to collect data that might relate to a mysterious series of spider-related infections, involving a special pathogen, that took place in the United States and in Australia between 1977 and 2006. Although only fifteen such infections were reported to medical establishments, seven appear to be associated with spider bites. Some authorities suggest that the number of actual infections of this type that occurred in the U.S. and Australia during the past thirty years is much larger, but that they have been underreported. Underreporting of specific kinds of infections can occur, either because the persons infected chose not to seek medical assistance, or the medical establishments misdiagnosed the infections as being caused by other infectious agents. We are seeking to establish an estimate of the number of human spider bites that occur each year by these and similar spiders, whether the bite resulted in injury to the human or not. Next, we hope to establish the number of instances where the bite (1) became inflamed and/or infected, then resolved without medical intervention, or (2) infected, ulcerated, or led to a generalized sickness, and required medical intervention. ---------------------------------------------- Back to: Texas Spiders Back to: Bugsinthenews |
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