A Rabid Wolf Spider in Southlake, Texas

Rabid Wolf Spider (Rabidosa rabida), female; Dave B.--08.08.2010

Rabid Wolf Spider (Rabidosa rabida); Dave B.--08.08.2010

BugsInTheNews is a viewer-participant website. This article by Jerry Cates and Dave B., first published on 9 August 2010, was last revised on 9 July 2012. © Bugsinthenews Vol. 11:08(05).

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Dave wrote:

Any idea what this big boy is?

The rabid wolf spider (Rabidosa rabida), which is often known by the common name “wolf spider” (though that label is also attached in a general way to describe all the spiders in the family Lycosidae),  is one of our largest wolf spiders.

In the photo at left, the specimen depicted has a body that is a full 1.5 inches in length, with a leg span that approaches four inches.

It should be no surprise  that when these spiders are found they inspire fear and dread.

They are distributed throughout a large portion of the United States, from Maine southward to Florida, thence westward to Texas, and north from there to Nebraska and all the area within the trapezoid those points circumscribe.

The ferocious name notwithstanding, this essentially harmless spider is one of our most beneficial arachnids. A wandering hunter, it preys on insects and other spiders. Though it will bite if handled roughly, its venom is not considered dangerous to humans or to our canine and feline pets. Many arachnophiles keep this species in vivariums, where they are able to thrive on small crickets and other small insects for several years.

According to one particularly authoritative source (Brady & McKinley, 1994) the genus Rabidosa is distinguished from other lycosids by the following combination of characters:

First,  its carapace has a pale yellow to brownish yellow background color, with (except for R. hentzi) a pair of relatively broad, dark brown to black longitudinal stripes that extend from the clypeus to the posterior declivity (where the abdomen attaches to the carapace). Note that the rabid wolf spider depicted in this post has such markings on its carapace (see the photo of the carapace below).

Rabid Wolf Spider (Rabidosa rabida), female; Dave B.--08.08.2010

Rabid Wolf Spider (Rabidosa rabida); Dave B.--08.08.2010

Rabid Wolf Spider (Rabidosa rabida), female; Dave B.--08.08.2010

Rabid Wolf Spider (Rabidosa rabida); Dave B.--08.08.2010

Second,  the dorsal abdomen (again, with the exception of R. hentzi)  has a dark brown median stripe flanked by a lighter yellowish color. In the specimen depicted here, the dorsal abdomen has such markings. Note that the dark brown median stripe is deeply incised at its midpoint, with three pairs of pale spots embedded in the stripe between the midpoint and the posterior extent of the dorsal abdomen. This specific pattern is more or less unique to the rabid wolf spider.

Third, the legs are relatively long in comparison to the body, a characteristic that especially distinguishes this genus from the genera Trochosa, Varacosa, Gladicosa, and most species in the genus Hogna. Clearly this feature is present in the depicted specimen.

Rabid Wolf Spider (Rabidosa rabida), female; Dave B.--08.08.2010

Rabid Wolf Spider (Rabidosa rabida); Dave B.--08.08.2010

Fourth, the legs are absent distinct annulations, or rings. Rings (of contrasting coloration) are not present in this specimen.

Fifth, the palps–which are diminutive, leg-like structures, one on each side of the face, that can be  stretched outward in front of the spider–have two slender, sickle-shaped terminal projections. Neither this or the sixth character, described below, can be confirmed or denied for this specimen, as the necessary microscopic examination of the palps cannot be performed from these photographs.

Sixth, the median projections on the palps have a spur near their bases.

Seventh, the spider does not burrow into the soil, and finally,

Eighth, the spider prefers, as a foraging substrate, a grassy vegetation and/or a small shrub to bare ground or leaf litter. Since the behavior of this spider was not observed by the person who took these photographs, we have no way to confirm or deny this or the preceding character.

Notice the face of this spider, as shown in the last photo in this post. The spider has eight eyes, two of which are so huge that they appear as large, black headlamps. These eyes, though dark when viewed in normal light, have highly reflective retinas. If, on a dry, dark night, with all other lights off, you step into your back yard with a flashlight positioned on the side of the head facing outward, you will notice a myriad of diamonds in the grass reflecting the light from the flashlight back to your eyes. These are wolf spiders, and some are likely rabid wolf spiders of this species.

If you perform this test and see no diamonds in your grass, it is possible that your yard is too toxic for these spiders to survive. Consider avoiding the use of toxic pesticides, so that, over time, lots of spider’s eyes can be seen this way. When you see such a display, be pleased in the knowledge that your yard is healthy.

Many of our spiders are not well known, either to laymen or to arachnologists. Fortunately for us, in the case of the rabid wolf spider much research has been conducted on various aspects of its biology, and the literature is flush with articles on courtship behavior, the effects of various pesticides, predatory organisms, and details regarding certain anatomical and physiological characters.

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Taxonomy:
  • Kingdom Animalia (ahn-uh-MAYHL-yuh) — first described in 1758 by the Swedish taxonomist Carolus Linnaeus [23 May 1707 – 10 January 1778], using the Latin word animal = “a living being,” from the Latin word anima = “vital breath”, to refer to multicellular, eukaryotic organisms whose body plans become fixed during development, some of which undergo additional processes of metamorphosis later in their lives; most of which are motile, and thus exhibit spontaneous and independent movements; and all of whom are heterotrophs that feed by ingesting other organisms or their products; 
  • Phylum Arthropoda (ahr-THROPP-uh-duh) first described in 1829 by the French zoologist Pierre André Latreille [November 20, 1762 – February 6, 1833], using the two Greek roots αρθρον (AR-thron) = jointed + ποδ (pawd) = foot, in an obvious reference toanimals with jointed feet, but in the more narrow context of the invertebrates, which have segmented bodies as well as jointed appendages;
  • Subphylum Chelicerata (Kehl-iss-uh-RAH-tah) — first described in 1901 by the German zoologist Richard Heymons [1867 – 1943] using the Greek noun χηλη (KEY-lee) = a claw, talon, or hoof + the Greek noun κερας (Ser-as) = an animal’s horn + the Latin suffix ata — which by convention is suffixed to the names of animal subdivisions — to refer to animals that have specialized appendages before the mouth that they use in feeding, capturing and securing prey and that — in the case of spiders — are further equipped to inject venom and digestive agents into their prey; 
  • Class Arachnida (uh-RAKH-nuh-duh) first described in 1812 by the French naturalist and zoologist Jean Léopold Nicolas Frédéric Cuvier [August 23, 1769 – May 13, 1832], usually referred to as Georges Cuvier, using the Greek noun αραχης (uh-RAH-kes) = a spider, in reference to all eight-legged arthropods, including such disparate animals as ticks, mites, scorpions, harvestmen, solpugids, and spiders; 
  • Order Araneae (uh-RAY-neh-ee) — first described in 1757 by the Swedish entomologist and arachnologist Carl Alexander Clerck [1709 – 22 July 1765], who used the Latin word aranea = a spider or a spider’s web, to refer to eight legged arthropods that spin webs.;
  • Suborder Araneomorphae (uh-Ray-nee-oh-MOHR-fee) —distinguished from the Mygalomorphae (whose fangs are aligned nearly parallel to one another) by having opposing fangs that that open and close like pincers;
  • Series Entelegynae (inn-Tehl-uh-JYE-nee) — distinguished from the Haplogynae (in which the female epigynum is not sclerotized) by the presence, in the female, of a sclerotized epigynum; most entelegyne spiders have eight eyes, while many haplogynes have less than eight eyes;
  • Superfamily Lycosoidea (Lye-coh-SOY-dee-uh) — araneomorph eight-eyed spiders, comprised of twelve families: (1) Ctenidae, (2) Lycosidae, (3) Neolanidae, (4) Oxyopidae, (5) Pisauridae, (6) Psechridae, (7) Senoculidae, (8) Stiphidiidae, (9) Trechaleidae, (10) Zoridae, (11) Zorocratidae, (12) Zoropsidae;
  • Family Lycosidae (lye-COH-sihd-ee) — first described in 1833 by the Swedish zoologist Carl Jakob Sundevall (1801-1875), using the Greek word λύκος (LYE-cohs) = wolf, a reference to the fact that these spiders are capable wandering hunters that possess unusually good vision; unlike wolves, they are generally solitary spiders that hunt alone; all wolf spiders have eight eyes, with four small, nearly equally-sized anterior eyes arranged in a more or less straight row (the nuanced curvature of the anterior eye row, or AER, is diagnostic of various genera) across the face of the carapace, while the four posterior eyes (all much larger than the anterior eyes) form a quadrangle, wider posteriorly than anteriorly, the lateral eyes (PLE) positioned some distance back on the carapace, and the posterior median eyes (the most prominent of the spiders eight eyes) positioned on the face above the AER; distributed worldwide in 120 genera, 2,388 species (Platnick, 2012), represented in North America by 16 genera, 238 species (Dondale, in Ubick et al., 2005);
  • Genus Rabidosa (rabb-eh-DOH-sah) — first described in 1960 by the German arachnologist Carl Friedrich Roewer (12 October 1881 – 17 June 1963), who, in deference to Walckenaer’s epithet for the type species of this genus (Rabidosa rabida), used the Latin root rabidus = raving mad, savage, raging (Williams, 2005) + the Latin suf. ind. –osus = full of, of full development, abundance (ibid), in reference to the legendary frightful appearance of these robust, fast moving, ferocious-looking spiders; all five recognized species in this genus are native to North America, and all but one, Rabidosa rabida, are confined to the United States; a detailed account of the characters distinguishing these various species is provided in Brady & McKinley, 1944, a link to which is provided in the bibliography below;
  • Species Rabidosa rabida (rabb-eh-DOH-sah RAB-eh-duh) — first described in 1837 by the French arachnologist and civil servant Charles Athanase Walckenaer (1771–1852), who used the Latin root rabidus = raving mad, savage, raging (Williams, 2005) to reference the legendary frightful appearance of these robust, fast moving, ferocious-looking spiders; the species is distinguished from R. hentzi in having an abdomen with a median dorsal longitudinal dark stripe, flanked by a lighter color, and from the other three species of this genus by having a dorsal longitudinal dark stripe on the abdomen enclosing four pairs of white spots posteriorly (Brady & McKinley, 1994); this longitudinal dark striped is deeply incised just anterior to the four white spots, and in the female the first pair of white spots is incompletely enclosed, producing to the attentive eye two pairs of deep incisions anterior to three pairs of fully enclosed spots, while in the male all four pairs of white spots are fully enclosed.

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References:

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