Trapdoor Spiders in North America

BugsInTheNews is a VIEWER-PARTICIPANT WEBSITE. This article by Jerry Cates, first published on 13 January 2011, was revised last on 9 January 2013. © Bugsinthenews Vol. 12:01(05)

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Cyrtaucheniidae (Eucteniza spp.): Wafer Trapdoor Spider; lateral view of spider in grass; Stacey, Austin TX--01.09.2011

001. Lateral habitus

Presently, sixteen families are recognized within the infraorder Mygalomorphae. Many are fossorial (adapted to digging and life underground) trapdoor spiders.

The names attached to these families are imposing, and difficult to pronounce. If you take the time to delve into the etymology of these names, you will find a rich history. For example, the name Cyrtaucheniidae (pronounced sir-tawk-en-EE-uh-dee), of the superfamily Cyrtauchenioidea is — as all good taxonomical names might wish to be — based on first impressions of the organisms to which it refers.

A similar name, cyrtocephalus, was first described by the French entomologist Hippolyte Lucas (1814 – 1899),  in 1843 for a genus of trapdoor spiders now placed under the Cyrtaucheniidae family.

That early generic name was replaced by cyrtauchenius in 1869 by the Swedish arachnologist Tord Tamerian Teodor Thorell (1830 – 1901), and the family name Cyrtaucheniidae was assigned by the French arachnologist Eugène Simon (1848 – 1924) in 1892.

Each of these derives from the conjunction of the  Greek adjective κυρτóς, kurtos, meaning “arched, bent, swollen”, and the Greek noun αυχην, auchen, meaning “neck, throat,” to produce the meaning “with arched neck.”

This is said to be a reference to the generally observed fact (viz. the photo at the head of this article) that the pars cephalica of these spiders is highly elevated above the pars thoracica of the cephalothorax.

The enlargement of the uppermost photo shows that, in fact, the “neck” of the specimen from Austin does have the appearance of being arched, and bent upward, so that the eyes of the spider seem, at first glance, to be facing upward as well.

Mygalomorph Spider: Marvin W., Kempner, TX--11.12.08: eyes, dorsal view

002. Eyes, dorsal view

Mygalomorph Spider: Marvin W., Kempner, TX--11.12.08: eyes, frontal view

003. Eyes, frontal view

This is partly an illusion, as photos of another, similar trapdoor spider found in Kempner, Texas, show.

But the illusion is compelling, and helps explain why the appellation was used in reference to these spiders.

The following posts on bugsinthenews.info feature spiders in the infraorder Mygalomorphae:

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Taxonomy:

  • Kingdom Animalia (an-uh-MAYHL-yuh) — first described in 1758 by the Swedish taxonomist Carolus Linnaeus (1707 – 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 (1762 – 1833), using the two Greek roots αρθρον (AR-thron) = jointed + ποδ (pawd) = foot, in an obvious reference to animals with jointed feet, but in the more narrow context of the invertebrates, which have segmented bodies as well as jointed appendages;
  • Subphylum Chelicerata (Kuh-liss-uh-RAH-tah) — first described in 1901 by the German zoologist Richard Heymons (1867 – 1943) using the Greek noun χηλη (KEY-lay) = a claw, talon, or hoof + the Greek noun κερας (SAIR-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 (1769 – 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 – 1765), who used the Latin word aranea = a spider or a spider’s web, to refer to eight legged arthropods that spin webs;
  • Suborder Opisthothelae (oh-PIS-thoh-THEE-lee) — first described in 1990 by the American arachnologists Richard C. Brusca and Gary J. Brusca, who used the Greek words οπισθεν (oh-PIS-thehn) = behind, at the back, yet to come + θηλη (THEE-lee) = nipple or teat, to distinguish this grouping of spiders from the more primitive spiders in the suborder Mesothelae, in that certain characters (e.g., tergite plates, ganglia in the abdomen, and — in particular, inasmuch as the suborder name is a direct reference thereto — median-positioned spinnerets) of the latter are absent in the former; thus spiders in this suborder have spinnerets positioned at the hindmost portion of the abdomen;
  • Infraorder Mygalomorphae (my-GAL-oh-MOHR-fee) — spiders with paraxial chelicerae and two pairs of book lungs, as in the more primitive Mesothelae, but without the latter’s tergite plates and most of the latter’s abdominal ganglia, and having their spinnerets positioned at the abdomen’s hindmost portion rather than mid-ventrally as in the Mesothelae; presently comprised of fifteen families:
    • Atypidae (Thorell 1870) — 3 genera, 49 species (Platnick WSCv13.5); commonly known as purseweb spiders; 8-27 mm, yellow-brown to dark purple-black in color; the legs of male specimens of Sphodros rufipes (Latrielle 1829) and S. fitchi (Gertsch & Platnick 1980) are bright orange-red;
    • Antrodiaetidae (Gertsch 1940) — 2 genera, 33 species (Platnick WSCv13.5); commonly known as foldingdoor, collardoor, or turret spiders (Antrodiaetus), and trapdoor spiders (Aliatypus); 6-26 mm, tan to chestnut brown, with one or more tergites on the anterodorsal abdomen; live in burrows with a flexible collar, a rigid turret, or a trapdoor at the mouth;
    • Mecicobothriidae (Holmberg 1882) — 4 genera, 9 species (Platnick WSCv13.5); no common name; mygalomorphs with two tergites on their anterodorsal abdomen (these sclerotized patches may be fused); build sheet webs with silk tubes from sheet to ground that lead into hiding places under terrestrial objects;
    • Hexathelidae (Simon 1892) — 12 genera, 112 species (Platnick WSCv13.5);
    • Dipluridae (Simon 1889) — 24 genera, 179 species (Platnick WSCv13.5); commonly known as mygalomorph funnelweb spiders; 3.5-17 mm, pale tan to purple-brown in color; thoracic furrow in the form of a short longitudinal groove or a shallow pit or rounded depression;
    • Cyrtaucheniidae (Simon 1889) — 10 genera, 102 species (Platnick WSCv13.5);
    • Ctenizidae (Thorell 1887) — 9 genera, 128 species (Platnick WSCv13.5); no common name; 10-30 mm or more in length, tan, dark chestnut brown, and black in color; the females lack scopulae, but are equipped with a number of robust lateral digging spines on their pedipalps, as well as on the tarsus, metatarsus, and tibia of legs I and II; carapace generally glabrous, with few distinct spines; thoracic furrow is transverse, typically very deep and procurved; burrows are covered with a thick cork-type trapdoor for all genera, except Cyclosmia Ausserer 1871, which have wafer-type trapdoors;
    • Euctenizidae (Raven 1985) — 7 genera, 33 species (Platnick WSCv13.5);
    • Idiopidae (Simon 1889) — 22 genera, 314 species (Platnick WSCv13.5);
    • Actinopodidae (Simon 1892) — 3 genera, 40 species (Platnick WSCv13.5);
    • Migidae (Simon 1889) — 10 genera, 91 species (Platnick WSCv13.5);
    • Nemesiidae (Simon 1889) — 43 genera, 364 species (Platnick WSCv13.5); 16-30 mm, golden brown to dark gray, generally concolorous but sometimes with an indistinct chevron pattern on the dorsal abdomen;
    • Microstigmatidae (Roewer 1942) — 7 genera, 16 species (Platnick WSCv13.5);
    • Barychelidae (Simon 1889) — 44 genera, 307 species (Platnick WSCv13.5);
    • Theraphosidae (Thorell 1869) — 124 genera, 946 species (Platnick WSCv13.5);
    • Paratropididae (Simon 1889) — 4 genera, 8 species (Platnick WSCv13.5);

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References:

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