What does the term 'labidognathous' describe?

What does the term 'labidognathous' describe?

• A. Wings of ancient insects.
• B. Parallel downward fangs of mygalomorphs.
• C. Pincer-like fangs of araneomorph spiders.
• D. Mouthparts of crustaceans.

Answer: (B)

Labidognathous describes how the spider’s mouthparts, the chelicerae, are oriented and function. In this arrangement, the fangs are parallel to each other and point downward, with the chelicerae moving in a vertical plane to strike. This pattern is typical of mygalomorph spiders (like tarantulas and trapdoor spiders). It contrasts with araneomorph spiders, whose fangs cross and close like pincers as they move more laterally. The other options refer to wings or crustacean mouthparts, which are not related to this spider cheliceral arrangement.

Labidognathous describes how the spider’s mouthparts, the chelicerae, are oriented and function. In this arrangement, the fangs are parallel to each other and point downward, with the chelicerae moving in a vertical plane to strike. This pattern is typical of mygalomorph spiders (like tarantulas and trapdoor spiders). It contrasts with araneomorph spiders, whose fangs cross and close like pincers as they move more laterally. The other options refer to wings or crustacean mouthparts, which are not related to this spider cheliceral arrangement.