Brown recluse spiders have what distinguishing features?

The distinguishing features of brown recluse spiders primarily include their unique eye arrangement and the characteristic violin-shaped marking on their abdomens. These spiders have six eyes arranged in pairs, rather than the more common eight eyes found in most spider species. This semi-circular arrangement of the eyes is a key identifier for the brown recluse, setting them apart from other spiders. Additionally, the brown violin marking, which is typically darker than the rest of the body and located on the top of the abdomen, aids in its identification.

The other options present characteristics that do not apply to the brown recluse. For instance, they are not known for bright colored abdomens but rather exhibit a more uniform brown coloration. Regarding body size, while they are medium-sized spiders, they are not significantly larger than many other spiders. Lastly, while their legs are long, the absence of markings on them is not a distinctive feature; many spiders also have long legs without markings. Thus, the combination of the unique eye arrangement and the violin marking corroborate the identification of the brown recluse spider effectively.