Record-setting tarantulas have the longest sex organs to avoid being eaten by females

New tarantulas have record-long organs to avoid female attacks, reaching 2 inches.

: Four new tarantula species, including Satyrex ferox, were discovered with exceptionally long palps which led to their classification into a new genus. The arachnologist Alireza Zamani suggests these extended palps allow males to keep a safer distance from their aggressive female partners during mating. Satyrex ferox, noted for its fierce nature, measures a legspan of 5.5 inches and palps up to 2 inches. Researchers attributed the formation of this new genus, Satyrex, to significant morphological and molecular differences from related species.

Tarantulas have intrigued scientists with their complex behaviors and fascinating adaptations. Researchers have recently identified four new tarantula species that exhibit unique sexual adaptations leading to their classification into a new genus named Satyrex. These tarantulas are primarily found in the Arabian Peninsula and the Horn of Africa and are distinct from their closest relatives both on morphological and molecular grounds.

These species, named Satyrex ferox, S. arabicus, S. somalicus, and S. speciosus, have male tarantulas with the longest known palps—limbs used in sperm transfer during mating among other functions. In male members of the Satyrex ferox species, these palps stretch nearly 2 inches long, a characteristic believed to help males avoid fatal post-mating aggression from females. Zamani explains this evolution is akin to striking a balance between mating success and survival.

Satyrex ferox is particularly noted for its aggressive nature. Zamani, a lead researcher, highlighted in a study published by ZooKeys that this species responds to disturbances by raising its front legs and producing a loud hissing sound through a friction-based mechanism. The name 'ferox' aptly translates to 'fierce,' a testament to their highly defensive behavior.

While Satyrex ferox is notably fierce, the other species in this new genus have been named based on their defining characteristics or origins. For instance, S. speciosus derives its name from their visually striking appearance, whereas S. arabicus and S. somalicus have been named after their regional habitats. This discovery also led to the reclassification of a former species in the genus Monocentropus, now renamed as S. longimanus.

Understanding the evolutionary significance of these traits offers valuable insights into the behaviors and survival strategies of tarantulas. The creation of a new genus for these species underlines the critical role of morphological traits in species classification and paves the way for future studies on spider taxonomy, targeting how size and behavior intertwine in these fascinating arachnids.

Sources: ZooKeys, Gizmodo, Pensoft

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