Scorpion-tailed Spiders (Genus Arachnura)

Arachnura is a genus of orb-weaving spiders within the family Araneidae, subfamily Araneinae, and tribe Poltyini. The genus is distributed primarily in tropical and subtropical regions of South and Southeast Asia, East Asia, Australia, and nearby islands. Species of Arachnura are typically found in forests, forest edges, gardens, and shrublands, where they inhabit vegetation suitable for web construction.

Members of the genus Arachnura are medium-sized orb weavers best known for their highly distinctive elongated abdomen, which often extends into a long, tail-like projection. This unusual body shape gives them a striking appearance and plays a role in camouflage, as the elongated abdomen can resemble plant material such as stems, dried leaves, or debris when the spider is at rest. Coloration is generally cryptic, consisting of browns, grays, and muted greens, sometimes with subtle markings.

Morphologically, Arachnura species possess the typical orb-weaver body plan, with a relatively small cephalothorax and long, slender legs adapted for web construction. The elongated abdominal extension is the most characteristic feature of the genus. As with other araneids, species identification relies primarily on the structure of the male palpal organs and the female epigyne.

Behaviorally, Arachnura spiders are mostly nocturnal. They construct vertical orb webs at night to capture flying insects and usually rest at the center of the web or nearby. During the day, individuals often retreat to surrounding vegetation, where their cryptic shape and coloration help them avoid detection. When disturbed, they may drop from the web on a silk line.

Ecologically, species of Arachnura are predators of flying insects and contribute to the regulation of insect populations in forest and garden ecosystems. Their unusual body form and web-building behavior make Arachnura a distinctive and easily recognizable genus within the orb-weaving spiders.