Abstract
Web structure and web-building behavior of Patu sp. were observed in field. This species made a horizontal orb web with very fine mesh. The web had many sticky spirals and a great number of radii in comparison with typical orb-weavers. The process of web-building behavior after spinning the sticky spirals was characteristic. On a return trip from the hub to the frame, the spider made two supplementary radii. After the supplementary radii were completed, the spider returned to the hub and loosened some radii. These characteristic behavior suggests that Patu sp. was derived from the orb-weaving ancestor and was related to the spiders of Anapidae and Mysmenidae.
