Tailed Forest Spider

Argiope protensa is a slender, medium-sized spider, reaching a body length of 13 – 25 mm. Its abdomen is distinctively elongate, tapering to a long “tail” extending beyond the ventrally-positioned spinnerets — though immature and/or male specimens may not clearly show this characteristic. The dorsal abdomen has on each side a finely pubescent strip of short, silvery hairs, which become sparse closer to the apex. Four to six pairs of weakly indented spots border the variably-coloured, hairless medial line; similar hairless dark strips run along the sides of the abdomen. Ventrally, the abdomen is dark and sparsely-haired; two pale stripes run longitudinally down its entire length to the apex. The cephalothorax makes up about a quarter of the body length, and is covered in silvery-grey hairs on its dorsal surface. Colouration of the legs can vary between individuals; some are almost uniformly grey-brown, while others have strongly contrasting bands of dark and light colour along their lengths. In descending order, the relative leg lengths are 1, 2, 4, 3. In Australia, Argiope protensa can be distinguished from A. …

Argiope protensa is recorded from Australia, New Zealand, New Caledonia and New Guinea. It is considered native to New Zealand, believed to have arrived from Australia by natural means; scrutiny of early collection records and/or comparative genetic analysis would be required to confirm this and estimate a time of first arrival. A 2014 study analysed changes in spider assemblage composition of Australian grasslands across a 900 km environmental gradient, and found a strong positive relationship between A. protensa and taller vegetation with high intra-tussock density.

The length of the tailed grass spider’s life cycle is unknown but, like similar species, probably lasts no more than two years. Females reach maturity in midsummer, and produce cup-shaped egg masses in the late summer. It is unknown when the young hatch from their eggs. Ballooning is probably an important mechanism by which the young disperse to new habitats, and is likely how this species reached New Zealand from Australia.