Argiope protensa | |
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Scientific classification ![]() | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Arthropoda |
Subphylum: | Chelicerata |
Class: | Arachnida |
Order: | Araneae |
Infraorder: | Araneomorphae |
Family: | Araneidae |
Genus: | Argiope |
Species: | A. protensa
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Binomial name | |
Argiope protensa |
Argiope protensa, commonly known as the tailed grass spider[2] or teardrop spider,[3] is a species of spider in the orb weaver family, Araneidae. This species is fairly common and widespread in Australasia,[4] but like many spider species, little is known of its ecology, biology, or life history.[5]
Argiope protensa is a slender, medium-sized spider, reaching a body length of 13 – 25 mm.[3][6][7] 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.[7] 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.[6] In Australia, Argiope protensa can be distinguished from A. probata (the only other Argiope species with a similarly-shaped abdomen) by examining morphological characteristics of the epigyne.[7]
The tailed grass spider's web is variable, usually quite small (especially compared to those of other Argiope species), and may be constructed close to the ground[8] and oriented on a plane anywhere between vertical and horizontal.[3] A 2022 analysis of 262 photographs showing 124 different tailed grass spider webs across Australia and New Zealand showed 38.7% contained a structure known as a stabilimentum,[8] the purpose of which is yet to be determined.[9]
Argiope protensa is recorded from Australia, New Zealand, New Caledonia and New Guinea.[4] It is considered native to New Zealand, believed to have arrived from Australia by natural means;[10] scrutiny of early collection records and/or comparative genetic analysis would be required to confirm this and estimate a time of first arrival.[11] 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.[12]
The length of the tailed grass spider’s life cycle is unknown but, like similar species, probably lasts no more than two years.[13] Females reach maturity in midsummer, and produce cup-shaped egg masses in the late summer.[3] It is unknown when the young hatch from their eggs. Ballooning is probably an important mechanism by which the young disperse to new habitats,[14] and is likely how this species reached New Zealand from Australia. [15]
As an orb-weaving spider, Argiope protensa is a generalist predator and will consume any invertebrates it can capture and subdue, though some preferential selection of prey may occur, as seen in other araneid spiders.[16][17][18] Prey is usually restrained by wrapping with broad swathes of dense silk, which is a common behaviour in other species in this genus.[9]
Argiope protensa was first described from Australia by L. Koch in 1872;[19] in 1885 it was also described as Epeira attenuata by Urquhart from specimens collected in New Zealand.[6] Several other synonyms exist from different collection locations.[4] Taxonomic confusion continued until 1971, when Chrysanthus[20] confirmed that specimens collected from New Guinea matched Koch’s original description; in 1983 Levi agreed that similarities in genital morphology suggested many of the previously-described Australasian species were synonyms.[7] In 2017, phylogenetic analysis by Wheeler et al. confirmed the placement of Argiope within the family Araneidae.[21]