Systematics and biology of the genus Poltys (Araneae: Araneidae) in Australasia

Contents

Abstract

The genus Poltys C.L. Koch is revised for Australia and partly examined for the wider Australasian region. Five of the ten species originally described from Australia are found to be synonymous with South East Asian species, a further three are synonymous with an Australian species and four which were previously overlooked are newly described, resulting in a total of eight current species recorded from Australia. Poltys coronatus Keyserling, P. keyserlingi Keyserling, P. multituberculatus Rainbow and P. penicillatus Rainbow are synonymised with P. illepidus C.L. Koch; P. microtuberculatus Rainbow is synonymised with P. stygius Thorell; P. bimaculatus Keyserling, P. mammeatus Keyserling and P. salebrosus Rainbow are synonymised with P. laciniosus Keyserling; P. sigillatus Chrysanthus from New Guinea is synonymised with P. frenchi Hogg. Five new species are described, four from Australia, P. grayi sp.nov., P. jujorum sp.nov., P. milledgei sp.nov. and P. noblei sp.nov., and P. timmeh sp.nov. from New Caledonia. A checklist of all Poltys types described from the region, including illustrations, is included. The delimitation of the Australian species is aided and confirmed by DNA sequencing. Sequences from two genes and morphological characters are used to reconstruct a phylogeny of the Australian species. The generic relationships of Poltys are examined in the context of the putative tribe Poltyini (Simon, 1895). No firm conclusions about the relationships of Poltys can be made, however the results indicate that the Poltyini is polyphyletic. The results of field studies are presented; these indicate that P. noblei is less likely to move between web sites than diurnal taxa referenced from other studies. Specimens were shown to sometimes occupy the same, or a closely adjacent web site, for over eight months. Spiders most often move during spring and summer but often remain in the same site throughout winter. Specimens of Poltys noblei are also shown to be unevenly distributed on trees and bushes in respect to aspect and position. It is suggested that these observations indicate the importance of camouflage to deter wasp and bird predators. Specimens of several Poltys species were reared from egg sacs, confirming male-female identification and showing the variation in abdominal shape between siblings. Growth data indicate that sibling males and females cannot normally interbreed; males mature after 2-4 moults, females after 8-11 moults. Field and cage observations of general aspects of Poltys biology are presented including preferred habitat, prey capture and handling, courtship and mating, competition and web construction.