Physical structures built by animals challenge our understanding of biological processes and inspire the development of smart materials and green architecture. It is thus indispensable to understand the drivers, constraints, and dynamics that lead to the emergence and modification of building behavior. Here, we demonstrate that spider web diversification repeatedly followed strikingly similar evolutionary trajectories, guided by physical constraints. We found that the evolution of suspended webs that intercept flying prey coincided with small changes in silk anchoring behavior with considerable effects on the robustness of web attachment. The use of nanofiber based capture threads (cribellate silk) conflicts with the behavioral enhancement of web attachment, and the repeated loss of this trait was frequently followed by physical improvements of web anchor structure. These findings suggest that the evolution of building behavior may be constrained by major physical traits limiting its role in rapid adaptation to a changing environment.

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Many animals utilize self-built structures – so-called extended phenotypes – to enhance body functions, such as thermoregulation, prey capture or defence. Yet, it is unclear whether the evolution of animal constructions supplements or substitutes body functions. Here, using Austral brown spiders, we explored if the evolutionary loss and gain of silken webs as extended prey capture devices correlates with alterations in traits known to play an important role in predatory strikes - locomotor performance and leg spination. For this purpose, we combined the reconstruction of the phylogeny of the Austral marronoid clade of spiders based on UCE target sequence capture with the assembly of kinematic, morphological and ecological data. We found that in this group extreme locomotor performance, with running speeds of over 100 body lengths per second, evolved repeatedly – both in web builders and cursorial spiders. There was no correlation with running speed, and leg spination only poorly correlated, relative to the use of extended phenotypes, with all of these traits showing highly mosaic, independent evolutionary patterns. This indicates that the use of webs does not reduce the selective pressure on body functions involved in prey capture and defence per se.

Austrocarausius Brock, 2000 is a stick insect (Phasmatodea: Lonchodidae) genus containing two species restricted to the tropical rainforests of northern Queensland. Recent specimen collections between the two species’ type localities, Lizard Island and Rockhampton, have suggested that Austrocarausius might represent more than the two nominal species. Here, we apply morphological and molecular analyses to revise the taxonomy of this genus. Using both field-collected and historic museum samples, we developed morphological species hypotheses and descriptions. Genetic sequencing of mitochondrial COI and 16S were undertaken for species delimitation and phylogenetic analysis, including an estimate of the evolutionary timescale of the genus. Based on these results, we propose nine new Austrocarausius species, increasing the number of species in the genus to eleven: A. nigropunctatus (Kirby, 1896), A. mercurius (Stål, 1877), A. coronatus sp. nov., A. decorus sp. nov., A. eirmosus sp. nov., A. gasterbulla sp. nov., A. tuberosus sp. nov., A. macropunctatus sp. nov., A. truncatus sp. nov. A. waiben sp. nov. and A. walkeri sp. nov. Our results suggest Austrocarausius species diversified over the last c. 25–70 Ma, resulting in the now endemic distributions in the tropical rainforests of the central and northern Queensland coasts. This is the first integrative systematic study of an Australian phasmid genus, combining morphological, molecular and biogeographical methods. Additional species of Austrocarausius likely remain undescribed as can be inferred from methodical sampling of rainforest patches along the Queensland coast.

The Phasmida genus Candovia comprises nine traditionally recognized species, all endemic to Australia. In this study, Candovia diversity is explored through molecular species-delimitation analyses using the COIFol gene fragment and phylogenetic inferences leveraging seven additional mitochondrial and nuclear loci. Molecular results were integrated with morphological observations, leading us to confirm the already described species and to the delineation of several new taxa and of the new genus Paracandovia. New Candovia species from various parts of Queensland and New South Wales are described and illustrated (C. alata sp. nov., C. byfieldensis sp. nov., C. dalgleishae sp. nov., C. eungellensis sp. nov., C. karasi sp. nov., C. koensi sp. nov. andC. wollumbinensis sp. nov.). New combinations are proposed and species removed from synonymy with the erection of the new genus Paracandovia (P. cercata stat. rev., comb. nov., P. longipes stat. rev., comb. nov., P. pallida comb. nov., P. peridromes comb. nov., P. tenera stat. rev., comb. nov.). Phylogenetic analyses suggest that the egg capitulum may have independently evolved multiple times throughout the evolutionary history of these insects. Furthermore, two newly described species represent the first taxa with fully developed wings in this previously considered apterous clade.