Commonly confused pairs of Australian arthropods

In the invertebrate world, there are many groups of cryptic species for which identification is difficult, or even impossible, from photographs due to their similar morphology and colouration. In some cases, a single identification gets applied indiscriminately to multiple different (and sometimes even unrelated) species; for example, the name Amenia imperialis is very commonly used for not only true A. imperialis, but all the other Amenia species, and a number of lookalikes (e.g., Rutilia) in an entirely different family. Not only are many online records (on iNaturalist and elsewhere) putatively of A. imperialis not that species, in most cases the photographs do not allow an identification to species anyway.

However, there are many instances for which it is possible to readily differentiate between several similar options. On iNaturalist, there are a number of invertebrates for which two common, morphologically similar species are often confused for each other, but are relatively easy to identify once you know what to look for. In many of these cases, the computer vision will offer both species as suggestions, creating further uncertainty. In this guide, I present ten pairs of commonly observed, and commonly confused, Australian arthropods, and highlight how to differentiate them. A number of these pairs have distributional differences between the two species that can help with identifications in some cases, but I will focus only on morphology here. Note that for all ten pairs there are far more differences between the two species than I have noted, but I have highlighted the most prominent differences/those that are easiest to see.

1 . Trichonephila edulis and Trichonephila plumipes (females)

Above, left: @jacksonnugent
Above, right: @kymelen