Onkaparinga River NP (1st May, 2022)

With a few hours left on day three of the City Nature Challenge I stopped in at Onkaparinga River National Park to search along the start of the Echidna Hike. The section of the hike that runs parallel to Piggott Range Road seems relatively undisturbed, with quite a high number of species in a small area.

First record was an abnormal growth on a Sticky Hop-Bush (Dodonaea viscosa). These growths are quite common with many plants showing at least one patch, and some with dozens. The growth is potentially caused by a Phytoplasma (Genus Phytoplasma). These small genome Bacteria are obligate intracellular parasites of plant phloem tissue, transmitted by sap-sucking Insects. I’ve never noticed any particular Hemiptera associated with these Dodonaeas, but it might be worth taking a closer look. The literature suggests that multiple Hemiptera species are involved, but it seems likely there is a primary transmitter in each area or region. If that’s the case I should be able to find a particular species of Bug on multiple Hop-Bushes.

This time of year identifying some species requires knowledge of either what dried seed pods look like, or be able to recognise the first shoots emerging now the rainy season is beginning. The finished flower stalk and empty fruit capsules of Milkmaids (Burchardia umbellata) are easy to ID, due to the way the stalk branches. The tall flower stalk of the Nodding Chocolate Lily (Arthropodium fimbriatum) is also quite distinct. It can be separated from the stalk of the Common Chocolate-lily (Arthropodium strictum) in that the flowers occur in groups of 2 to 4 emerging from the same axil.

The emerging Fringe-Lilies are easy to recognise from their twining branches, with the Twining Fringe-Lily (Thysanotus patersonii) most common at this location. Also emerging are the leaves of the Blue Stars (Chamaescilla corymbosa), which I used to mistake for Orchids, and can be separated in that they have multiple emerging leaves, whereas the local similar looking Orchids have a single leaf at this stage.

I didn’t really walk slow enough to find many Insect species but did record my second Australian Painted Lady (Vanessa kershawi) for the CNC, and a Mud-nesting Spider Wasps (Genus Fabriogenia) on the hunt.

Onkaparinga River National Park

15.4km2 of steep river valley, remnant Eucalyptus woodland, degraded ex-farmland infested with introduced European Olive, and revegetation sites. Numerous recreational walking tracks and lookouts over the valley and down to the river. Includes Hardy’s Scrub on the the south side of Chapel Hill Road.

iNaturalist Projects

Onkaparinga River National Park, South Australia

Ferals in South Australian Reserves – Onkaparinga River NP

See the full list of 58 observations covering 37 species on iNaturalist