Ceres featherlegs  (Metacnemis angusta)

The Ceres featherlegs is classified as Vulnerable (VU) on the IUCN Red List (1).

Thought to be extinct for many years, the incredibly rare Ceres featherlegs (Metacnemis angustai) is a tiny damselfly that occurs in South Africa. Although the Ceres featherlegs was first described in 1920, it was not seen again until 2003 (1).

The male Ceres featherlegs is bold blue and black, with a greyish-blue and black face. The female has more extensive blue areas, but the blue is typically much paler (2). Like all damselflies, the Ceres featherlegs has four wings that are all of much the same shape and size. The clear wings are held along the length of the slender abdomen when at rest. This separates damselflies from the more robust-looking dragonflies, which hold the wings away from the body during rest (2).

Although originally recorded from the Ceres region in South Africa, the Ceres featherlegs is today known from just one pool near Villiersdorp in the Western Cape (3). Despite intensive searches, this species has not yet been found anywhere else (4).

The single pool occupied by the Ceres featherlegs is situated near a river. The pool is surrounded by bush and contains the water weed Aponogeton (5).  

Virtually no information is available on the behaviour, diet or reproduction of the Ceres featherlegs. However, many aspects of its life history can be assumed to be similar to other damselfly species.

Damselflies are carnivorous, aerial predators, which feed on smaller insects. Sometimes their diet may include other damselflies and dragonflies (2). Damselflies are prey themselves for many species, particularly birds, such as swallows and bee-eaters (2). 

When mating, the male damselfly grasps the female on the neck with grasping appendages situated on the end of the long abdomen. Mating can last from a few seconds to several hours, depending on the species of damselfly. All damselflies lay their eggs on plants that are submerged in water (2). The emerging larva then undergoes several moults, before climbing out of the water at night, ready to make the final, dramatic transformation into the adult form. In the early morning, the larva swallows air, which expands the body so that the larva’s ‘skin’ splits, revealing the adult body. Blood then enters the delicate wings, which expand and harden before the damselfly takes to its maiden flight (2).

The adult Ceres featherlegs can be seen in the South African summer, between November and February (2).

As the Ceres featherlegs is currently known from only one population and is confined to one small pool, it is at great risk of extinction (1).

The Ceres featherlegs is thought to have once had a larger range, but the stream habitat where it was recorded in 1920 has been dramatically changed and degraded, and some streams no longer flow due to over-extraction of water for agriculture and damming (1). Alien invasive trees are also thought to have contributed to this species’ decline, as they shade the streams and pools, altering the habitat (1) (4).

The removal of non-native trees around freshwater habitats has been vital for the survival of the Ceres featherlegs. The single pool where it is currently found is one of the sites at which invasive trees were removed (1).

However, as there is always the risk that these trees could re-grow, ongoing conservation efforts are critical to ensure the future of this beautiful damselfly (1).

Learn about conservation in the Western Cape:

• CapeNature:
  http://www.capenature.co.za/