Marbled malachite (Ecchlorolestes peringueyi)
Classified as Vulnerable (VU) on the IUCN Red List (1).
This large damselfly earns its common name for its dark metallic, cryptic colouration (2), which perfectly camouflages it against the mottled, lichen-covered boulders upon which it habitually sits (3). The body is primarily black, but features brown markings along the long, slender abdomen, particularly at the joints between segments, and there is bluish, slate-grey colouring at the tip.
This South African endemic is known only from protected areas within the Cape Fold Mountains of the Western Cape (4).
The marbled malachite is found along clear, shallow streams with an abundance of large, lichen-covered boulders. Two populations exist at high elevation locations over 1,000 metres above sea level, while a third population is at 400 metres above sea level (1).
Virtually nothing is known of the marbled malachite’s reproductive biology, life history patterns or feeding behaviour. Nevertheless, there are general biological characteristics of dragonflies and damselflies (Odonata) that are likely to apply. Odonata species start their life as aquatic larvae or nymphs, passing through a series of developmental stages or ‘stadia’ and undergoing several moults as they grow. This larval period can last anything between three months and ten years, depending upon the species. Before the final moult (emergence), metamorphosis occurs in which the larvae transform into the adult form. After emergence, adults undergo a pre-reproductive phase known as the maturation period, and this is when individuals normally develop their full adult colour. Odonata usually feed on flying insects and are generalised, opportunistic feeders, often congregating around abundant prey sources such as swarms of termites or near beehives (5).
There is often fierce competition between males for access to reproductive females, and females typically begin to lay eggs in water immediately after copulation, often guarded by their mate. However, females of some species can store live sperm in their body for a number of days (5).
Being a habitat specialist, this damselfly was probably never particularly widespread or abundant, but early records nevertheless reveal that it was once found at many more localities than it is today. Despite historical declines, however, the current population appears to be stable, both in range and size, and habitat destruction, mostly for plantation forestry, has largely subsided. Even so, the species remains vulnerable to several threats that have the potential to impact dramatically on such small and specialised populations (1). In particular, alien invasive trees, which shade out the habitat, are considered one of the most pervasive and significant threats facing specialised, endemic South African dragonflies and damselflies (Odonata) (3). Introduced trout are also present in a number of South African rivers, and pose a serious threat to endemic dragonflies and damselflies through predation (1).
Fortunately, the marbled malachite occurs within protected areas. Additionally, a massive national rehabilitation programme (Working with Water Programme) began in 1995 with the aim of eradicating invasive alien plants in South Africa. The programme has been a fantastic success story, with other dragonflies and damselflies (e.g. harlequin sprite Pseudagrion newtoni) that were presumed to be extinct being rediscovered along river stretches where invasive alien trees were removed and the natural vegetation re-established (6). The programme has also greatly benefited the marbled malachite (3), but it is imperative that there is no further encroachment of plantation forestry (1). It is also important that populations are regularly monitored to ensure that they are remaining stable (1). However, for the time being at least, this enigmatic damselfly is thought relatively safe from the threat of extinction.
Authenticated (12/07/2006) by Professor Michael Samways, Department of Conservation Ecology and Entomology and Centre for Agricultural Biodiversity, Stellenbosch University.
- Cryptic colouration: colouring that camouflages or disguises a species.
- Endemic: a species or taxonomic group that is only found in one particular country or geographic area.
- Metamorphosis: an abrupt physical change from the larval to the adult form.
IUCN Red List (December, 2009)