Highland Dropwing (Trithemis dorsalis)

The photo above (by Alan Manson) can be viewed in OdonataMAP here.

Find this species in the FBIS database (Freshwater Biodiversity Information System) here.

Family Libellulidae

Trithemis dorsalis HIGHLAND DROPWING

(Rambur, 1842)

Identification

Small to medium size

Length up to 40mm; Wingspan attains 65mm.

Only likely to be confused with the very similar Trithemis furva (Navy Dropwing). Males of the two are best identified in the hand by examining the shape of the secondary genitalia. The males can also (mostly) be told apart by checking the last Ax vein in the front wings. In Trithemis furva the last Ax vein extends as far as the subcostal vein and does not reach the radial vein. Trithemis dorsalis shows Ax veins that cross the subcostal vein to meet up with the radial vein.

In addition, the two species can be tentatively identified based on their preferred habitat choice. Although they co-occur at many sites, the Highland Dropwing is far more numerous than the navy dropwing at higher altitudes.

Click here for more details on identification of the Highland Dropwing.

Trithemis dorsalis – Male
Elands River, KwaZulu-Natal
Photo by Ryan Tippett
Trithemis dorsalis – Female
Lake Naverone, KwaZulu-Natal
Photo by Ryan Tippett

Habitat

Inhabits the fringes of rivers, streams and dams. Prefers slow moving sections of rivers and is far less regular along fast flowing stretches. Common along the vegetated fringes of dams that are lined with reeds and sedge.

Habitat – Wakkerstroom, Mpumalanga
Photo by Rowan Poortier

Behaviour

A conspicuous species that perches in the open on emergent or fringing vegetation. At rest sits with its wings drooped downwards in typical ‘dropwing’ fashion. Most regular above 700m. a.s.l. but regular at lower altitudes in the Western Cape.

On the wing from October to May.

Status and Conservation

Common in higher altitude areas. Listed as of Least Concern in the IUCN Red List of Threatened Species.

Distribution

Locally distributed across the highland regions of Eastern and Southern Africa. Also occurs in Central Angola.

In South Africa Trithemis dorsalis is predominantly a species of the Drakensberg and Highveld, but is widespread in mid to high altitude regions, from the SW Cape to N Limpopo.

It is found in Angola, the Democratic Republic of the Congo, Guinea, Kenya, Mozambique, Sierra Leone, South Africa, Tanzania, Uganda, Zambia, Zimbabwe, possibly Burundi, and possibly Malawi.

Below is a map showing the distribution of records for Highland Dropwing in the OdonataMAP database as at February 2020.

The next map below is an imputed map, produced by an interpolation algorithm, which attempts to generate a full distribution map from the partial information in the map above. This map will be improved by the submission of records to the OdonataMAP section of the Virtual Museum.

Ultimately, we will produce a series of maps for all the odonata species in the region. The current algorithm is a new algorithm. The objective is mainly to produce “smoothed” maps that could go into a field guide for odonata. This basic version of the algorithm (as mapped above) does not make use of “explanatory variables” (e.g. altitude, terrain roughness, presence of freshwater — we will be producing maps that take these variables into account soon). Currently, it only makes use of the OdonataMAP records for the species being mapped, as well as all the other records of all other species. The basic maps are “optimistic” and will generally show ranges to be larger than what they probably are.

These maps use the data in the OdonataMAP section of the Virtual Museum, and also the database assembled by the previous JRS funded project, which was led by Professor Michael Samways and Dr KD Dijkstra.

Further Resources

Virtual Museum (OdonataMAP > Search VM > By Scientific or Common Name)

More common names: Hooglandvalvlerkie (Afrikaans)

Type Locality: Cape Province, South Africa

Recommended citation format: Loftie Eaton. M; Hofmeyr S; Tippett RM; Underhill L. Highland Dropwing Trithenis dorsalis. Biodiversity and Development Institute. Available online at http://thebdi.org/2020/05/08/highland-dropwing-trithemis-dorsalis/

Dragonfly Atlas: Megan Loftie-Eaton, Sally Hofmeyr, Ryan Tippett & Les Underhill
Dragonfly Atlas: Megan Loftie-Eaton, Sally Hofmeyr, Ryan Tippett & Les Underhill
Megan Loftie-Eaton is our communications, social media and citizen science coordinator. Prior to her work for the BDI, she coordinated OdonataMAP, the Atlas of African Odonata. Sally Hofmeyr has many years' experience in the academic world, writing her own material and editing the work of others. Her academic background is in the natural sciences: her PhD and first postdoc in ornithology and environmental change (Animal Demography Unit, University of Cape Town). Ryan Tippett is an enthusiastic contributor to Citizen Science and has added many important and interesting records of fauna and flora. He has been a member of the VMU since 2014 and has currently submitted over 11000 records. He is also on the expert identification panel for the Odonata Map project. Prof Les Underhill has been Director of the Animal Demography Unit (ADU) at the University of Cape Town since it started in 1991. Although citizen science in biology is Les’s passion, his academic background is in mathematical statistics.