Halfshade Dropwing (Trithemis aconita)

View the above photo record (by Desire Darling) in OdonataMAP here.

Find the Halfshade Dropwing in the FBIS database (Freshwater Biodiversity Information System) here.

Family Libellulidae

Trithemis aconita HALFSHADE DROPWING

Lieftinck, 1969

Identification

Small size

Length up to 41mm; Wingspan attains 67mm.

The Halfshade Dropwing is one of a handful of small, dark blue species in the region. Trithemis aconita can be told apart from these species, except Trithemis hecate, by its slender abdomen and habitat choice.

Males most resemble Trithemis hecate (Silhouette Dropwing). Trithemis aconita can be differentiated by its thin black abdomen with yellow streaks. This abdomen pattern seldom becomes obscured with pruinosity.

Young male Silhouette Dropwings (Trithemis hecate), also have thin abdomens with yellow streaks. This pattern becomes obscured with dark blue pruinosity once mature. The two species also differ markedly in behaviour and habitat choice.

Females are easily confused with other Trithemis species. They are best identified by their association with the males.

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

Trithemis aconita – Male
Mkuze River, KwaZulu-Natal
Photo by Ryan Tippett

Habitat

Frequents shaded rivers and streams in woodland and forest habitats. It requires overhanging trees and usually running water with rocks.

Habitat – Nwanedi, Limpopo
Photo by John Wilkinson

Behaviour

The Halfshade Dropwing is a shade dwelling species. It also sits in dappled light and sunspots near the water but is seldom far from shade. It is shy and weary, and flies into the tree tops at the first sign of disturbance. Perches on twigs under the overhanging canopy of trees. Sometimes also sits low down, close to the water on rocks and exposed tree roots.

Status and Conservation

Uncommon and very localised in South Africa. It is listed as of Least Concern in the IUCN Red List of Threatened Species. This species is intolerant of damage to its riverine home and is only found in in good quality habitat.

Distribution

Erratically distributed throughout most of sub-Saharan Africa. It is largely absent from the dry arid parts of Namibia, Botswana and South Africa. Its South African range is confined to the perennial savanna rivers of the Limpopo and Mpumalanga provinces and the forested rivers of coastal Kwa-Zulu-Natal.

Below is a map showing the distribution of records for Halfshade 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: Skaduvalvlerkie (Afrikaans)

Type Locality: Kisamamba, DRC

Recommended citation format: Loftie Eaton. M; Hofmeyr S; Tippett RM; Underhill L. Halfshade Dropwing Trithenis aconita. Biodiversity and Development Institute. Available online at https://thebdi.org/2020/05/12/halfshade-dropwing-trithemis-aconita/

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.