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.
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.
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/
