Eastern Duskhawker (Gynacantha usambarica)

View the above photo record (by Ryan Tippett) in OdonataMAP here.

Find the Eastern Duskhawker in the FBIS database (Freshwater Biodiversity Information System) here.

Family Aeshnidae

Gynacantha usambarica – EASTERN DUSKHAWKER

Identification

Very Large

Length up to 78mm; Wingspan attains 103mm.

The sexes are similar but females have somewhat duller colouration and a reduced amount of blue on the saddle.

The key distinguishing features of the Eastern Dusk-hawker include the small blue saddle, plain green thorax, three-celled anal triangle and 21-27 Ax veins in the forewing.

Most easily confused with the Little duskhawker (Gynacantha manderica) but that species is smaller and predominantly brownish rather than green. May also be mistaken for the Brown Duskhawker (Gynacantha villosa), but that species is larger, lacks bright colouration and has a four-celled anal triangle.

Click here for more details on identification of the Eastern Duskhawker.

Habitat

A forest dwelling species of coastal areas. Inhabits various forest types such as coastal, dune and especially swamp forest. It is also found in mangroves. Hunts in clearings at dusk. Breeds at forested lakes, streams and rivers.

Behaviour

A crepuscular species that rests during the day in the deep shade of low undergrowth. Hangs from a perch when at rest. If flushed, it does not fly far before settling again. Emerges at dusk to hunt in clearings and along roads and pathways. Frequently joins other dragonflies in mixed species hunting swarms at dusk. Gynacantha usambarica hunts on the wing and has a smooth, fast flight. May forage around tree tops and low to the ground, as it patrols back and forth along a selected route.

Status and Conservation

Fairly common but localised along the coastal plain of KwaZulu-Natal. It is listed globally as of Least Concern in the IUCN Red List of Threatened Species. It is however, listed as Vulnerable in South Africa due to pressure placed on its habitat by urbanisation and agriculture. Gynacantha usambarica is confined to indigenous forests and is intolerant of habitat degradation.

Distribution

This species is confined to Eastern and Southern Africa. Occupies a narrow strip along the coastal plain from Kenya down to South Africa. It has also been recorded in Malawi, but in general, is seldom found far from the coast.

Below is a map showing the distribution of records for Eastern Duskhawker 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.