Ceres Streamjack (Spesbona angusta)

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

Find the Ceres Streamjack in the FBIS database (Freshwater Biodiversity Information System) here.

Family Platycnemididae

Spesbona angustaCERES STREAMJACK

This species was moved from the genus Metacnemis in 2013.

Identification

Very Small Size

Length up to 30mm; Wingspan reaches 38mm.

Sexes are dichromatic. Colouration varies according to temperature. Ranges from blackish when cold to grey then blue and finally mauve/purple when in full sun.

Click here for more details on identification.

Spesbona angusta – Male
Theewaterskloof, Western Cape
Photo by Desire Darling

Habitat

Inhabits small pools connected to streams and meandering rivers. Favours sites with an abundance of overhanging grass and other floating and emergent vegetation.

Habitat – Theewaterskloof, Western Cape
Photo by Sharon Stanton

Behaviour

Typically sits lengthwise along a grass or reed stem, usually low down close to the water. Males and females often found together.

On the wing from late August until the end of December. Mainly an early season species. See Phenology below.

Status and Conservation

Rare and localised endemic. Listed as Endangered in the IUCN Red List of Threatened Species.

Distribution

Spesbona angusta is endemic to the Western Cape, South Africa. Likely to be more widespread than current records show. Originally known only from near Ceres down to Franschoek, but now known to occur near Riversdale and in the Sedgefield/Knysna area.

Below is a map showing the distribution of records for Ceres Streamjack 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.

Phenology

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.