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 angusta – CERES 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.
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.
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
