(245BAbor) Ballistura borealis (Axelson, 1905)

Ballistura borealis is a rare species of up to 1.3 mm in length that is known only from the shores of Scottish Lochs. Nelson (1981) recorded it in considerable numbers from Loch Laidon and there are additional specimens in the NHML slide collection from Loch Leven, also collected by Nelson. Ballistura borealis is dark violet in colour, has a small oval PAO, and 8+8 ocelli. The mucro has two teeth, only the apical part of the ventral side of the dens has setae (Fig. 1) and there are no ventral manubrial setae. The tibiotarsus of the foot bears a single clavate tenant seta (Fig. 2). This species should be looked for on the margins of lakes in northern England and Scotland where it is sure to turn up in many more places.

 

 

 

Fig. 1: Furca of Ballistura borealis collected from Loch Laidon in Scotland in June 1980 by J.M. Nelson . man, manubrium.

Fig.2: Foot of leg 3 of Ballistura borealis collected from Loch Laidon in Scotland in June 1980 by J.M. Nelson. Note the single clavate tenant seta on the distal tibiotarsus (*).

 
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