(049/XLtul) Xenylla tullbergi (Börner 1903)
Xenylla tullbergi is a rare species known only from two specimens (Ireland and Cornwall). It is bluish-grey in colour and reaches a length of only 0.7 mm. Xenylla tullbergi has a tiny furca (fused mucro/dens only about 0.6 times the length of a foot claw). A unique character is the presence of only one seta on each dens (Figs. 1 and 2). However, this is difficult to see and the species is probably more common than current records would indicate.
Figure 1: Lateral view of the furca of Xenylla tullbergi collected from Porthallow, Cornwall in June 1975 by Peter Lawrence (identification confirmed by M.M. da Gama). The dens and mucro are fused. man, manubrium.
Figure 2: The same specimen as Fig. 1 at a slightly different plane of focus showing the single seta on the dens of the furca.
Figure 3: Anal spines (arrow) of the same specimen of Xenylla tullbergi shown in Fig. 1.
Figure 4: First (leg1) and second (leg2) pairs of legs of Xenylla tullbergi collected from Boyle, Co. Sligo in October 1950 by Peter Lawrence. Legs1 each have two long clavate setae (*) on the dorsal side of the tibiotarsus.