(254CRthe) Cryptopygus thermophilus (Axelson, 1903)

Cryptopygus thermophilus (Fig. 1) is moderately common and appears to be confined to Ireland, Wales and southern England. It is greyish in colour, reaches a maximum length of 1.0 mm, and possesses an oval post-antennal organ with eight ocelli on each side of the head. The fifth (abd5) and sixth (abd6) abdominal segments are fused. The furca is longer than the head (Fig. 1) and the mucro has two teeth (Fig. 2). The dorsal side of abd5/6 has several long setae which bear a fringe of tiny 'hairs' about halfway along their length (Fig. 3). Potapov has christened these 'foil setae' (in relation to fencing swords).

Despite the sparse map, Peter Shaw's experience is that this species is common on bare 'brownfield' ex-industrial sites, with especially high densities on pulverised fuel ash sites in southern England.  Another recent record is from bare ground near the M25 in Kent.  The specific name 'thermophilus' means 'heat loving' - a name that seems to describe its ecology.




Fig. 1: Cryptopygus thermophilus of 1.0 mm in length collected from Woking, Surrey (collector and date not known). The fifth and sixth abdominal segments are fused (5/6). Note that there are only two thoracic segments with clear dorsal tergites (the tergites labelled th1 and th2 in the photo are the tergites of thoracic segments 2 and 3 respectively).

Fig. 2: Mucro of Cryptopygus thermophilus collected from Mitcham Common in August 1977 by Brian Pitkin.

Fig. 3: A foil seta on the posterior abdomen (abd) of the same specimen of Cryptopygus thermophilus shown in Fig. 2.

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