Megalothorax minimus is a very common and widespread blind species with a highly characteristic appearance (Figs. 1,2, and 3). Although it is tiny (maximum length 0.5 mm), careful examination of the underside of rotting wood and leaf litter with a hand lens will often reveal specimens walking along with a gait that reminds me of a tiny old man hunched in a baggy coat.
     The empodium of the foot is about half as long as the claw (Fig. 4) and the third (ant3) and fourth (ant4) antennal segments are not clearly separate (Fig. 5). The edges of the mucro are smooth (Fig. 6), and the sensory field on the abdomen (Fig. 7) is bordered by five marginal setae (Fig. 8).

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Fig. 1 (above): Megalothorax minimus (arrow) of 0.25 mm in  length under the head of Tomocerus longicornis in a garden in Reading.

Fig. 2 (above): Megalothorax minimus of 0.35 mm in  length in a garden in Reading. The specimen appears to have been grazing on green algae. The four 'compartments' of the gut are clearly visible through the cuticle (cf. Fig. 3)

Fig. 3 (above): Megalothorax minimus collected from Lamorna Cove, Cornwall in April 1955 by T. Clay. Note the four 'compartments' of the gut (arrows).

Fig. 4 (above): Feet of the first and third legs of Megalothorax minimus collected from Parliament Hill Fields, London in December 1952 by D.S. Murphy.

Fig. 5 (above): Terminal part of the antenna of Megalothorax minimus collected from Tringford Reservoir in February 1964 by Peter Lawrence.

Fig. 6 (above): Furca of the same specimen of Megalothorax minimus shown in Fig. 5.

Fig. 7 (above): Abdominal sensory organ (seen in profile) of the same specimen of Megalothorax minimus shown in Fig. 4).

Fig. 8 (above): Abdominal sensory organ  of the same specimen of Megalothorax minimus shown in Fig. 5. The sensory organ is surrounded by five setae (1 to 5).