Sminthurinus species are very variable in colour pattern and it is essential to examine the presence or absence of ventral subapical setae on the dens in order to make a correct identification. The'concolor-group' has TWO ventral subapical setae on the dens. (Figs. 1, 2). An easier equivalent test is to see whether abdomen 5 and 6 are fused (aureus group) or distijunct (trinotatus group).
Sminthurus concolor is black-violet in colour and is found out of doors. Sminthurinus trinotatusis also found out of doors and is predominantly black with a prominent white spot on either side of the abdomen. Two other species have been recorded from glasshouses, or flower pots inside buildings. These are Sminthurinus domesticus (bluish-black all over, sometimes with a yellow median band) and Sminthurinus igniceps(body bluish-black, head white or pale yellow). However, the ease with which springtails can be imported on exotic plants means that the exact origin and identity of these specimens remains uncertain.
Sminthurus domesticusis a rare species recorded from the Cactus House at Kew Gardens (Lawrence, 1967) and soil in flower pots in the Natural History Museum in May 1956 . It reaches 1.0 mm in length and is bluish-black all over, sometimes with a yellow median band. The fourth antennal segment (ant4) is NOT subdivided. Both edges of the mucro are serrated (Fig. 2). In females, the long setae surrounding the anus are expanded at the base and the sub-anal appendages (SAA) are feathery at the tips. The empodium of the second and third legs (leg2 and leg3) is slightly shorter than the claw, but is longer than the claw on leg1. The tenaculum (i.e. the 'catch' for the furca) has two setae. Apparently, Sminthurinus trinotatus is the only member of the 'concolor-group' with only one seta on the tenaculum.
Paul Ardon recently refound Sminthurinus domesticus on imported orchids from a distributor in Newton Abbot, Devon.