COLLEMBOLA > SYMPHYPLEONA > Dicyrtomidae > Dicyrtominae

Dicyrtoma fusca is a small, typically less than 2mm long, globular springtail species, that is the only British representative of its genus.

Whilst generally described as having a matt brownish-purple colour, it actually has considerable variation that ranges from almost pale yellow to dark maroon with equally varying marbled patterning. The head and body though are always the same concolourous shade. I believe that individuals whose appearance is regarded as normal, or more typical of the species, are treated as Dicyrtoma fusca var.1, as there's a much rarer, near black, melanistic form known as Dicyrtoma fusca var.2, and a leucistic form that have dark ocelli on a pale eyepatch known as Dicyrtoma fusca var.rufescens.     

Members of the Dicyrtomidae family are characterised by having a very short fourth antennal segment, and in Dicyrtoma fusca the third antennal segment is not clearly subdivided, whereas in Ptenothrix atra it is. However, with species this small, features like this are unlikely to be clearly visible in standard macro photos, and certainly not when looking for more specific characters such as details regarding the claw on the foot or whether the outer edges of the mucro (the end segment of the tiny furcula) are serrated! In the right light and from the right angle, photos should show short spines on the abdomen though, and setae on the dorsal surface of the rear end, which are longer and more erect in Ptenothrix atra.

Notwithstanding those comments, I'd far prefer to get photos of this particular species checked out if I can because, although the general appearance of some individuals may be reasonably clear, they could easily be misidentified, as was the case with the one that turned out to be Ptenothrix atra - next page - that I previously thought could be ignored due to its rarity!