COLLEMBOLA > SYMPHYPLEONA > Bourletiellidae

The SYMPHYPLEONA order comprises six families, Arrhopalitidae, Bourletiellidae, Dicyrtomidae, Katiannidae, Sminthuridae and Sminthurididae, which together include around 40 globular-bodied species in 18 or so genera. Many are either rarely recorded or even doubtful. In fact, less than half are regarded as common and, even then, it can be down to location and habitat. The Arrhoplitidae family is a classic example because, although it includes seven recognised species, only two are likely to be seen, and then only in or around the entrance to caves. For that reason alone, I don't expect to be able to add either of those species, but the remaining five families are represented here to some degree.

In respect of Bourletiellidae family, there are now, probably no more than seven species that could be found, and only three that are regarded as common; Bourletiella arvalis, Bourletiella hortensis and Deuterosminthurus pallipes. These species are widespread and, in suitable habitat, can be abundant, but due to their tiny size are rarely recorded.  

Bourletiella hortensis is a blueish-black species that grows to little more than 1mm. some individuals are paler, but the lower half of the head is always dark. It is known as the 'garden springtail' and is one of very few Collembola that is regarded as a pest as it is often associated with damaged seedlings. Bourletiella arvalis is a tad larger, averaging around 1.5mm, and has a yellowish coloured body, which can be darker in some individuals, but the lower half of the head is always pale. If I ever get to photograph one of these species I will give it a separate page, but for now I thought it would be useful to include them here for reference as they are so closely related to Deuterosminthurus pallipes.

The question that I'm now trying to understand is how to distinguish these species from photos. I know it's possible if the photos are sharp and show good detail as there are plenty of great images on the internet. The photos currently featured here are not very good as the conditions were not favourable, but now I know that I have these species in the garden I will ensure I get some better shots on a more suitable, less windy, day. In the meantime though, I'm going to see if I can find more information, because at the moment I'm slightly confused. If I'm understanding the 'key' correctly, in Bourletiella the fourth antennal segment (ant.4) has at least seven subsegments, whereas in Deuterosminthurus there are always seven. Whilst that's not particularly helpful, I'm confused as I've seen a comment from Frans Janssens, who is now widely accepted as the leading authority on Collembola, that "in the genus Bourletiella, the fourth antennal segment has between 6 to 8 subsegments" and "in Deuterosminthurus it has 9 -15 subsegments". If that was so, it would obviously make separation of these species a little easier, but the close-up photos I've seen of the antennae show seven, the first slightly longer, then six shorter subsegments.

Notwithstanding the above, Deuterosminthurus pallipes is a common and widespread tiny springtail that could possibly be found at almost any time of the year, but is most active during the warmer months from April to September. Although primarily ground-dwelling, these species are frequently found on the leaves of low-growing bushes and shrubs. There are two distinct colour forms, yellow or orangish-yellow and, the less common, nominate purple form, both of which interbreed producing single coloured offspring. There are no known darker or paler variants. The yellow variety (form repandus) is by far the most frequently seen, probably as its colour makes it more visible. In some literature and records, this form will be referenced as Deuterosminthurus repandus. The colour does not denote the sex as both sexes occur in both colour forms, but they can usually be recognised from their size as the female is slightly larger with a more elongate body. Although, that said, in both sexes the body is more elongated than in the Bourletiella. The males average about 1mm long and have distinctly longer antennae in relation to their body size. The females typically average around 1.3 to 1.6mm. If, by chance, a slightly smaller yellow species is found with two large violet patches of pigment on its back, it will almost certainly be the far less common Deuterosminthurus bicinctus rather than a variant colour form of Deuterosminthurus pallipes.  

The eye-patch includes eight ocelli in a characteristic pattern comprising a central ocellus with a row of three larger ocelli above and four normal sized ocelli below. Additional distinguishing features that you'll be very lucky to see clearly in photos are that the setae on the outer side of the tibiotarsus of the third leg are about the same length and that in the males there are no longer backward-pointing specialised setae at the posterior end of the sixth abdominal segment. These two features eliminate the unlikely chance of Deuterosminthurus sulphureus, which has some distinctly longer setae on the third leg and a pair of specialised, thicker and longer, setae on the its rear end.  Similarly with the female with the setae surrounding the anus all being of uniform length and thickness. And, from a good lateral view, it will be noted that the dorsal anal valve is longer than the ventral valve below.

Deuterosminthurus pallipes are an interesting species to observe as they are very sociable, so you can often find quite a few individuals together and, when they feel the time is right, they have an involved mating ritual that has been well documented, including being featured in the BBC's 'Life in the Undergrowth' series when David Attenborough referred to them as waltzing springtails.

The task now is to try to get some better photos to replace these 'record shots'.

New species added, Jan.25 (v.1)