Ptenothrix maculosa

The species is described in terms of microscopic features that are unique, such as the arrangement and size of setae on the small abdomen at the posterior of the body, as well as relative lengths of certain setae on the tip of the furca (the jumping organ). Over time several visual patterns have been noted that will distinguish this species in photos, compared to other species found in the same locations. This photo identification has been critical for citizen science sites such as iNaturalist, to gain insight into the geographical range of the species.

This species is a common woodland species, ranging from Alaska to California. It is commonly found under rotting wood, and in and under leaf litter, where it plays the roll of a decomposer in natural areas. Ptenothrix maculosa is classified as native to, and likely endemic to North America.

This species is extremely variable and has many color forms. Due to lack of microscopy, at least four other species of springtails have been mislabeled under its name. Some of the west coast springtails that were misidentified as Ptenothrix maculosa were Ptenothrix delongi, Ptenothrix beta, and Ptenothrix californica. Microscopic keying by citizen scientists across the west helped to find out the real maculosa, which had been labeled under "Undescribed Ptenothrix" by Belgian taxonomist Frans Janssens. Another misconception within the community was that the summer colour-pattern of Ptenothrix maculosa, which were misidentified as Ptenothrix palmata (a separate west coast species of springtail noted as being similar, and associated with alpine and arctic habitats). This was also proven false after multiple specimens keyed out to Ptenothrix maculosa. There was another misidentification done via pattern for this species as Ptenothrix marmorata (an east coast species of Ptenothrix) in 2021, which is thankfully the only of its kind. Another form of Ptenothrix maculosa that remained unidentified for some time was one listed on collembola.org as "Ptenothrix Species 4". Frans Janssens had conjectured that due to the different colour pattern, this may be a new species. Eventual microscopic identification showed that it was a color-pattern variant of P. maculosa. …