| Ptenothrix | |
|---|---|
.jpg) | |
| Ptenothrix beta | |
Scientific classification  | |
| Kingdom: | Animalia |
| Phylum: | Arthropoda |
| Clade: | Pancrustacea |
| Class: | Collembola |
| Order: | Symphypleona |
| Family: | Dicyrtomidae |
| Subfamily: | Ptenothricinae |
| Genus: | Ptenothrix Boerner, 1906 |
Ptenothrix is a genus of globular springtails in the family Dicyrtomidae. There are about 92 described species in Ptenothrix worldwide.
This genus is very diverse with many different color parterns. Many species vary in pattern and so sometimes microscopy can reveal that visually different specimens are conspecific. Some species have mottled abdomens like Ptenothrix delongi, while others such as Ptenothrix alveola are checkered, but are relatively consistent in appearance. Others can have completely different colors altogether as in the case of Ptenothrix maculosa. Some species are more uniform in coloration over the whole body, like Ptenothrix unicolor and Ptenothrix atra. Though many experts are able to identify specific species by color pattern, to confidently identify Ptenothrix you generally need more than just color, you also need to pay attention to the tip of the antenna, which is prominent and not usually hairy, shoulder hairs, hairs near the back, and a hunched back.
The genus is defined by a cluster of traits, most pertaining to chaetotaxy. These traits are as follows: large abdomen without a protuberance, with a full set of bothriotricha and posteriorly covered with small acanthoid chaetae, head and abdomen with at least some large acanthoid chaetae, hind tibiotarsus with 2–3 modified serrated chaetae, claws usually with no tunica, outer and inner chaetae on the dens often serrated, and no neosminthuroid chaetae.
There is a lot of outdated information on Ptenothrix species. The way that these species were originally described and identified was via chaetotaxy. Springtail expert Frans Jessans decided to attempt to create a website that tracked every springtail called Collembola.org. He decided to create a website to visually identify every species of springtail on earth. the result was a lot of different lists of just pictures on the website with the rare comment or two on some species. The issue was that without the original chaetotaxy being done before identification, he accidentally described a lot of species of Ptenothrix as undescribed based off their pattern. In 2021 a group of citizen scientists used microscopy to discover that all the species that Frans called undescribed were in fact different patterns of the variable species Ptenothrix maculosa. Additionally Frans had placed Ptenothrix beta, Ptenothrix delongi, and Ptenothrix californica in many cases in under the species name of Ptenothrix maculosa. the result was that various citizen scientists across the Pacific Northwest had to use The Collembola of North America, North of the Rio Grande: A Taxonomic Analysis - 4 Volumes, the book set that the west coast species were all redescribed in. After 2 years of keying the species, eventually the different species taxonomy was updated to what the original keys said.
Sage Osterling has since created a website called Mesofauna of the Pacific Coast, peer reviewed by other members of the community that have keyed out these species. It is used as a better resource for west coast springtails than Collembola.org since it has descriptions and citations that the latter does not generally display. It can be used as resource outside of Wikipedia for accurately visually identifying Ptenothrix species, in reference to the microscopy.
Bugguide records are out of date since the main springtail expert on the site in the early 2000s to the 2020s was Frans himself. Collembella.org is also now just used by the community as reference material.
the true key to these species is the The Collembola of North America, North of the Rio Grande: A Taxonomic Analysis - 4 Volumes which was written by Christiansen and Bellinger, the former experts on west coast springtails. It contains keys that the springtail community uses to key out various species, especially Ptenothrix species and many others.
The genus Ptenothrix was formally described by Carl Julius Bernhard Börner in 1906. The original species were originally placed in Papirius (Lubbock, 1862) and Dicyrtoma (Bourlet, 1842).
These species belong to the genus Ptenothrix:
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