Neanuridae and Hypogastruridae

As far as I am currently aware, the two Poduromorpha springtail families Neanuridae and Hypogastruridae cannot easily be distinguished from one another based on field photography alone. Rather, assuming the species is not otherwise obvious, details only visible through microscopic analysis may well be needed.

It is notable that this assertion differs with that made by Dallimore and Shaw's (2013) 'Illustrated key to the families of British Springtails (Collembola). According to that key, the choice between families can be made based on the 'distinctiveness' of the head from the thorax. In Neanuridae, it is argued, the head is indistinct, whereas in the other UK Poduromorpha families (Odontellidae, Poduridae, Onychiuridae, Tullbergiidae and Hypogastruridae), the head is distinct.

I am inclined to disagree with Dallimore and Shaw's key here because the 'distinctiveness' of the head from the thorax is not a binary property. Rather, 'distinctiveness' varies considerably along a gradient from 'clearly distinct' to 'clearly indistinct'. It is not a clear-cut matter. Furthermore, not only does distinctiveness appear to differ between species within the two families, it is also likely that distinctiveness can vary between individuals within a species (i.e. intra-specific morphological variation), and even over time for a single individual (based on environmental conditions, whether the springtail is feeding, resting, etc.).

See original discussion on these two observations:

• https://www.inaturalist.org/observations/198764269
• https://www.inaturalist.org/observations/191698747

Publicado el 05 de abril de 2024 por josscarr