Adaptations for walking on plants

I would argue, the most under-appreciated niche among Aleocharinae are the myriad of associations with plants. Naturalists wouldn’t associate aleocharines and probably staphylinids in general as being associated with plants, but of course, the ecologically promiscuous aleocharines have managed to evolve plant-associations multiple times. Although they never really take off in number of species, the ways they associate with plants are rather intriguing.

There are those that eat pollen, such as Platandria, Microlia, Amazoncharis, Polylobus, Oxypodinus, Heterotaxus. Himalusa eats foliage. There are some stranger ones still that are predaceous in the confines of inflourecsens and leaf rolls, such as Charoxus, Ctenopeuca, Heliconandria, and Polycanthode. And then those that seem to be openly predaceous on foliage, like Oligota and Leucocraspedium Leucocraspedum (thanks go out to Margaret for pointing out the spelling error for the genus).

Below I quickly put together some adaptations that you can find on the fore leg morphology of plant-associated aleocharines.

Adaptations in the fore leg of Aleocharinae associated with plants.

Adaptations in the fore leg of Aleocharinae associated with plants.

Spines appear to be a popular theme in aiding with grip on a smooth surface, as can be seen in the pollen feeding Amazoncharis and Heterotaxus. Notice that Amazoncharis has stubby modified setae on the ventral surface of its tarsus in addition.

Heliconandria peoechma, on the other hand, lives in the leaf and flower rolls of Heliconia spp. Here, they likely prey on soft bodied organisms and participate in lapping up biofilms for microscopic food items. This species has additional fuzziness on the basal-most tarsomere and a modified tarsal claw. The tarsal claw is ventrally swollen, and has an additional facet which adds surface area.


5 responses to “Adaptations for walking on plants

  1. Grey Gustafson

    Stenus ……. you should probably work on Stenus

  2. Margaret Thayer

    How do you figure that spines on the surface of the tibia are involved in getting traction on surfaces? Ventral tarsal modifications (widened setae, pad-like structures) are reasonably well-documented in that regard. Another flower-frequenter is Pagla; I don’t know if it has any tarsal modifications. The pad you show in Heliconandria is reminiscent of Neophonus.
    P.S. Leucocraspedum (no “i” in it)

    • taroeldredge

      Pagla does have tarsal modifications! The tarsomeres are slightly ventrally lobed and have longer more delicate setae that grow from their venters. Aleocharinae never really seem to develop the characteristic spatulate setae nore elaborate pads-they seem to be all about simplicity. So you end up with repeated evolution of spines and slight tarsal modifications and nothing as elaborate as other staph subfamilies.

      Interestingly, spines and simple tarsal stubble seem to be the catch all solution for locomotion in aleocharines. Lineages that have invaded sandy substrates (riparian, beach) also develop such structures repeatedly.

      You’re right about Neophonus! Thanks for the reminder, haven’t read your pub in a couple years! The idea is similar, additional sides for expanded surface area I suppose. Not to mention the foliage surface habitat is similar.

      Thanks for the spell check. Gotta fix that.

  3. Amazoncharis

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