Corresponding author: Mark A. Metz (
Academic editor: Y. Mutafchiev
We explore and expand on the morphological term digitule. The term was originally proposed for toe-like setae on a species of
Metz MA, Miller DR, Dickey AM, Bauchan GR, Ochoa R, Skvarla MJ, Miller GL (2017) Rediscovering digitules in Aphidomorpha and the question of homology among Sternorrhyncha (Insecta, Hemiptera). ZooKeys 683: 39–50.
The hemipteran suborder
The genus
All of the dictionaries and texts on entomology we checked define digitule with a similar rendition of the same phrase, and are possibly or known to be non-independent repetitions. For example:
The Dictionary of Entomology (
External Insect-anatomy: A Guide to the Study of Insect Anatomy and an Introduction to Systematic Entomology (
The Dictionnaire des Termes D'Entomologie (
The Torre-Bueno Glossary of Entomology (
A Dictionary of Entomology (Gordh 2001, 2011):
All the above descriptions associate the term digitule with
*
The adoption of digitule to describe toe-like setae at the terminus of the legs in
In contrast, the scientists with the most impact studying
AMD collected galls of presumably undescribed species of
We also obtained color images and videos of specimens in situ using a Hirox KH-7700 Digital Microscope (Hackensack, NJ) with a MXG-5040RZ lens to assess locomotion. The digital microscope has a motorized stage which allows the capture of several images at 1600×1200 pixels per frame with varying degrees of focus, which were compressed together to develop an image where all fields of view are in focus. We recorded video at 800×600 pixels per frame at 15 frames per second. We collected this imagery before freezing as reference material for observations made with the LT-SEM. MAM reproduced
Three distinct
Based on
Digitules seem pliable as they are commonly bent when in contact with the substrate even though in some images the substrate seemed soft enough to take an impression from the digitules and tarsal claws. We did not observe any consistency of position of digitules and claws in relation to specimen activity to make any determinations of their function, and could not indisputably determine that any specimens were in locomotion at the time of freezing. Most specimens with their feet in contact with substrate also had their rostrum embedded in the gall inner wall (Fig.
Through attempts to observe the interaction of
The use of the term digitule is prevalent in coccidomorph literature, and is confounded by the lack of distinction between shape and positional homology as we mentioned above. All taxa among
So what, if anything, can we recommend to progress towards a stable solution? Testing homology across all of
The authors wish to thank Colin Favret, Université de Montréal, Quebec, Canada for helpful discussions and comments. Mention of trade names or commercial products in this publication is solely for the purpose of providing specific information and does not imply recommendation or endorsement by the USDA; USDA is an equal opportunity provider and employer.