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ARS Home » Northeast Area » Beltsville, Maryland (BARC) » Beltsville Agricultural Research Center » Systematic Entomology Laboratory » Research » Publications at this Location » Publication #331653

Title: Rediscovering digitules in Aphidomorpha and the question of homology among Sternorrhyncha (Insecta: Hemiptera)

item Metz, Mark
item MILLER, D. - Retired ARS Employee
item Dickey, Aaron
item Bauchan, Gary
item Ochoa, Ronald - Ron
item SKVARLA, M. - University Of Maryland
item Miller, Gary

Submitted to: ZooKeys
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/21/2017
Publication Date: 7/6/2017
Publication URL:
Citation: Metz, M., Miller, D.R., Dickey, A.M., Bauchan, G.R., Ochoa, R., Skvarla, M.J., Miller, G.L. 2017. Rediscovering digitules in Aphidomorpha and the question of homology among Sternorrhyncha (Insecta: Hemiptera). ZooKeys. 4276(1):139-144.

Interpretive Summary: This research explores and expands our knowledge of a morphological term, digitule, created to describe specialized hairs on the legs of gall-forming aphids. These specialized hairs also occur on species of scale insects and the term was adopted by scientists studying that group. Ironically the term was lost to scientists studying aphids, the group for which the term was first created. Based on the history of the scientific literature, this was a cultural event rather than a science-based decision. Aphids and scale insects are closely related and significant pests on many of the World’s agriculturally important plants. So, it is important that we understand the relationships among the species in these two groups and the clarity of the anatomical terms used to describe and diagnose these species. This information will be important and beneficial to the entire scientific community studying scale insects and aphids.

Technical Abstract: We explore and expand on the morphological term digitule. The term was originally proposed for toe like setae on a species of Phylloxera (Hemiptera, Sternorrhynca, Aphidomorpha) by Henry Shimer, an American naturalist. While it is standard terminology in scale systematics (Hemiptera, Sternorrhynca, Coccidomorpha), the term digitule was ignored by aphid specialists despite being the original taxon for which the term was described. Similar setae occur on many arthropod groups, so the homology is poorly understood even within any superfamily of Hemiptera. We provide the etymology of the term, a proposed explanation for why it was used among scale systematists and not aphid systematists, and discuss briefly options to progress beyond the confusion between terminology for morphology and homology in Sternorrhynca.