The "Obvious" Table

Below is a table of a number ofodonate larvae that have very distinctive and visible characters andshapes, thus allowing one to avoid sequential use of the dichotomouskeys and quickly zero in on the taxa in question. If you are certainthat the specimen in hand looks exactly like the individualrepresented in the table below, just click on the image and you willbe brought to the corresponding page for that taxa.

Certain species are simply obvious. For example,
Hagenius brevistylus looks like no other odonate larvae inMichigan. Clicking on the image will allow you to bypass three stepsin the dichotomous key: suborder, family and genus/species. Anotherexample is the damselfly larvae of the family Calopterygidae,distinctive for their elongated first antennal segment. However,careful examination usually with a microscope is required for mosttaxonomic distinctions, especially for closely related genera andalmost all species.

CAUTION!Several words of caution. First, this works best if one has on handmature larvae. Many diagnostic larval characters change over thedevelopmental course of larval instars. Second, make sure that youhave undamaged and relatively clean specimens with which to compare.And third, don't take a "plug-and-chug" approach to taxonomy. Untilwe have diagnostic character tables complete (time and funding!!!) tocompare taxonomic criteria, is best to back up to a key and run yourspecimen through the key. Remember, these characters are based ontaxonomic information collected from researchers over the lasthundred or so years, but our knowledge on many species is stilllacking and incomplete. If something doesn't necessarily fit, itcould be natural variation within a species that has yet to bereported, it could be the result of hybridization, or, indeed, itcould be a new species. Still, there are certain characters that arejust simply obvious, so...


Zygopera (picture)

Anisoptera (picture)

Calopterygidae - elongated 1st antennal segment(picture)

Lestidae, Lestes - elongated mentum that extend backthrough the metacoxae (picture)

Petaluridae, Tachopteryx theoryi (picture)

Cordulegastridae, Cordulegaster (picture)

Gomphidae (picture)

Hageniusbrevistylus(Gomphidae) - abdomensemi-circular and very flat (picture)

Stylogomphusalbistylus (Gomphidae) -oval 3rd antennal segment with straight inner margin (picture)

Progomphus obscurus (Gomphidae) - mesocoxae narrower togetherthan procoxa, elongated 4th antennal segment (picture)

Nasiaeschna pentacantha(Aeshnidae) - low medianridge on dorsum of abdomen with blunt hooks (picture)

Macromiidae - long hind leg, hindfemur reaches abdominal segment 8 (picture)

Erythemissimplicicolis(Libellulidae) - cerci and paraprocts decurved to tip(picture)