ANISOPTERA - DRAGONFLIES

Anisoptera
Notes - Key -References
Back to Odonata Suborders
- Back to Home Page
Page last updated: 01/26/2017

Notes on the Anisoptera

The 113 species of dragonflies so far recorded in Michigan are divided into 7 families and 36 genera. The nymphs of Anisoptera are distinguished from that of Zygoptera by a more robust shape, such that the thorax and abdomen are generally wider than the head, and that respiration chiefly occurs by expansion and contraction of abdominal muscles that move water in and out of the rectal chamber across gills located within this structure. This also permits nymphs to achieve rapid bursts of speed in the water. Nymphs of Michigan Anisoptera inhabit just about every type of aquatic ecosystem in the state, from the largest of lakes to the smallest bog pool, from the very small woodland seeps to the largest of our rivers. Our species of Cordulegaster generally are found only in seeps and streams, and the only species of Petaluridae found in Michigan - Tachopteryx thoreyi - probably is found only in leafy material in the upper portions of forested seeps, and is probably our only odonate that can breathe air (semiterrestrial).

The similarity in morphology among the nymphs of Libellulidae, Corduliidae and Macromiidae has led some to group these as subfamilies in Libellulidae. As of yet, no one morphological character has been found to reliably separate nymphs of Corduliidae from Libellulidae, although characters suggested by Walker and Corbet (1975) and Westfall and Tennessen (1996) - cerci at least 0.5x the length of the paraprocts (Corduliidae), less than 0.5x length (Libellulidae); distal edge of labial palp rather deeply dentate (Corduliidae), shallowly dentate or almost entire (Libellulidae) - works well for most of Michigan's larval species. The status of Macromiidae as a family is not yet clear, and many authorities retain it as a subfamily of Corduliidae (e.g., Westfall and Tennessen 1996). Certain larval (and adult) characters, however, separate these nymphs from both Corduliidae and Libellulidae (see Gloyd 1959). Hopefully a thorough morphological, molecular and ecological study of the entire group will one day resolve the matter.

back to top
Key to the Michigan Families of Anisoptera nymphs
(References: Walker and Corbet 1975, Westfall and Tennessen 1996 and Wright and Peterson 1944)

1a. Mentum flat or nearly so (Fig. 1), without dorsal premental setae (Fig. 2) - 2

Fig. 1Fig. 2
Fig. 1:
Ophiogomphus rupinsulensis larva (6x, lateral view), from the Salmon-Trout River, Marquette County, Michigan, by M. F. O'Brien on 21 June 1997. Fig. 2: Aeshna umbrosa larva, (6x, dorsal view).

1b. Prementum and palpal lobes forming spoon-shaped structure (Fig. 3) - 4

Fig. 3
Fig. 3. Cordulia shurtleffi larva (6x, lateral view), collected from Lake Genevieve (near Ann Arbor), Washtenaw County, Michigan by M. F. O'Brien on 05 April 1998. UMMZODO-1896.


2a.(1a). Antennae 4-segmented, third segment often enlarged (Fig. 4); pro- and metatarsi 2-segmented (Fig. 5); ligula without a median cleft (Fig. 6) - Gomphidae

Fig. 4 Fig. 5 Fig. 6
Fig. 4:
Ophiogomphus rupinsulensis larva (dorsal view, 12.5x), from Salmon-Trout River, Marquette Co., Michigan, collected by M. F. O'Brien, on 21 June 1997, UMMZODO-1972; Fig. 5-6: Dromogomphus spinosus larva (both 12.5x, ventral view), from Third Sister Lake, Washtenaw Co., Michigan, collected by F. Locke in July, 1940, UMMZODO-0562.

2b. Antennae 6- and 7-segmented (Fig. 7); pro- and metatarsi tarsi 3-segmented (Fig. 8); ligula with a median cleft (Fig. 9) - 3

Fig. 7 Fig. 8Fig. 9

Back to beginning of key


3a.(2b). Antennae segments short, thick, and hairy (Fig. 10); prementum with sides sub-parallel in distal three-fifths, abruptly narrowed near base (Fig. 11); a pair of lateral-dorsal abdominal hair tuft present (Fig. 12) - Petaluridae, Tachopteryx thoreyi

Fig. 10Fig. 11 Fig. 12

3b. Antennal segments slender and bristle-like (picture); prementum widest in distal half, then much narrower in basal half or more (picture); abdomen without lateral-dorsal abdominal hair tufts (picture) - Aeshnidae
Back to previous couplet (2); Back to beginning of key


4a.(1b). Distal edge of lateral lobe with large, irregular teeth without associated setae, ligula with a median tooth-like cleft (Fig. x) - Cordulegastridae, Cordulegaster


Fig. x: Cordulegaster maculata larva (6x, ventral view), from Sunset Creek, Iron Co., Michigan, collected by D. Cuthrell and D. Hyde (Michigan Natural Features Inventory) on 14 June 1996. UMMZODO-1576.

4b. Distal edge of lateral lobe entire, or with even-sized dentations, with associated setae (picture); ligula not as above (picture) - 5

Fig. x Fig. x
Fig. x-x:
Libellula luctuosa larva (12.5x, ventral view), from Pond at Clear Creek (Norris Dam), Anderson Co., Tennessee, collected by M. Wright on 21 July 1946. UMMZODO-1994.

Back to beginning of key


5a.(4b). Head with thick, erect frontal horn postitioned between antennae (Fig. x), and metafemur very long, reaching at least to apex of abdominal segment 8 (picture); metasternum with broad, median tubercle (picture) - Macromiidae

Fig. xa Fig. xb Fig. xc
Fig. xa:
Macromia illinoiensis larva (Figs. xa-xb, 6x dorsal view; Fig. xc, 6x ventral view), from an unknown locality in Alpena Co., Michigan, collected by C. L. Hubbs on 30 August 1925. UMMZODO-1219. Fig. xb: Macromia illinoiensis larva (6x, dorsal view), same specimen as Fig. xa. Fig. xc: Macromia illinoiensis larva, (6x, ventral view), same specimen as in Fig. xa.

5b. Head without frontal horn positioned between antennae (Fig. x), and metafemur not reaching apex of abdominal segment 8 (Fig. x); metasternum without median tubercle - 6

Fig. x Fig. x
Fig. xa:
Epitheca spinigera larva (6x, dorsal view), from an unknown locality in Montmorency Co., Michigan, collected by C. L. Hubbs in July, 1925. UMMZODO-0310. Fig. xb: Epitheca spinigera larva (12.5x, dorsal view), same specimen as in Fig. xa.

Back to previous couplet (4); Back to beginning of key


Artificial key (no one character can reliably separate the families Corduliidae and Libellulidae, hence one may have to run through the keys of both families to reliably identify a specimen to genus):

6a(5b). Distal edge of lateral lobe of labium with prominent crenations, usually at least as one-fourth deep as wide (fig); cerci usually at least one-half as long as epiproct (fig); abdomen generally ends abruptly (fig) - 7

Fig. xa Fig. xb Fig. xc Fig. xd
Fig. xa:
Epitheca cynosura larva (25x, ventral view), from Hess Pond, Columbus, Franklin Co., Ohio, collected by M. Wright on 26 May 1939. UMMZODO-2015. Fig. xb: Epitheca cynosura larva (12.5x, dorsal view), same specimen as in Fig. xa. Fig. xc: Neurocordulia yamaskanensis larva (6x, dorsal view), from Paint River, Iron Co., Michigan, collected by D. Cuthrell and D. Hyde on 19 June 1996. UMMZODO-1783. Fig. xd: Epitheca cynosura larva (12.5x, dorsal view), specimen as in Fig. xa.

6b. Distal edge of lateral lobe of labium generally with crenations less than one-fourth as wide, or obsolete (fig. xa); cerci usually less than one-half as long as epiproct (fig. xb); abdomen distally more tapered (fig) - Libellulidae

Fig. xa Fig. xb Fig. xc
Fig xa-c:
Libellula luctuosa larva (6x, dorsal view), from Pond at Clear Creek (Norris Dam), Anderson Co., Tennessee, collected by M. Wright on 21 July 1946. UMMZODO-1994. Fig. xb: Libellula luctuosa larva (12.5x, dorsal view), same specimen as in Fig. xa. Fig. xc: Libellula luctuosa larva (12.5x, dorsal view), same specimen as in Fig. xa.

Back to previous couplet (5); Back to beginning of key


7a. Lateral spine of Ab8, when present, shorter than middorsal length of Ab9 (Fig. x) - Corduliidae

Fig. x
Fig. x: Epitheca spinigera larva (6x, dorsal view), from an unknown locality in Montmorency Co., Michigan, collected by C. L. Hubbs in July, 1925. UMMZODO-0310.

7b. Lateral spine of Ab8 as long as middorsal length of Ab9, or longer (Fig. x) - Libellulidae, genus Pantala

Fig. x
Fig. x:
Pantala hymenea larva (6x, dorsal view), from Marble Cliffs Pond, Columbus, Franklin Co., Ohio, collected by M. Wright on 03 August 1939. UMMZODO-1540.

Back to previous couplet (6); Back to beginning of key

back to top
References

Gloyd, L. K. 1959. Elevation of the Macromia group to family status (Odonata). Entomological News 70(8):197-205.

Walker, E. M., and P. S. Corbet. 1975. The Odonata of Canada and Alaska, Vol. 3. University of Toronto Press: Toronto. xvi + 308 p.

Westfall, M. J., Jr. and K. J. Tennessen. 1996. Odonata, pp. 164-211. In An Introduction to the Aquatic Insects of North America, 3rd Ed. R. W. Merritt and K. W. Cummins (eds.) Kendell/ Hunt Publishing Company: Dubuque, Iowa.

Wright, M., and A. Peterson. 1944. A key to the genera of Anisopterous dragonfly nymphs of the United States and Canada (Odonata, Suborder Anisoptera). Ohio Journal of Science 44(4):151-166.

back to top