GOMPHIDAE -Clubtails

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Page last updated:23 October 1998 (EB)
Notes on the Michigan Larvae of Gomphidae

Michigan's second largest family ofdragonflies, 31 species in 8 genera have so far been recorded in ourstate. The taxonomic status of one genus, Gomphus, continues to bedisputed. Erpetogomphus has not yet been recorded in Michigan, but a recordfrom central Ohio may make it possible that it can be encountered inthe southernmost part of our state.

Although adults are referred to as "clubtails,"as the abdomen is often enlarged posteriorly to resemble a club,gomphids could just as easily be called "burrowing dragonflies," inreference to the larval habit of burrowing into various substrates inlotic and lentic waters. Their larval morphology - reduced antennaesegments and strong fossorial legs, among other morphologicaladaptations - is ideally suited for concealing themselves insubstrate and loose particulate debris. It's very interesting towatch live captured individuals, when released or put into acontainer filled with silt, sand or other debris, quickly use theirlegs to conceal themselves. Most are found in silt, sand or gravel inlakes and rivers, but one species - Hagenius brevistylus - hasadapted itself to conceal itself by sprawling within leafy and woodydebris in streams and lakes.

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Generic Key to Mature Larvae of MichiganGomphidae

1a. Mesocoxae closertogether than procoxae (Fig.1a1); Ant4 elongate, 0.25x as long asantennal segment 3 (Fig.1a2) - Progomphusobscurus
Fig. 1a1Fig.1a2

1b.Mesocoxae not closer together than procoxae (picture); antennalsegment 4 vestigial or a small, rounded knob (picture) -2

2a.(1b). Abdomen subcircular, body very flat (Fig. 2a1);head with paired tubercles behind eyes (picture) - Hageniusbrevistylus

2b.Abdomen not so flat, more cylindrical (picture); head without pairedtubercles behind eyes (picture) - 3
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3a.(2b). Wing cases strongly divergent (Fig. 3a1); Ab8 and9 about equal in middorsal length; lotic - 4

Fig. a
Fig. 3a1:
Ophiogomphusrupinsulensis larva, 12xdorsal view. Specimen collected from the Salmon-Trout River,Marquette County, Michigan, by M. F. O'Brien on 21 June 1997.

3b. Wing casesparallel along back (picture); middorsal length of Ab9 clearly longerthan that of Ab8 - 5
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4a.(3a). Epiproct, cerci and paraprocts all subequal inlength (picture) - Erpetogomphusdesignatus

4b. Cercidistinctly shorter, at most 0.8x the length of the epiproct andparaprocts (Fig. 4b1) - Ophiogomphus

Fig. 4b1:
O.susbehcha exuvia (12.5x,lateral view), from St. Croix River, Burnett Co., WI, collected by T.E. Vogt on 30 May 1990.

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5a.(3b). Flattened antennal segment 3 nearly oval (Fig.5a1); lotic - Stylogomphusalbistylus

Fig. x.
Fig. 5a1. Stylogomphusalbistylus larva,collected fromMountain Stream, Marquette Co., Michigan, USA, on 30 June 1996 byBright, O'Brien and M. A. Kielb. UMMZODO-0179.

5b.Cylindrical antennal segment 3 more than 4 times as long as wide(picture) - 6
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6a.(5b). Abdominal segment 9 with a long acute middorsalridge ending in a long, sharp apical hook usually markedly darkerthan body base color (Fig. 6a1), ridge raised in lateral view (Fig.6a2) - Dromogomphusspinosus

Fig. 6a1 Fig.6a2
Fig. 6a1: Dromogomphusspinosus larva (12x, dorsalview), collected from Third Sister Lake, outside Ann Arbor inWashtenaw County, Michigan, by F. Locke, on July 1940.UMMZODO-0562.
Fig. 6a2: Ibid, lateral view. Both images taken at 12x.UMMZODO-0562.

6b. Abdominalsegment 9 without such an acute, dark middorsal ridge bearing dorsalhook at apex (picture), and usually not markedly raised in lateralview (picture) - 7
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7a.(6b). Pro- and mesotibiae with burrowing hooks absent orobsolete (picture); lotic - Stylurus

7b. Pro- andmesotibiae with burrowing hooks at outer apical angle about as longas width of tarsus (picture) - 8
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8a.(7a). Abdominal segment 10 longer than wide (Fig. 8a1-2)- Arigomphus

Fig 8a1: Arigomphus cornutus exuvia, (12.5x, dorsal view) from Washtenaw Co.,Michigan, collected 23 May 1998 by M. F. O'Brien.

8b. Abdominalsegment 10 wider than long (picture) - Gomphus complex
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