Cordulegastridae Calvert
Cordulegaster Leach, 1815 - Spiketails

Fig. 1: General lateralprofile of a Cordulegastermaculata larva, drawn byElizabeth Anderson

Notes -Michigan SpeciesList - Key -References
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Page last updated: 20August 1998 (EB)

Notes onthe Michigan Species of Cordulegaster

This is a widespread family of dragonflies.Five of the eight species of Cordulegaster found inNorth America have been recorded in Michigan (see maps below).

Cordulegasteras a group is currently under considerable dispute, despite severalattempts over the past two decades (e.g., Carle 1983, Lohmann 1992) to construct monophyletic groupings among speciestraditionally placed in this genus. In describing Zoreana bilineata,Carle(1983) elevates to genus the subgeneraCordulegaster (or Thecophora),Taeniogaster and Zoraena. Going evenfurther, Lohmann(1992) argues that Cordulegaster is an OldWorld genus, and that the North American species are surviving andindividual remnants of formerly speciose, distinct ancient groups. Hegrouped the eight North American species into the six genera.However, many researchers - especially in North America - arereluctant to accept these proposals (but see May and Carle1996), and we follow the conservativepractice of relegating Taeniogaster,Thecophoraand Zoraena as subgenera of Cordulegaster (e.g.,Westfalland Tennessen 1996). The table belowsummarizes the placement of Cordulegasterspecies:

Species

North American
Distribution

Westfall and Tennessen 1996
subgenera

Carle 1983
genera

Lohmann 1992
genera

C. obliqua

East

Taeniogaster

Taeniogaster

Taeniogaster

C. bilineata

East

Zoraena

Zoraena

Zoraena

C. diastatops

East

Zoraena

Zoraena

Zoraena

C. sayi

Southeast (FL, GA)

Zoraena

Zoraena

Archegaster

C. diadema

West; also C. America

Thecophora

Cordulegaster

Lauragaster

C. dorsalis

West

Thecophora

Cordulegaster

Lauragaster

C. erronea

East

Thecophora

Cordulegaster

Kalyptogaster

C. maculata

East

Thecophora

Cordulegaster

Panaeagaster

Except for C.bilineata and C. diastatops, separationof the Michigan species of Cordulegaster isrelatively straightforward. For those two species, however, nomorphological description has been published that will separate thetwo species. In fact, thereis considerable dispute whether C. bilineata is sufficiently distinct from C. diastatops to be regarded as a separate species.The larval forms appear very similar and may, in fact, not bedisguishable from each other. Although the two species usually do notoccur together ( Carle 1983), both species have been found in thesame habitat in the northern part of its range. It is highlyrecommended that any pre-emerging larvae be reared and identificationbased on the adult form. I (EB) am currently trying to obtainspecimens of both species to determine if there are larval charactersthat distiguish the two. In lieu of any peered-reviewed publishedinformation, I would label collected larvae lacking associated adultmaterial of these two species as "C. diastatops or bilineata".

C. erronea isappears to be very rare in Michigan, and only one record appears tohave been reported from the western part of the LP. This is mostly asouthern species, and Michigan probably represents the northernmostpart of its range. This species is on the State's Special Concern List. In Hocking Co., south-central Ohio, C. erronea inhabits sandsubstrates of forested seeps and spring-fed brooks with considerableslope (Dan Riggs, pers. comm.). C.obliqua tends to be found only infirst-order, small sandy forest brooks, at least in the southern partof its range (Tennessen et al. 1995). Based on observations of adultC. bilineata and C.diastatops in Michigan, habitat tendsto be sandy substrates of downstream pools and runs of hillsidesprings and brooks, both in forested as well as open or bushypastures. This appears to agree with habitat descriptions for thesespecies from other workers (e.g., Walker 1958, Tennessen et al.1995). The rarity of specimens (particularly larvae) from our statereflects insufficient sampling of these habitats. Conversely,C. maculata (Figure 1), which inhabits larger forested creeks andstreams with good water quality, is by far Michigan's (and EasternNorth America's) most common cordulgastrid and is found throughoutthe state.

Larvae usually are found submerged under sandand silt, often protected under pieces of large woody or leafydetritus where they lie in wait for prey. Larvae are long-lived andprobably require over three years in which to develop into adults, atleast in the northern part of its range: three different size classesof larval C. maculata have been found in streams from Marquette Co., UP (EB,pers. obs.). Emergence of this species in the north appears to occurin early to mid-June, with females observed ovipositing in earlyJuly. Kennedy(1917) collected four size classes ofC. dorsalis in California. Emergence occurs close to the watersedge, usually in June. Johnson (1982) studied prey selection of C. maculata from a streamin the Adirondack Mountains in New York, USA., and found thatmayflies (Baetis sp. and Paraleptophlebia sp.) werethe principal prey, with chironomids, simulids and caddisflies ofvarious trophic relationships also important components. The authorspeculated that C. maculatain this stream are active foragers(apparently at night), as their principal prey (in this study, themayflies) where not well represented in Surber samples that were usedto collect larvae in the deeper sections of the stream.Unfortunately, the author did not account for drift in prey species,thus the observation must be considered speculative.

Other links with information on the biology orecology of larval Cordulegaster (checked on12 August 1998):
Cordulegastersayi ESA status>>http://www.epa.gov/docs/fedrgstr/EPA-SPECIES/1994/October/Day-26/pr-24.html
Biologyof C. sayi >> http://www.ims.usm.edu/~musweb/sayi.htm
Ottawa,Ontario survey, with brief habitat notes >> http://www.cyberus.ca/~jdsankey/odon2.html
UKCordulegaster boltoni >>http://www.ex.ac.uk/~cnfrench/ics/cbru/monitor/corbol.htm

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MichiganSpecies List

Map1Map2Map3
Map4Map 5
Maps 1-5: County distribution of the Michigan species of
Cordulegaster
Click on map for a larger image

Cordulegaster (subgenus Zoraena) bilineata (Carle, 1983) - Brown Spiketail - Map 1
Cordulegaster
(subgenus Zoraena) diastatops (Selys, 1854) - Delta-spotted Spiketail - Map 2
Cordulegaster
(subgenus Thecophora)erroneaHagen in Selys,1878 - Tiger Spiketail - Map3
Cordulegaster
(subgenus Thecophora)maculataSelys,1854 - Twin-spotted Spiketail - Map4
Cordulegaster
(subgenus Taeniogaster)obliqua(Say,1839) - Arrowhead Spiketail - Map5

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Key to Mature Larvae ofMichigan Cordulegaster
(Based on Walker 1958, Carle1983, Westfall and Johnson (unpublishedinformation), and pers. obs.)
Thanks to Bill Maufrey of IORI for a generous loan ofspecimens.

1a. Prementum wider atbase, palpal width < 2.4x that of basal width (Figure 1a1);frontal shelf truncate in dorsal view (Figure 1a2), subacute inlateral view; lateral spines of Ab8 strongly upcurved (Figure 1a3);developing ovipositor of female about 0.7x length of Ab9 sternum(Figure 1a4) - C.diastatops or C. bilineata

Fig.1a1Fig. 1a2
Fig. 1a3Fig. 1a4
Fig. 1a1:
C.diastatopslarva, collected from Belchertown, MA, on 12 May 1938. leg. J.Needham? IORI loan.
Fig. 1a1-2: Ibid., 12.5x, dorsal view.
Fig. 1a3: 12.5x, lateral view.
Fig. 1a4: 6x, ventral view.
1b. Prementum narrower at base,palpal width > 2.5x that of basal width (Figure 1b1); frontalshelf appearing rounded in dorsal view (Figure 1b2), acute andridge-like in lateral view; lateral spines of Ab8 not so stronglyupcurved (Figure 1b3); developing ovipositor of female 0.9x or morethe length of Ab9 sternum (Figure 1b4) - 2

Fig.1b1Fig.1b2
Fig.1b3Fig.1b4
Fig. 1b1: C.erronea larva (12.5x, ventralview), from Camp Carding, Brevard, NC, collected by M. J. Westfall inAugust 1942. IORI loan.
Fig. 1b2:
C.maculata larvae (12.5x dorsalview), from Packer Creek, Montmorency Co., MI, collected by D.Cuthrell and D. Hyde (MNFI) on 25 June 1996.
Fig. 1b3:
C.erronea larva (12.5x, lateralview), from Camp Carding, Brevard, NC, collected by M. J. Westfall inAugust 1942. IORI loan.
Fig. 1b4:
C.maculata larva (12.5x,ventral view), from Packer Creek, Montmorency Co., MI, collected byD. Cuthrell and D. Hyde (MNFI) on 25 June 1996.


Note: some specimens ofC.maculata may have 4 or6 palpal setae on one palpal lobe (feeding accidents or developmentflaws?), but almost always 5 setae on the other lobe. In this case,refer to the character on premental setae to determinespecies.
2a(1b). Palpal setae 6-7,premental setae 12 or more (usually 8+6) (Figure 2a1); developingovipositor of female about 0.9x length of sternum of Ab9 -C.(Taeniogaster) obliqua

Fig.2a1
Fig. 2a1:
C.obliqua exuvia (12.5x, dorsalview), locality and collector information missing. IORI loan.

2b. Palpalsetae 4 or 5, premental setae 11 or less (usually 5-6+4-5) (Figure2b1); developing ovipositor of female > 1.0x length of sternum ofAb9 (Figure 1b4) - 3

Fig.2b1
Fig. 2b1:
C.maculata larva (12.5x, dorsalview), from Packer Creek, Montmorency Co., MI, collected by D.Cuthrell and D. Hyde (MNFI) on 25 June 1996. UMMZODO-1393.

Back to previouscouplet(2); Back to beginning ofkey


3a(2b). Lateral setae 4 (Figure 3a1); few but largeobsolescent brown dots on frontal shelf (Figure 3a2); epaulets evenlyrounded in dorsal aspect (Figure 3a3) - C. (Thecophora)erronea

Fig. 3a1Fig. 3a2
Fig. 3a3
Fig. 3a1:
C.erronea larva (12.5x, dorsalview), from seepage ditch in Monroe Co.,TN, collected by K. J.Tennessen on 24 July 1979. IORI loan.
Fig. 3a2:
C.erronea larva (12.5x, dorsalview), from Highlands, NC, collected by M. J. Westfall on 22 June1953. IORI loan.
Fig. 3a3:
C.erronea larva (12.5x, dorsalview), from Camp Carding, Brevard, NC, collected by M. J. Westfall inAugust 1942. IORI loan.

3b. Lateralsetae 5 (Figure 3b1); small round dots numerous, occupying ca. 1/2the area of the frontal shelf (Figure 3b2); epauletsanteriorlaterally truncated in dorsal aspect (Figure 3b3) -C. (Thecophora) maculata

Fig. 3b1Fig. 3b2
Fig. 3b3
Fig. 3b1:
C.maculata larva (12.5x, dorsalview), from Packer Creek, Montmorency Co., MI, collected by D.Cuthrell and D. Hyde (MNFI) on 25 June 1996. UMMZODO-1393.
Fig. 3b2: Ibid.
Fig. 3b3: Ibid.
Back to previouscouplet(2); Back to beginning of key

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References

Carle, F. L. 1983. A new Zoraena (Odonata:Cordulegastridae) from Eastern North America, with a key to the adultCordulegastridae of America. Annals ofthe Entomological Society of America76(1):61-68.

Johnson, J. H. 1982.Diet composition and prey selection of Cordulegaster maculataSel. larvae (Anisoptera: Cordulegasteridae). Notulae Odonatologicae1(9):151-153.

Kennedy, C. H. 1917.Notes on the life history and ecology of the dragonflies (Odonata) ofcentral California and Nevada. Proceedings of the United States Museum 52:483-635.

Leach, W. E. 1815.Entomology, pp. 52-172. In Brewster's Edinburghencyclopaedia. Vol. 9. Edinburgh.

Lohmann, H. 1992.Revision der Cordulegastridae. 1. Entwurf einer neuen Klassifizierungder Familie (Odonata: Anisoptera). Opuscula Zoologica Fluminen 96:1-18.

May, M. L., and F.L. Carle. 1996. An annotated list of the Odonata of New Jersey, withan appendix on nomenclature in the genus Gomphus. Bulletin of American Odonatology 4(1):1-35.

Say, T. 1839.Descriptions of new North American neuropterous insects andobservations on some already described by (the late) Th. Say.Journal of the Academy of NaturalScience of Philadelphia 8:9-46.

Selys Longchamps, M.E. de. 1854. Synopsis des Gomphines. Bulletin de l'Académie EntomologiqueBelgique 21:23-114.

Selys Longchamps, M.E. de. 1878. Quatriemes Additions au Synopses des Gomphines Bull.Bulletin de l'Académie EntomologiqueBelgique 28:658-698.

Walker, E. M. 1958.The Odonata of Canada and Alaska, Vol. 2. University of TorontoPress: Toronto.

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

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