Notes - Michigan Species List - Key - References
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Page last updated: 11 March 1999 (EB)
Notes on the Michigan Species of Coenagrion and Enallagma
Enallagma is a widespread genus of coenagrionids that is most speciose in North America, with16 species now recorded in Michigan. Coenagrion is chiefly a palearctic genus in which three species occur in North America, with 2 two species occuring here. Larvae are diagnostically a difficult group of damselflies. Only mature specimens with intact caudal gills can be identified to species, and the works (Walker 1953; Westfall and May 1996) upon which the key below is based caution about the reliability of keys. These moderate-sized damselflies closely resemble the larvae of Ischnura and Coenagrion, and diagnostic keys (Walker 1953, Westfall and May 1996) upon which our key is based distinguish Coenagrion and Enallagma only at the species-level.
There is considerable debate regarding the viability of E. vernale Gloyd (1943), which Donnelly (1989) synomized with E. cyathigerum. Recent information and examination of material as well as data from habitat separation (the former inhabit lakes and rivers, the later principally bogs and heavily vegetated ponds) may indeed support the distinct identity argued for by Gloyd. Refer to Walker (1953) to distinguish between these two.
Most species inhabit lakes, ponds and wetlands as well as slower portions of streams and rivers, usually with abundant aquatic vegetation. E. anna, E. aspersum, E. basidens, E. divagans, and E. traviatum are known only from the LP. Both E. anna and E. basidens appear to be expanding their ranges throughout North America, being found in sheltered coves and edges of large lakes, small ponds and slow portions of streams, as well as human-impacted habitats such as impoundments and quarry ponds (Cannings 1989, O'Brien and Pratt, in press). E. antennatum, E. exsulans, E. geminatum, E. signatum and E. vesperum are known in the UP only from one record, but are widespread in the LP. The other species (E. boreale, E. carunculatum, E. civile, the circumpolar E. cyathigerum, E. ebrium, and E. hageni) are widespread in both peninsulas. (See maps below).
Population cohorts for several species have been studied, though little generic-level concensus has been reached. Baker and Clifford (1982) studied a population of E. boreale in a boreal forest pond in Alberta, Canada, and concluded that low temperatures during egg development strongly influenced subsequent growth of larvae, ultimately determining if there were one or two cohorts per year. Existence of mixed cohorts (bivoltine and uni- or multivoltine) has also been observed for E. aspersum in North Carolina (Ingram and Jenner 1976) and E. cyathigerum in Britain (Macan 1964). The latter species also was found to be univoltine at another site in Britain (Johannsson 1978), and Kormondy and Gower (1965) found E. ebrium to be univoltine in Pennsylvania as well. Pearlstone (1973) studied the feeding behavior of E. boreale in a small lake in southwestern British Columbia. Cladocerans and larval chironomids were the principal prey items, although larvae appeared opportunistic with prey choice as other prey items were consumed (e.g., mayflies, stoneflies, water mites, copepods, other damselflies, etc.). Prey choice also did not marked change among the various instars of mature instars.
Ecological information on the larvae of Coenagrion comes principally from Walker (1953), Baker and Clifford (1980) and Cannings and Cannings (1980). Larvae are widely distributed in northern latitudes, and is probably univoltine in Michigan. Walker (1953, p. 179) notes that C. resolutum, which is widely distributed in Michigan (Map 1, below), inhabits a wide variety of lentic habitats, including "almost any small permanent or subpermanent body of still water...ordinary ponds and prairie sloughs with marshy borders; in springy cat-tail marshes; in dark calla ponds; in sphagnum pools, in cool northern spruce or tamarack swamps, and in the marginal vegetation of slow weedy streams." C. interrogatum, which is found only in the northernmost part of Michigan, appears locally distributed in open fens and marshes with abundant mosses (Cannings and Cannings 1980).
Other links with information on the biology or
ecology of larval Coenagrion and
Enallagma:
Shetland,
Scotland E. cyathigerum habitat information
>>http://www.zetnet.co.uk/sigs/insects/dragon.html
Houston,
Texas Enallagma with brief habitat notes
>> http://www.io.com/~pdhulce/dragon3.html
McPeek
Enallagma
research >>
http://math.grin.edu/~brownj/374_Q3.html
Introduced
Enallagma civile to Hawaii >>
http://www.bishop.hawaii.org/bishop/ento/Megalagrion/htmlPages/Mega01.shtml
Map 1
Map 2
Map 3
Map 4
Map 5
Map 6
Map 7
Map 8
Map 9
Map 10
Map 11
Map 12
Map 13
Map 14
Map 15Caution: only mature specimens with intact lateral and medial gills can be reliabily identified to species unless an associated adult specimen is available.
1a. Second antennal segment longer than first, third segment at least 2x longer than first (Fig. 1); stout dorsal antenodal setae of median gill in complete row, if present, although may be proximally minute (Fig. 2); gills with pigment usually restricted to the tracheae, sometimes with 1-3 indistinct transverse stripes and/or an axial stripe (picture); eyes usually unpatterned (Fig. 4) - 2
Fig. 1
Fig. 2
Fig. 4
Fig. 1: Enallagma
ebrium larva (25x,
dorsal-lateral view), from Douglas Lake, Cheboygan Co., Michigan,
collected by E. J. Kormondy on 19 June 1953. UMMZODO-2000. Fig. 2:
same specimen as in Fig. 1 (25x, lateral view). Fig. 4: same specimen
as in Fig. 1 (12x, dorsal view).
1b. Second
antennal segment not longer than first, third segment < 2x longer
than first (picture); stout dorsal antenodal setae of median gill
whole or partly reduced to slender hairs or confined to the vicinity
of the nodus (picture); gills generally more extensively pigmented
(picture); eyes usually patterned with dark stripes or spots
(picture) - 14
2a.(1a). Gills with patches of closely branched and deeply
pigmented tracheae, the intervening areas with mostly unpigmented and
much less branched tracheae (picture) - 3
2b. Gills with
the tracheae uniformly and usually much less closely branched,
pigmentation of the tracheae general although often interrupted by
clear areas (picture) - 4
Back to beginning of
key
3a.(2a). Cerci of male in dorsal view bluntly angular, the
outer edge nearly straight and with an oblique ridge, in lateral view
bluntly rounded (picture); female apparently indistinguishable from
E. hageni
- E. ebrium
3b. Cerci of
male in dorsal view with an evenly curved margin and without a ridge,
in lateral view bluntly angular (picture) - E. hageni
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(2); Back to beginning of key
4a.(2b). Dorsal antenodal setae of median gill fewer than
20 (picture); cerci of male with deep dorsal concavity, easily
visible in dorsolateral view, sometimes even with dorsal margin
appearing concave in strict lateral view (picture), and in dorsal
view subacute, slightly longer than wide (picture); median gill
usually < 4.5 mm - E.
geminatum
4b. Dorsal
antenodal setae almost always 20 or more (picture); cerci of male
with concavity, if any, medial or slightly dorsomedial, not usually
visible in dorsolateral view (picture) and, if visible, cerci in
dorsal view appear more or less globular and wider than long
(picture); median gill usually > 4.5 mm - 5
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(2); Back to beginning of
key
5a.(4b). Dorsal and ventral series of stout antenodal setae
of median gill nearly equal in length and consisting of rather
closely set setae (picture) - 6
5b. Dorsal and
ventral series of stout antenodal setae of median gill nearly 2x as
ventral series, with the latter consisting of comparatively small and
widely spaced setae (picture) - 7
Back to previous couplet
(4); Back to beginning of
key
6a.(5a). Cerci in caudal view more rounded distally, in the
male shaped like clenched boxing gloves seen end-on, the distal
projection more than 0.5 as wide (from dorsomedial to ventrolateral
face) as long (picture); cerci in female with distal projection
usually higher than wide, set off from basal portion by a dorsal fold
only (picture) - E.
boreale
6b. Cerci in
caudal view less rounded distally, in the male with the distal
projection forming a distinct, transverse ridge that is less than 0.5
as wide as long (measured from above); cerci in female with the
distal projection usually not higher than wide and set off from the
basal portion by dorsal and ventral folds (picture) -
E. cyathigerum
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(5); Back to beginning of
key
7a.(5b). Males, ovipositor rudiments absent (picture) -
8
7b. Females,
ovipositor rudiments present (picture) - 11
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key
8a.(7a). Cerci very large and robust, in dorsal view >
0.38mm in length; dorsal antenodal series of setae of median gill
usually extending at least 2/3 the length of the gill -
E. anna
8b. Cerci
slenderer, in dorsal view < 0.35mm in length; antenodal setae of
gills variable - 9
Back to previous
couplet (7); Back to beginning of
key
9a.(8b). Ventral surface of cerci strongly concave in
ventrolateral view (picture); bog-ponds - E. aspersum
9b. Ventral
surface of cerci broadly convex in ventrolateral view (picture) -
10
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key
10a.(9b). Cerci in posterior view with maximum distance from
dorsomedial to ventrolateral margins greater than maximum distance
from dorsolateral to ventromedial margins (picture); cerci usually
< 0.3 mm long in dorsal view (picture) - E. carunculatum
10b. Cerci in
posterior view with maximum dorsomedial to ventrolateral margins less
than maximum dorsolateral to ventromedial distance (picture); cerci
usually > 0.3 mm in dorsal view (picture) - E. civile
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(9); Back to beginning of
key
11a.(7b). Length of cerci in dorsal view 0.29 mm or more -
12
11b. Length of
cerci in dorsal view 0.28 mm or less - 13
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key
12a.(11a). Cerci with medial margin distinctly concave in
ventrolateral view - E.
civile
12b. Cerci
with medial margin straight or barely concave in ventrolateral view -
E. anna
13a.(11b). Cerci with medial margin slightly concave in
ventrolateral view (picture); axial tracheae of gills often appearing
distinctly coiled around each other basally (picture) -
E. aspersum
13b. Cerci
with medial margin usually straight or convex, rarely very slightly
concave, in ventrolateral view (picture) axial tracheae usually not
appearing distinctly coiled around each other basally (picture) -
E. carunculatum
Back to previous couplet
(10); Back to beginning of
key
14a.(1b). Posterolateral margin of head rounded, at best
with small lobes (picture); lateral carinae of abdomen projecting
abruptly from the posterior part of each segment, but not prominent
in front, the posterior margin bearing a group of stout setae but
otherwise bare (picture); gills without patches of closely branched
and deeply pigmented tracheae (figure) - 15
14b. Posterolateral margin of head with prominent lobes
(picture); lateral carinae of abdomen evident but not projecting
abruptly from the posterior part of each segment, and (except
E. basidens) bearing only slender hairs and, if any, few stout
setae (figure); gills usually with patches of closely branched and
deeply pegment tracheae (figure) - 16
Back to beginning of
key
15a.(12a). Dorsal margin of median gill without prominent
stout setae (figure); median gill at most 3x as long as its greatest
width, in lateral view distal 2/3 greatly expanded with dorsal margin
strongly convex (figure); tracheae of gills widely spaced, usually
directly opposite and perpendicular to the axis (figure) -
E. vesperum
15b. Dorsal
margin of median gill with at least a few stout setae proximal to the
nodus (figure), number of stout setae on ventral margin of lateral
gills 45 or more, stout setae on lateral carina 30-40 (figure);
median gill at least 3x as long as its greatest width, and widening
gradually from the base with the dorsal margin not so strongly convex
(figure); tracheae more numerous than above, meeting axis at an acute
angle (figure) - E.
signatum
Back to previous couplet
(14); Back to beginning of key
16a.(12b). Median gill (lateral gills often similar) with
2-4 apical, dark, transverse bands often confluent with axis
(figure); lateral carinae of abdomen projecting rather abruptly from
posterior part of each segment, with a scattered group of stout setae
on the prominence (figure); body length not including gills usually
< 11 mm - E.
basidens
16b. Median
gill without such dark apical bands, although an irregular and
diffuse dark area may be present (figure); lateral carinae of abdomen
prominent but not projecting abruptly from the end of each segment,
and generally bearing many slender hairs but few stout setae
(figure); body length not including gills usually > 11 mm -
17
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key
17a.(14b). Gills without a distinct nodus or abrupt color
change beyond midlength, but with 4 or 5 widely spaced dark bands
formed by patches of closely brnached and darkly pigmented tracheae
(figure); gills narrow, at least 6x long as wide (figure) -
E. divagans
17b. Gills
with distinct abrupt color change (dark proximally, light distally)
about 1/3 to 1/2 the distance from the apex (figure); gills wider,
usually 4-6x long as wide (except E.
antennatum) - 18
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beginning of key
18a.(15b). Median gill with stiff dorsal setae absent or
indistinct (figure); gills usually dark brown from base to nodus
which is located 1/2 to 2/3 from base to apex (figure) -
E. traviatum
18b. Median
gill usually with distinct stiff dorsal setae proximal to nodus
(except E. antennatum) (figure); gills proximal to nodus usually less
deeply pigmented or with pigment restricted to basal and axial areas
(figure) - 19
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key
19a.(16b). Median gill without stiff, dorsal antenodal
setae, and without a definite nodus (figure); lateral gills very
narrow, 6-8x long as wide - E.
antennatum
19b. Median
gill with 8-12 stiff, dorsal antenodal setae, and gill with a
distinct nodus 1/2 the distance from base to apex (figure); lateral
gills wider, 4-5x long as wide - E.
exsulans
Back to previous couplet
(18); Back to beginning of key
Baker, R. L., and H. F. Clifford. 1982. Life cycle of an Enallagma boreale Selys population from the boreal forest of Alberta, Canada (Zygoptera: Coenagrionidae). Odonatologica 11(4):317-322.
Calvert, P. P. 1902, in Calvert, P. P. 1901-1908. Odonata. In Biologia Centrali Americana: Insecta Neuroptera. R. H. Porter & Dulau & Co.: London. Dec 1902, p. 114.
Calvert, P. P. 1919. Gundlach's work on the Odonata of Cuba: a critical study. Transactions of the American Entomological Society 45:335-396.
Cannings, R. A. 1989. Enallagma basidens Calvert, a dragonfly new to Canada, with notes on the expansion of its range in North America (Zygoptera: Coenagrionidae). Notulae Odonatologicae 3(4):53-55.
Cannings, S. G., and R. A. Cannings. 1980. The larva of Coenagrion interrogatum (Odonata: Coenagrionidae), with notes on the species in the Yukon. The Canadian Entomologist 112:437-441.
Charpentier, T. de. 1840. Libellulinae europaeae descriptae e depictae. Lipsiae, Leopold Voss. 180 pp.
Donnelly, T. W. 1989. The status of Enallagma cyathigerum (Charp.) and E. vernale Gloyd in south-central New York (Zygoptera: Coenagrionidae). Odonatologica 18:373-378.
Gloyd, L. K. 1943. Enallagma vernale, a new species of Odonata from Michigan. Occasional Papers of the Museum of Zoology, University of Michigan 479:1-8.
Hagen, H. A. 1861. Synopsis of the neuroptera of North America, with a list of the South American species. Smithsonia Miscellaneous Collections 4:1-347.
Ingham, B. R., and C. E. Jenner. 1976. Life histories of Enallagma hageni (Walsh) and E. aspersum (Hagen) (Zygoptera: Coenagrionidae). Odonatologica 5:331-345.
Johannsson, O. E. 1978. Co-existence of larval Zygoptera (Odonata) common to the Norfolk Broads (U.K.). Oecologia 32:303-321.
Kellicot, D. S. 1895. Catalogue of the Odonata of Ohio, Part 1. Journal of the Cincinnati Society of Natural History 17:195-216.
Kirby, W. F. 1890. A synonymic catalog of Neuroptera Odonata or dragonflies. Guerney and Jackson, London. 202 pp.
Kormondy, E. J., and J. L. Gower. 1965. Life history variations in an association of Odonata. Ecology 46:882-886.
Macan, T. T. 1964. The Odonata of a moorland fishpond. Int. Revue ges. Hydrobiol. 49:325-360.
Morse, A. P. 1895. New North American Odonata. Psyche 7:207-211.
O'Brien, M. F., and P. D. Pratt. 1999 (In press). Enallagma anna, a damselfly new to the Great Lakes region (Odonata: Coenagrionidae). The Great Lakes Entomologist 32(1).
Pearlstone, P. S. M. 1973. The food of damselfly larvae in Marion Lake, British Columbia. Syesis 6:33-39.
Say, T. 1839. Descriptions of new North American neuropterous insects and observations on some already described by (the late) Th. Say. Journal of the Academy of Natural Science of Philadelphia 8:9-46.
Selys-Longchamps, E. de. 1875. Notes on Odonata from Newfoundland collected in 1874 by Mr. John Milne. Entomologists Monthly Magazine 11:241-243.
Selys-Longchamps, E. de. 1876. Synopsis des agrionines, cinquième légion: Arion (suite). Le genre Agrion. Bulletin de l'Académie royale des Sciences de Belgique (2) 42:480-531.
Walker, E. M. 1953. The Odonata of Canada and Alaska, Vol. 1. University of Toronto Press: Toronto, Ontario. xi + 292 pp.
Walsh, B. D. 1862. List of the Pseudoneuroptera of Illinois contained in the cabinet of the writer, with descriptions of over forty new species, and notes on their structural affinities. Proceedings of the Entomological Society of Philadelphia 1862:361-402.
Walsh, B. D. 1863. Observations on certain N. A. neuroptera by Hagen, M. D., of Konigsberg, Prussia; translated from the original French MS., and published by permission of the author, with notes and descriptions of about twenty new N. A. species of Pseudoneuroptera. Proceedings of the Entomological Society of Philadelphia 2:167-272. [note: see also Walsh, B. D. 1862 for original description of adults, which were named in Walsh 1863. Source: Westfall and May 1996 ).
Westfall, M. J., Jr. and M. L. May. 1996. Damselflies of North America. Scientific Publishers: Gainesville, Florida. x + 650 pp.