Aquatic Insects of Michigan

by Ethan Bright, Museum of Zoology Insect Division and School of Natural Resources and Environment
University of Michigan

Ophiogomphus (Gomphidae) (Snaketails) of Michigan - Identification

Six of the approximately 17 species of Ophiogomphus known from North America have been reliably recorded in Michigan. O. rupinsulensis (Walsh, 1962), probably our most common ophiogomphid, is widely distributed throughout the state. O. carolus Needham, 1897 and O. colubrinus Selys, 1854 are widely distributed in the UP and the northern LP. O. anomalus Harvey, 1898, is known from three widely scattered records in the eastern LP and one record from Gogebic County in the western UP. New nymphal records are reported for O. anomalus (Iron Co.) and O. howei (Escanba Co.) in the UP (D. Cuthrell, Michigan Natural Features Inventory, pers. comm.). A species only recently described, O. susbehcha (Vogt and Smith 1993), may be encountered in the western part of the UP and is included in the key below (T. Vogt, pers. comm.).

Adults are quite attractive, with both sexes usually with the eyes and thorax green, the green often extending on the first couple of abdomen that is otherwise yellow or light yellowish-brown (ophis or serpentine) markings against a darker background. Wings are hyaline. Legs are short, spiny. The distal segments of the abdomen in the male is distinctly though slightly club-shaped, scarcely so in the female. Nymphs are short and stocky, with the developing wingpads characteristically divergent. (Erpetogomphus, which has not yet been recorded from Michigan, also has this character). The first two pairs of legs have strong burrowing hooks, and labium is short and broad. The abdomen is rounded, and often adorned with variously developed middorsal hooks on the posterior margin of respective abdominal segments, and lateral spines on segments 6 or 7-9.

Nymphs are common in clean rivers, streams and sometimes wave-swept shores of lakes, particularly where water quality has not been degraded by changes to flow or by siltation from channelization or agricultural activities. Frequently found in sand and/or gravel substrates, nymphs lie submerged within the substrate or underneath rocks or boulders. Sometimes more than one species is found together in one microhabitat (Vogt and Smith 1993, Dave Cuthrell pers.comm., E. Bright, pers.obs.). I (EB) have found O. rupinsulensis in similar habitat in the Pine River, Marquette Co. (26 June 1997), from which a large number of larvae had just emerged to transform on the vertical surface of a bridge support. Walker (1958) remarks that O. aspersus and O. colubrinus prefer clear, cold rapid streams with gravelly or sandy beds, whereas O. rupinsulensis appears more tolerant of warmer streams with somewhat more silting. Kennedy and White (1979), who first described the larval form of O. howei from specimens collected in Pennsylvania and Virginia, found individuals in sand and gravel substrate in clean, swiftly flowing waters. Tennessen (1993) found larvae in medium to large (10-100m width) rivers with predominately gravel and sand substrates interspersed with large rocks and boulders. He also noted the lack of disturbance due to forestry and agricultural habitats in sites that O. howei were found. Based on these Wisconsin populations, emergence in Michigan probably occurs in very late May through June. Kennedy and White (1979) also describe this species' emergence and nymphal diet: "The nymphs were observed climbing out of the river and up vertical mud banks. Emergence either occurred while clinging to the exposed mud bank or in the grassy vegetation on the top of the bank. Emergence occurred between early morning and early afternoon... Foregut contents of 5 O. howei mid-instar nymphs..revealed water mites...mayfly nymphs...and midge larvae. Two distinct size classes...were collected from the New River suggesting a 2 year life cycle."

Except for morphologically distinctive larvae of O. anomalus, O. howei and O. susbehcha (see key below), reliable species-level identification of nymphs usually works only for mature specimens and, nevertheless, is very difficult. A new work on Ophiogomphus of the Western Great Lakes (Smith and Tennessen 2016) should be consulted, and is the basis for the nymphal key below. However, identification may not be possible, especially for some species that hybrize (e.g., Tennessen 2014).

(Taxonomic References: Carle 1992, Needham et al. 2014, Smith and Tennessen 2016, Walker 1958)

Adults

1a	a. Males	2
1b	b. Females	7
2a(1a) Males	a. Epiproct curved sharply dorsally in distal half, its branches widely divergent, without a lateral tooth or protuberance on each side	3
	b. Cerci in dorsal view triangular, nearly symmetrical
	c. Either wings tinted yellow in basal half, or mesepisterna each with an oblique brown stripe above the spiracle
2b	a. Epiproct not curved sharply dorsally in distal half (may be gently curved, or sharply curved at the extreme tip), branches not widely divergent, often with a lateral tooth or protuberance on each side	4
	b. Cerci in dorsal view not triangular, distinctly asymmetrical
	c. Coloration not as above
3a(2a)	a. Transverse black bands on antefrons and postclypeus	Ophiogomphus anomalus Harvey
	b. Metepisterna each with an oblique brown stripe above the spiracle
	c. Wings hyaline basally
	d. Hindwing at least 24mm long
	e. Terga of Ab9-10 with dorsomedial yellow spots
3b	a. Antefrons and postclypeus without transverse black bands	Ophiogomphus howei Bromley
	b. Metepisterna without an oblique brown stripe above the spiracle
	c. Wings tinted with yellow in basal half
	d. Hindwing no more than 22mm long
	e. Terga of Ab9-10 without dorsomedial spots
4a(2b)	a. Epiproct with lateral protuberances vestigial, often represented by dorsal angulation at mid-length	Ophiogomphus colubrinus Selys
	b. Posterior hamules with apices shorter, not crook-like
4b	a. Epiproct with lateral protuberances prominent, directed dorsolaterally	5
	b. Posterior hamules with the apical half or more more abruptly narrowed, elongate, bent like a shepherd's crook
5a(4a)	a. Middorsal thoracic brown stripe vestigial or absent	Ophiogomphus rupinsulensis (Walsh)
	also: Tibiae with extensor surfaces predominantly yellow; lateral processes of epiproct at 3/4 its length or beyond; antehumeral and humeral brown stripes well-developed; epiproct ventromedially convace and with lateral and apical processes obtuse
5b	a. Middorsal thoracic brown stripe well-developed	6
	also: Cerci not inflated, not wider at mid-length than at the base, and no longer than epiproct; tibiae without yellow streaks along external carinae
6a(5b)	a. Epiproct with a large dorsal protuberance just anterior to the lateral projections, and with the apex of each branch turned sharply upward	Ophiogomphus susbehcha Vogt and Smith
6b	a. Epiproct without a large dorsal protuberance just anterior to the lateral projection, apex of each branch not turned sharply upward	Ophiogomphus carolus Needham
7a(1b) Females	a. Sternum of Ab10 about 4x as wide as long	8
	b. Either wings tinted yellow in basal half, or mesepisterna each with an oblique brown stripe above the spiracle
7b	a. Sternum of Ab10 about 3x as wide as long	9
	b. Coloration not as above
8a(7a)	a. Transverse black bands on antefrons and postclypeus	Ophiogomphus anomalus Harvey
	b. Mesepisterna each with an oblique brown stripe above the spiracle
	c. Wings hyaline basally, hindwing at least 24mm long
	d. Terga of Ab9-10 with dorsomedial yellow spots
	e. Subgenital plate about 1.5x as long as wide
8b	a. Antefrons and postclypeus without black transverse black bands	Ophiogomphus howei Bromley
	b. Mesepisterna without an oblique brown stripe above the spiracle
	c. Wings tinted with yellow in basal 2/3, hindwing no more than 22mm long
	d. Terga of Ab9-10 without dorsomedial spots
	e. Subgenital plate about as long as wide
9a(7b)	a. Middorsal thoracic brown stripe restricted to a thin line along crest of the middorsal carina	Ophiogomphus rupinsulensis (Walsh)
	also: Subgenital plate shorter than sternum of Ab9; tibiae with extensor surfaces predominately yellow; postoccipital horns usually well-developed, about twice as long as wide
9b	a. Middorsal thoracic brown stripe well-developed, extending laterally beyond the middorsal carina	10
10a(9b)	a. Usually with distinct postoccipital horns	Ophiogomphus colubrinus Selys
	also: Face with distinct transverse black bands; tibiae black; metapleural dark stripe well-developed
10b	a. Postoccipital horns absent or nearly vestigial	11
11a(10b)	a. Subgenital plate about 0.6x the length of Ab9 sternum, divided for about 0.5x its length, apices slightly divergent	Ophiogomphus susbehcha Vogt and Smith
11b	a. Subgenital plate about 0.8x the length of Ab9 sternum, divided for about 0.75x its length or more, apices strongly divergent	Ophiogomphus carolus Needham

Mature Nymphs

1a	a. Head width greater than maximum width of abdomen	Ophiogomphus howei Bromley
	b. Lateral spines absent or greatly reduced on Ab7
	c. Ant4 small, its width <0.3x the maximum width of Ant3
	d. Mature nymph <22mm long
	e. Dorsal hooks absent or, if vestigial, not projecting posteriorly over the intersegmental membranes
1b	a. Head width less than maximum width of abdomen	2
	b. Lateral spines developed on Ab7
	c. Ant4 usually larger, its width at least 0.3x the maximum width of Ant3
	d. Mature nymph >21mm long
	e. Dorsal hooks usually distinct, projecting posteriorly over the intersegmental membrane, though sometimes vestigial
2a(1b)	a. Ant4 nearly as wide as the adjacent portion of Ant3, forming a more or less complete cap, its lateral margin appearing continuous	3
	b. Dorsal hooks vestigial or low, usually not prominently arched (sometimes slightly arched in O. anomalus)
2b	a. Ant4 distinctly narrower than Ant3, and not completely capping that segment, the terminal end of An3 forming at least one distinct shoulder at the base of Ant4	4
	b. Dorsal hooks usually raised and slightly to greatly arched (usually appressed in O. carolus)
3a(2a)	a. Apex of Ant4 smoothly convex	Ophiogomphus anomalus Harvey
	b. Mature nymph <26mm in length
	c. Length of cerci >0.63x length of paraprocts
3b	a. Apex of Ant4 with its center raised into a papilla-shaped tip	Ophiogomphus susbehcha Vogt and Smith
	b. Mature nymph >26mm in length
	c. Length of cerci <0.64x length of paraprocts
4a(2b)	a. Width of prementum >3.03mm	Ophiogomphus colubrinus Selys [most]
	b. Middorsal punctae on Ab6 usually lenticular to oblong in shape
	c. Medial and lateral margins of cercus concave, the lateral margin usually markedly concave from base, its inner margin with a distinct basal shoulder
4b	a. Width of prementum = or <3.03mm	5
	b. Middorsal punctae on Ab6 generally oval to orbicular in shape
	c. Medial and lateral margins of cercus straight, or only the lateral margin slightly concave
5a(4b)	a. Ratio of the length of the metatibia to Ab10 width =>1.66	Ophiogomphus colubrinus Selys [some]
5b	a. Ratio of the length of the metatibia to Ab10 width =<1.66	6
6a(5a)	a. Width of Ab9 >5.07mm	Ophiogomphus rupinsulensis (Walsh) [most]
	b. Vulvar lobes of female generally convergent distally, minimum gap < the lamina width at half-length
6b	a. Width of Ab9 < or =5.07mm	7
	b. Vulvar lobes of female generally parallel or divergent distally, minimum gap > or = the lamina width at half-length
7a(6b)	a. Length of cercus < or = 1.23mm	Ophiogomphus carolus Needham [most]
	b. Ant3 widest near the middle of segment
	c. Dorsal hook of Ab7, in lateral view, appressed to very slightly arched
	d. Cuticular granules large and black
7b	a. Length of cercus >1.23mm	Ophiogomphus rupinsulensis (Walsh) [some]
	b. Ant3 widest in distal half of segment
	c. Dorsal hook of Ab7, in lateral view, moderately to heavily arched
	d. Cuticular granules variable

Bromley SW. 1924. A new Ophiogomphus (Aeschnidae: Odonata) from Massachusetts. Entomology News 35(10):343-344.
Carle FL. 1992. Ophiogomphus (Ophionurus) australis spec. nov. from the Gulf Coast of Louisiana, with larval and adult keys to American Ophiogomphus (Anisoptera: Gomphidae). Odonatologica 21(2):141-152.
Harvey FL. 1898. Contributions to the Odonata of Maine II. Entomological News 9(3):59-64.
Kennedy JH, White HB. 1979. Description of the nymph of Ophiogomphus howei (Odonata: Gomphidae). Proceedings of the Entomological Society of Washington 81(1):64-69.
Needham JG. 1897. Preliminary studies of N. American Gomphinae. The Canadian Entomologist 29(7):164-168, (8):181-186.
Needham JG, Westfall MJ, May ML. 2010. Dragonflies of North America, Third Edition. Scientific Publishers, Gainesville, Florida, USA. xiv + 657 p.
Paulson D. 2011. Dragonflies and damselflies of the East. Princeton Field Guides. Princeton University Press, Pinceton, New Jersey, USA. 538 p.
Smith WA, Tennessen KJ. 2016. Description of the nymph of Ophiogomphus smithi (Odonata: Gomphidae), with a key to the species of Ophiogomphus in the Western Great Lakes region. The Great Lakes Entomologist 49(1-2):78-97.
Tennessen KJ. 1993. New distribution records for Ophiogomphus howei (Odonata: Gomphidae). The Great Lakes Entomologist 26(3)245-249.
Tennessen KJ. 2014. A hybrid male in the Genus Ophiogomphus (Odonata: Gomphidae). Insecta Mundi 0637:1-6.
Vogt TE, Smith WA. 1993. Ophiogomphus susbehcha spec. nov. from North Central United States (Anisoptera: Gomphidae). Odonatologica 21(2):141-152.
Walker EM. 1958. The Odonata of Canada and Alaska, Volume 2. University of Toronto Press: Toronto, Ontario, Canada. xii + 318.
Walsh BD. 1862. List of the Pseudoneuroptera of Illinois contained in the cabinet of the writer, with descriptions of over forty new species, with notes on their structural affinities. Proceedings of the Academy of Natural Sciences Philadelphia 14:361-402.

Page created: July 17, 1998 - Last updated: February 20, 2017