Only about 30,000 extant Somatochlora hineana individuals are known to exist globally, occurring in a few clustered populations within the Nearctic region. Commonly known as Hine's emerald dragonfly, S. hineana currently can be found in Wisconsin, Michigan, Illinois, and Missouri. The majority of the global population (about 20,000 individuals) inhabits Door County, Wisconsin. Historically, the insect has been recorded in Ohio, Indiana, and Alabama; S. hineana has since disappeared from those areas. Because S. hineana has such specific habitat requirements, populations are not widespread, but rather cluster at site-specific locations. (Abbott and Cashatt, 2007; Michigan Natural Features Inventory, 2013; US Fish & Wildlife Service, 2013)
Hine's emerald dragonfly inhabits the cool, shallow, slow-moving surface water of wetlands, marshes, fens, and bogs that are fed by alkaline, mineral-rich groundwater. The water often is only a few centimeters deep, with a thin layer of marly or sandy soil and dolomitic limestone bedrock underneath.
Somatochlora hineana depends on its symbiotic relationship with a crayfish (Cambarus diogenes). During the late summer, when their shallow pools of water dry up, S. hineana nymphs stay in the burrows created by C. diogenes to avoid desiccation. (Abbott and Cashatt, 2007; Michigan Natural Features Inventory, 2013; O'Brien, 2002; Pintor and Soluk, 2006; Wisconsin Aquatic and Terrestrial Resource Inventory, 2012)
Somatochlora hineana nymphs are light to dark brown, covered with coarse hairs, and 25 mm long when mature. Like many odonates, a S. hineana nymph has a small head with small eyes; three prominent pairs of segmented legs protruding from a short thorax; and a large, rounded abdomen comprised of multiple segments. On its back are small proto-wings, but these structures are not functional. Currently, no distinctive feature can be used to positively identify S. hineana nymphs, but researchers are developing a taxonomic key to aid in their identification.
Hine's emerald dragonfly is named for the dark, metallic-green body and brilliant green eyes of the adults. Like all dragonflies, an adult S. hineana has a small head with large compound eyes; two sets of lacy wings protruding from a stout thorax; two lateral yellow stripes on its thorax; and a long, thin, ten-segmented abdomen terminating in reproductive organs. Males have distinctive terminal appendages that are used to grasp mates during copulation. Adults are 60 to 65 mm in length and have a wingspan of 90 to 95 mm. No polymorphisms are known to exist among populations. (Cashatt, 2012; Cuthrell, 1999; Wisconsin Aquatic and Terrestrial Resource Inventory, 2012)
As in all odonates, Somatochlora hineana pronymphs hatch from eggs and immediately molt to become nymphs. Somatochlora hineana individuals are aquatic nymphs for 2 to 4 years, depending on food resources, water levels, and temperature. From late June to mid-July, the nymphs crawl out of the water and molt while clinging to grasses, sedges, cattails, and other vertical surfaces. To complete metamorphosis, a nymph's exoskeleton splits at the dorsal part of the head and thorax, and the terrestrial, airborne adult emerges.
Somatochlora hineana adults are ready to feed and fly within a few hours. Adults live for 5 to 6 weeks, during which time they copulate. Females lay eggs by plunging their abdomens in shallow water and depositing clusters of eggs. Male to female ratios are roughly 1:1. (Cashatt, 2012; Cocchiol, 2007; Foster and Soluk, 2004; Gullan and Cranston, 2010; O'Brien, 2002)
Adult females typically inhabit dry areas until they are ready to mate, because males are so aggressive that they frequently injure females during copulation. Males establish and defend breeding territories against competing males by hovering and pivoting above the water.
When a female approaches the territory of a male, he grasps her head with his terminal appendages. They then fly in tandem to a site where they can land and mate, such as a leaf. The male connects the second segment of his abdomen (where his sperm is stored) to the eighth segment of the female’s abdomen (the location of her ovaries). Their two bodies form a continuous loop called a mating wheel.
A S. hineana male (like the males of many other dragonfly species) may use his penis to remove any previously deposited sperm from the female before he deposits his own sperm. Mating can last for over an hour. Somatochlora hineana is polygynandrous, with both males and females mating with multiple individuals during their 5 to 6 weeks of sexual maturity. (Cocchiol, 2007; Foster and Soluk, 2006; Gullan and Cranston, 2010)
Somatochlora hineana reproduces during its terrestrial adult stage, for 5 to 6 weeks in late June to late July. Individuals are 2 to 4 years old at sexual maturity, and they are semelparous, laying eggs only once before they die. Soon after copulation, the female lays her eggs in shallow water, and the eggs hatch as pronymphs and become nymphs either before the winter or during the following spring.
No information is available to indicate the number of eggs that S. hineana females lay, nor exactly how long it takes for their eggs to hatch. However, because fertilization is delayed and females often mate with more than one male, it is possible for the offspring of one female to have several different fathers. (Cashatt, 2012; Foster and Soluk, 2004; Foster and Soluk, 2006; US Fish & Wildlife Service, 2013)
Somatochlora hineana lives as a nymph for 2 to 4 years, depending on food availability, water levels, and temperature. After metamorphosis, S. hineana lives as an adult for 5 to 6 weeks and dies after reproducing and bearing offspring. (Cashatt, 2012)
Somatachlora hineana nymphs are most active at night, perhaps staying in their burrows during the day. They are thought to be "sit-and-wait" predators. This hunting strategy entails waiting for prey to cross their path and then attacking.
Somatachlora hineana adults are most active during the morning and afternoon. Adult individuals catch prey on the wing. Males establish a small territory, challenge other males that invade their space, and wait for females. Due to male aggression, females typically are found in dry areas, unless they are mating or laying eggs. (Cuthrell, 1999; O'Brien, 2002)
All odonates have compound eyes that can see color. Studies have indicated that the visual perception of some odonate species spans a spectrum of monocular to binocular vision, depending on how close together their eyes are positioned. These studies have not included Somatochlora hineana; however, because its eyes touch at the anterior of its head and generally are positioned forward, the vision of S. hineana likely is bifocal. Somatochlora hineana uses vision to detect potential prey, predators, competitors, and mates. In the scientific literature, there is no mention of communication among S. hineana individuals beyond physical attempts to mate or defend territory. (Borror, et al., 1989; Sherk, 1978)
Somatochlora hineana nymphs have a carnivorous diet of diverse aquatic larvae that includes mayflies, isopods, oligochaetes, flies, caddisflies, snails, amphibians, and other dragonfly larvae. They are "sit-and-wait" predators, typically waiting for prey to cross their path and then attacking.
The common predators of Somatochlora hineana nymphs include larger invertebrates, fish, turtles, and Cambarus diogenes (a crayfish). Nymphs are most susceptible to predation when they retreat to the burrows created by C. diogenes to avoid desiccation in the late summer.
Predators of S. hineana adults include birds, frogs, and spiders. For a few hours after molting, S. hineana is particularly susceptible to predation because it is relatively inactive, its exoskeleton has not yet hardened, it cannot fly, and it remains exposed on vegetation or other vertical surface. (Foster and Soluk, 2006; Pintor and Soluk, 2006)
The primary ecological role of Somatochlora hineana is as an aquatic and aerial insectivorous predator.
The dragonfly also has an unusual ecological relationship with Cambarus diogenes (a crayfish). Cambarus diogenes is a predator of S. hineana, but the dragonfly nonetheless spends a significant amount of time occupying the burrows created by C. diogenes. Somatochlora hineana occupies the crayfish burrows primarily during the late summer, when the threat of desiccation is greater than the threat of predation by C. diogenes. This relationship is mutualistic at the population level, because C. diogenes benefits from S. hineana as a food source, and S. hineana requires the burrows of C. diogenes to survive during the dry season. (Pintor and Soluk, 2006; Wisconsin Department of Natural Resources, 2011)
There is no known positive economic importance of Somatachlora hineana.
There is no known negative economic importance of Somatachlora hineana.
Somatochlora hineana is rare due to its specific and uncommon habitat requirements. The few appropriate habitats that exist are threatened directly and indirectly by industrial, commercial, residential, and recreational development, which cause habitat destruction and degradation; the effect of development on hydrology and water chemistry; agricultural non-point source pollution, which affects surface and groundwater quality; and recreational activities, such as ATV use.
Some sites that are known to be inhabited by S. hineana have been designated as nature preserves. (Abbott and Cashatt, 2007; Michigan Natural Features Inventory, 2013; US Fish & Wildlife Service, 2013)
Meredith Brandt (author), University of Michigan-Ann Arbor, Elizabeth Wason (editor), Animal Diversity Web Staff.
living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.
living in landscapes dominated by human agriculture.
having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.
a wetland area rich in accumulated plant material and with acidic soils surrounding a body of open water. Bogs have a flora dominated by sedges, heaths, and sphagnum.
an animal that mainly eats meat
animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature
union of egg and spermatozoan
forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.
mainly lives in water that is not salty.
having a body temperature that fluctuates with that of the immediate environment; having no mechanism or a poorly developed mechanism for regulating internal body temperature.
An animal that eats mainly insects or spiders.
fertilization takes place within the female's body
marshes are wetland areas often dominated by grasses and reeds.
A large change in the shape or structure of an animal that happens as the animal grows. In insects, "incomplete metamorphosis" is when young animals are similar to adults and change gradually into the adult form, and "complete metamorphosis" is when there is a profound change between larval and adult forms. Butterflies have complete metamorphosis, grasshoppers have incomplete metamorphosis.
having the capacity to move from one place to another.
specialized for swimming
the area in which the animal is naturally found, the region in which it is endemic.
active during the night
reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.
the kind of polygamy in which a female pairs with several males, each of which also pairs with several different females.
Referring to something living or located adjacent to a waterbody (usually, but not always, a river or stream).
breeding is confined to a particular season
remains in the same area
offspring are all produced in a single group (litter, clutch, etc.), after which the parent usually dies. Semelparous organisms often only live through a single season/year (or other periodic change in conditions) but may live for many seasons. In both cases reproduction occurs as a single investment of energy in offspring, with no future chance for investment in reproduction.
reproduction that includes combining the genetic contribution of two individuals, a male and a female
mature spermatozoa are stored by females following copulation. Male sperm storage also occurs, as sperm are retained in the male epididymes (in mammals) for a period that can, in some cases, extend over several weeks or more, but here we use the term to refer only to sperm storage by females.
a wetland area that may be permanently or intermittently covered in water, often dominated by woody vegetation.
uses touch to communicate
that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).
Living on the ground.
defends an area within the home range, occupied by a single animals or group of animals of the same species and held through overt defense, display, or advertisement
A terrestrial biome. Savannas are grasslands with scattered individual trees that do not form a closed canopy. Extensive savannas are found in parts of subtropical and tropical Africa and South America, and in Australia.
A grassland with scattered trees or scattered clumps of trees, a type of community intermediate between grassland and forest. See also Tropical savanna and grassland biome.
A terrestrial biome found in temperate latitudes (>23.5° N or S latitude). Vegetation is made up mostly of grasses, the height and species diversity of which depend largely on the amount of moisture available. Fire and grazing are important in the long-term maintenance of grasslands.
uses sight to communicate
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Marshall, S. 2006. Insects: Their Natural History and Diversity. Buffalo, NY: Firefly Books Ltd.
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O'Brien, M. 2002. "Hine's Emerald Dragonfly" (On-line). Michigan Odonata Survey. Accessed February 03, 2012 at http://insects.ummz.lsa.umich.edu/MICHODO/mospubs/MOSTN3.pdf.
Pintor, L., D. Soluk. 2006. Evaluating the non-consumptive, positive effects of a predator in the persistence of an endangered species. Biological Conservation, 130/4: 584–591. Accessed May 15, 2013 at http://www.des.ucdavis.edu/research/sihlab/pdfs/PintorandSoluk2006.pdf.
Sherk, T. 1978. Development of the compound eyes of dragonflies (Odonata). III. Adult compound eyes. The Journal of Experimental Zoology, 203/1: 61-68.
US Fish & Wildlife Service, 2013. "Hine's Emerald dragonfly (Somatochlora hineana)" (On-line). US Fish & Wildlife Service Species Profile. Accessed March 25, 2012 at http://ecos.fws.gov/speciesProfile/profile/speciesProfile.action?spcode=I06P.
Wisconsin Aquatic and Terrestrial Resource Inventory, 2012. "Somatochlora hineana" (On-line). "Most Wanted" Species. Accessed February 03, 2012 at http://wiatri.net/inventory/odonata/SpeciesAccounts/SpeciesDetail.cfm?TaxaID=78.
Wisconsin Department of Natural Resources, 2011. "Hine’s Emerald (Somatochlora hineana)" (On-line). Endangered Species Program Information. Accessed February 03, 2012 at http://dnr.wi.gov/topic/EndangeredResources/Animals.asp?mode=detail&SpecCode=IIODO32110.