Somatochlora hineana

Geographic Range

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.

• Biogeographic Regions
• nearctic nearctic
  • native native

Habitat

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.

• Habitat Regions
• temperate temperate
• terrestrial terrestrial
• freshwater freshwater

• Terrestrial Biomes
• savanna or grassland savanna or grassland
• forest forest

• Aquatic Biomes
• lakes and ponds
• rivers and streams
• temporary pools

• Wetlands
• marsh marsh
• swamp swamp
• bog bog

• Other Habitat Features
• agricultural agricultural
• riparian riparian

Physical Description

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.

• Other Physical Features
• ectothermic ectothermic
• heterothermic heterothermic
• bilateral symmetry bilateral symmetry

• Sexual Dimorphism
• sexes alike

Development

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.

• Development - Life Cycle
• metamorphosis metamorphosis

Reproduction

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.

• Mating System
• polygynandrous (promiscuous) polygynandrous (promiscuous)

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.

• Key Reproductive Features
• semelparous semelparous
• seasonal breeding seasonal breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual sexual
• fertilization fertilization
  • internal internal
• oviparous oviparous
• sperm-storing sperm-storing

A Somatochlora hineana female provides yolk for her eggs and protects the eggs in her body. Adults die after reproducing; there is no parental care after birth.

• Parental Investment
• pre-hatching/birth
  • provisioning
    • female
  • protecting
    • female

Lifespan/Longevity

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.

Behavior

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.

• Key Behaviors
• flies
• glides
• natatorial natatorial
• diurnal diurnal
• nocturnal nocturnal
• motile motile
• sedentary sedentary
• territorial territorial

Home Range

Somatachlora hineana stays within 1 kilometer of its hatching site because of its exceedingly specific habitat requirements.

Communication and Perception

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.

• Communication Channels
• visual visual
• tactile tactile

• Perception Channels
• visual visual
• tactile tactile

Food Habits

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.

Adults prey on other flying insects (especially flies ) as they patrol their territories.

• Primary Diet
• carnivore carnivore
  • insectivore insectivore

• Animal Foods
• amphibians
• insects
• mollusks
• aquatic or marine worms
• aquatic crustaceans

Predation

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.

Ecosystem Roles

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.

Economic Importance for Humans: Positive

There is no known positive economic importance of Somatachlora hineana .

Economic Importance for Humans: Negative

There is no known negative economic importance of Somatachlora hineana .

Conservation Status

The IUCN lists Somatochlora hineana as near threatened, while the U.S. Fish & Wildlife Service and the State of Michigan list the species as endangered. CITES does not have a listing for S. 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.

Additional Links

Encyclopedia of Life

Contributors

Meredith Brandt (author), University of Michigan-Ann Arbor, Elizabeth Wason (editor), Animal Diversity Web Staff.

References

Abbott, J., E. Cashatt. 2007. " Somatochlora hineana " (On-line). IUCN Red List of Threatened Species. Accessed February 03, 2012 at http://www.iucnredlist.org/apps/redlist/details/20342/0 .

Balaban, J., J. Balaban. 2005. "Species Somatochlora hineana - Hine's Emerald" (On-line). BugGuide. Accessed February 03, 2012 at http://bugguide.net/node/view/11173/data .

Borror, D., C. Triplehorn, N. Johnson. 1989. An Introduction to the Study of Insects . Philidelphia: Saunders College Publishing.

Cashatt, E. 2012. " Hine's Emerald Dragonfly " (On-line). Illinois State Museum. Accessed February 03, 2012 at http://www.museum.state.il.us/research/entomology/hines/mainpage.html .

Cocchiol, M. 2007. " Somatochlora hineana " (On-line). University of Wisconsin Bioweb. Accessed February 03, 2012 at http://bioweb.uwlax.edu/bio203/s2007/cocchiol_matt/ .

Cuthrell, D. 1999. "Special animal abstract for Somatochlora hineana (Hine's emerald dragonfly)" (On-line). Michigan Natural Features Inventory. Accessed February 03, 2012 at http://www.michigandnr.com/publications/pdfs/huntingwildlifehabitat/abstracts/zoology/somatochlora_hineana.pdf .

Foster, S., D. Soluk. 2006. Protecting more than the wetland: The importance of biased sex ratios and habitat segregation for conservation of the Hine’s emerald dragonfly, Somatochlora hineana Williamson. Biological Conservation , 127/2: 158-166.

Foster, S., D. Soluk. 2004. Evaluating exuvia collection as a management tool for the federally endangered Hine's emerald dragonfly, Somatochlora hineana Williamson ( Odonata : Cordulidae ). Biological Conservation , 118: 15-20.

Gullan, P., P. Cranston. 2010. The Insects: An Outline of Entomology . Malaysia: Chapman & Hall.

Marshall, S. 2006. Insects: Their Natural History and Diversity . Buffalo, NY: Firefly Books Ltd.

Michigan Natural Features Inventory, 2013. " Somatochlora hineana : Hine's emerald dragonfly" (On-line). Rare Species Explorer (Web Application). Accessed February 03, 2012 at http://mnfi.anr.msu.edu/explorer/species.cfm?id=12124 .

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 .