Ophiogomphus howei

Geographic Range

Ophiogomphus howei , commonly known as the pygmy snaketail dragonfly, is a native species to North America. Pygmy snaketail dragonflies are found on the eastern half of North America in two distinct locations; one population which follows along the Appalachian region extending from Tennessee to New Brunswick, Ontario, and the western populations in Michigan, Minnesota, and Wisconsin. The pygmy snaketail dragonfly can be found in ten known U.S. states: Kentucky, Maine, Massachusetts, Michigan, Minnesota, New York, North Carolina, Pennsylvania, Tennessee, and Wisconsin. Ophiogomphus howei can be found in the Canadian territories of Ontario and Quebec in various locations. Much of northwestern Ontario and the western United States are without suitable habitat due to the limitations associated with this species which includes large, clear, fast-moving rivers with fine gravel substrate.

• Biogeographic Regions
• nearctic nearctic
  • native native

Habitat

Larvae of the pygmy snaketail dragonfly are found in large rivers with clear, fast-flowing, and unpolluted running waters and substrates of fine sand or pea sized gravel. The medium to large sized rivers range from 10 meters to 200 meters wide with fine substrate stream beds. Larvae do not occur in areas below dams, since the species is unable to breed at such deep depths. They are typically found at depths of 1 to 4 m.

The majority of adult life for Ophiogomphus howei species is spent hidden in forests along large rivers, which makes this species particularly difficult to study. The forest surrounding the river is needed, particularly for females, to provide habitat for foraging and mating. The specific type of forest required has not been described in publications, but is most likely a mixture of deciduous and coniferous forest.

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

• Terrestrial Biomes
• forest forest

• Aquatic Biomes
• lakes and ponds
• rivers and streams

• Other Habitat Features
• riparian riparian

Physical Description

Similar to other dragonfly species, larvae of pygmy snaketail dragonfly are flat, brown, and have divergent wing cases. Larvae can easily be identified from other members of the genus Ophiogomphus by their small size (19 to 22 mm in length), by their lack of dorsal abdominal spines, and absence of lateral hooks on the abdominal segment 7. The abdominal region also shows long cerci, which are a pair of upper appendages at the tip of segment 10 at the end of the abdomen.

The mature nymph of Ophiogomphus howei is greenish brown in color with a body covered with coarse granules to help it blend into the river bottom. Earlier instars have more of a yellowish-brown body. The body length is on average 20.5 mm, abdominal width 5.6 mm, and head width 4.7 mm.

The adults of Ophiogomphus howei are the smallest (31 to 37 mm long) members of the Ophiogomphus genus as the common name of "pygmy snaketail dragonfly" implies, and is one of the smaller dragonflies in North America with a hind-wing length of 19 to 21 mm and abdomen length of 22 to 24 mm. The adults have distinctive markings and coloration showing a bright green thorax, vivid yellow markings on the dorsal abdomen, and each wing is marked basally with a large, transparent yellow-orange patch. In the teneral stage, the thoracic markings are yellow for up to seven days.

Compared to other dragonflies of this genus the pygmy snaketail dragonfly has a greater flared abdomen. The female resembles the male except for its thicker abdomen, reduced flare, lack of secondary genitalia, presence of an ovipositor, and different number and shape of the abdominal appendages. The inner or basal portions of the hind-wings are yellow (basal half of the hind-wings in males, basal two-thirds of the hind-wings in females). The abdomen is described as having a "clubtail" since it is slightly widened at the end.

The abdomen is black in color with small, yellow spots on top that are triangular in shape and of various sizes. All abdominal segments have a yellow, triangular spot on top except for the last segment at the posterior end of the abdomen (segment 10). The eyes of this dragonfly are similar to other dragonfly species, colored green and do not meet at the top of the head. Females can be distinguished from males because they have a short, sharp horn on each side of the rear of the head.

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

• Sexual Dimorphism
• sexes colored or patterned differently
• sexes shaped differently

Development

Ophiogomphus howei exhibits hemimetabolous metamorphosis, meaning a gradual development with three distinct stages that somewhat resemble one another and lacks a pupal stage. Stages for the life cycle includes an aquatic egg, aquatic larva, and a terrestrial/aerial adult. As with most dragonflies, the pygmy snaketail spends most of its life as an aquatic larva. After the eggs hatch, the larvae burrow into gravel or sand substrates where they grow and develop. As the larvae grow, they shed or molt their skin numerous times. Most dragonfly species transform into adults in one to three years. A few studies have indicated the pygmy snaketail dragonfly may have a two-year life cycle.

At the end of their larval development, the larvae climb out of the water and attach themselves to vegetation, rocks, tree roots, woody debris, bare ground, or other structures or surfaces located along the stream banks or floating in the water as they transform into the adult stage. The larvae undergo a final molt and emerge as winged adults. Newly emerged adults, or tenerals, typically remain perched for one or two hours to dry their wings before they can fly. Adult dragonflies become sexually mature within a week or up to a month after emergence.

• Development - Life Cycle
• metamorphosis metamorphosis

Reproduction

Adult pygmy snaketail dragonflies become sexually mature usually within a week or up to a month after emergence. Males will initiate mating by grasping females with their legs and terminal appendages, then the connected pairs fly in tandem to nearby vegetation or tree canopies to mate. Breeding occurs seasonally usually during spring or early summer. Most likely pygmy snaketail dragonflies are polygynandrous, with both males and females having multiple mates.

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

After mating, females lay their eggs in riffles or rapids in streams and rivers by dipping their abdomen in the moving water. The eggs are carried by the water and are deposited in spaces in the rock, gravel, and/or sand substrate of the stream or river. Adult pygmy snaketail dragonflies are observed occasionally at breeding sites, but generally are not seen as frequently or in large numbers after the adult emergence period compared to other dragonfly species. This issue leads to a lack of current information on the number of offspring produced per breeding season and other reproductive information. Studies like the one by Gibbs et. al. (2004) indicates that the pygmy snaketail dragonfly likely requires two or more years to complete a generation. It also likely has overlapping generations and produces more than one brood or generation per year.

• Key Reproductive Features
• iteroparous iteroparous
• seasonal breeding seasonal breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual sexual
• fertilization fertilization
  • internal internal
• oviparous oviparous

Female pygmy snaketail dragonflies lay their eggs in suitable aquatic habitats for the larvae to survive in upon hatching. They also provide provisioning in the eggs. After laying her eggs, the female dragonfly then leaves the area and the eggs are carried away by the water. Males are only used in fertilization and have no role in parental investment.

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

Lifespan/Longevity

As with most dragonflies, the Ophiogomphus howei spends most of its life as an aquatic larva. The overall lifespan for O. howei is dependent on larval and nymph stages which is highly variable due to vulnerability to birds, frogs, lizards, fish, and other large dragonflies, weather, and pollution. The time required for pygmy snaketail larvae to develop into adults is currently not known. Most dragonfly species transform into adults in one to three years. In general, adult dragonflies typically live for approximately one month, and up to nine months to a year in a few species.

Behavior

Adult dragonflies need sunny warm weather to fly, with a temperature over 65°C ideal. During inclement weather such as cold and rainy days, O. howei tends to hide or lay in vegetation. Adult male dragonflies often establish territories along the edges of ponds or streams and only defend the territory against other males of their species. The larval and nymph stages of Ophiogomphus howei are mainly solitary within a river or stream, but they may travel within the river or stream over the span of the species life.

• Key Behaviors
• arboreal arboreal
• flies
• natatorial natatorial
• diurnal diurnal
• motile motile
• solitary solitary
• territorial territorial

Home Range

Since the pygmy snaketail dragonfly spends most of its expected life within a river, the home range of typical species could extend from about 1300 km or (approx 800 miles) over the span of a river. Most of the adult life of the dragonfly is spent in close vegetation or trees about (7 to 10 meters) off the ground directly next to the river, and may migrate along the length of the river or stream.

Communication and Perception

Adult pygmy snaketail dragonflies are similar to other dragonfly species who communicate visually. Mating pairs probably communicate by touch, shown when an adult male grasps females with their legs and terminal appendages and its possible that chemical communication may play a role in reproduction as well. Adult males also fight aerial duels for territories, displaying their size and speed to each other in order to communicate and ward off other dragonfly species.

• Communication Channels
• visual visual
• tactile tactile
• chemical chemical

• Perception Channels
• visual visual
• ultraviolet
• tactile tactile

Food Habits

Both adult and larval pygmy snaketail dragonflies are known as intensely ferocious carnivores and predators of most insect species. Pygmy snaketails have great speed in both the air and water, which allows them to sneak and capture prey. Larvae have been reported to feed on water mites, mayfly nymphs, and chironomids or midges as they hide behind rocks, gravel, sticks, and other debris from which they attack unsuspectingly. Adult dragonflies typically forage for flying insects, such as butterflies, moths, damselflies, mosquitoes, and flies, in sunny areas including open grassy fields, forest openings, and over streams and rivers.

• Primary Diet
• carnivore carnivore
  • insectivore insectivore

• Animal Foods
• insects
• terrestrial non-insect arthropods
• aquatic or marine worms

Predation

Predators of adult dragonflies include birds, frogs, lizards, fish, and other large dragonflies. When the dragonfly has use of its wings, it is quick and agile in flight, and hides in vegetation when it is too cold to fly. The O. howei species has adapted bright markings and a "clubtail" which most likely serves to warn off predators. Adult pygmy snaketail dragonflies also have high mortality rates due to human disturbance or environmental factors such as wind/rain after the initial hatching time when the wings of the dragonfly are wet for one or two hours. The coloration of larvae likely serves as camouflage in its aquatic habitat.

• Anti-predator Adaptations
• cryptic cryptic

Ecosystem Roles

Pygmy snaketail dragonflies are an important species in their habitats. The predators of pygmy snaketail dragonflies such as birds, frogs, lizards, fish, and other large dragonflies all consume this species and pygmy snaketails consume water mites, mayfly nymphs, chironomids or midges, butterflies, moths, damselflies, mosquitoes, and flies. Without the pygmy snaketail many species within the food web would be affected. Another important role Ophiogomphus howei provides is soil aeration. The larvae hide in between rocks and gravel and tends to move small granular sized sand grains at the bottom of streams and rivers, which serves to break up soil and allows water and air to enter the open cavity.

• Ecosystem Impact
• soil aeration soil aeration

Economic Importance for Humans: Positive

Pygmy snaketail dragonflies are economically important for humans as they help to control populations of mosquitoes. Ophiogomphus howei has also provided ample opportunities for research, including such topics as reproductive activities and timing, effects of invasive species, food preferences and forest habitat needs of adults, recolonization abilities of the species after extirpation, potential for and feasibility of reintroduction after extirpation.

• Positive Impacts
• research and education
• controls pest population

Economic Importance for Humans: Negative

There are no known adverse effects of Ophiogomphus howei on humans.

Conservation Status

Threats to the majority of the pygmy snaketail dragonfly in the northern range are moderate, but habitat threats to populations in the south appear to be more significant. These potential threats to habitat degradation can account from human activities that ruin running waters through poorly drained roads, damming, and also natural activities such as beaver damming, channelization leading to scour of microhabitats, toxic or organic pollution, and introductions of exotic species. The majority of reproduction which includes migration is effected by climate and weather and will be potentially impacted with rapid climate changes.

Additional Links

Encyclopedia of Life

BioKIDS Critter Catalog

Contributors

Brock Bermel (author), Minnesota State University, Mankato, Robert Sorensen (editor), Minnesota State University, Mankato, Angela Miner (editor), Animal Diversity Web Staff.

References

Abbott, J., N. Donnelly. 2013. " Ophiogomphus howei " (On-line). IUCN Red List of Threatened Species. Accessed March 26, 2014 at http://www.iucnredlist.org/details/summary/15366/0 .

Bradeen, B., D. Boland. 2004. Spatial and Temporal Segregation Among Six Species of Coexisting Ophiogomphus ( Odonata : Gomphidae ) in the Aroostook River, Maine. Northeastern Naturalist , 11: 295-312.

Brunelle, P. 2008. "COSEWIC Assessment and Status Report on the Pygmy Snaketail Ophiogomphus howei in Canada" (On-line). Accessed March 26, 2014 at http://www.queticofoundation.org/pdf/namakan_pygmy_snaketail.pdf .

Hamill, S. 2013. "Recovery Strategy for the Pygmy Snaketail ( Ophiogomphus howei ) in Ontario" (On-line). Ontario Recovery Strategy Series. Accessed March 26, 2014 at http://www.mnr.gov.on.ca/stdprodconsume/groups/lr/@mnr/@species/documents/document/stdprod_099158.pdf .

Hammond, G. 2014. "BioKIDS" (On-line). Anisoptera. Accessed April 23, 2014 at http://www.biokids.umich.edu/critters/Anisoptera/ .

Harris, W., D. Forman, R. Battell, M. Battell, A. Nelson, P. Brain. 2011. Odonata colour: more than meets the eye?. International Journal of Odonatology , 14: 281-289. Accessed April 23, 2014 at http://dx.doi.org/10.1080/13887890.2011.623981 .

Kennedy, J., H. White III. 1979. Description of the Nymph of Ophiogomphus howei ( Odonata : Gomphidae ). Proc. Entomol. Soc. Wash. , 81: 64-69.

Lee, Y. 2009. "Special animal abstract for Ophiogomphus howei (pygmy snaketail)" (On-line). Accessed March 26, 2014 at http://mnfi.anr.msu.edu/abstracts/zoology/Ophiogomphus_howei.pdf .

Tennessen, K. 1993. New Distribution Records for Ophiogomphus howei ( Odonata : Gomphidae ). Great Lakes Entomologist , 26: 245.

NatureServe. 2013. " Ophiogomphus howei - Bromley, 1924" (On-line). NatureServe. Accessed March 26, 2014 at http://explorer.natureserve.org/servlet/NatureServe?searchName=Ophiogomphus+howei+ .

The University of Arizona. 1997. "The University of Arizona Center for Insect Science Education Outreach" (On-line). Insect Information: Life Cycles. Accessed April 28, 2014 at http://insected.arizona.edu/insectinfo.htm .