Cordulegastridae

Spiketails are distinguished from other dragonfly families by: eyes that meet at a single point (versus broadly contiguous in darners or separated in skimmers); narrow, unpatterned wings (versus patterned wings in many skimmers); large size with black body and yellow markings; slow, deliberate flight 30–70 cm above water; and in females, the prominent spikelike ovipositor that gives the family its common name. Males differ from females in having yellow versus brown foreheads and slightly clubbed versus unclubbed abdomen with ovipositor.

Nymphs inhabit small lotic streams with clean sand and silt substrates, requiring flowing water. Adults fly above clear woodland streams and small rivers, rarely venturing far from water. Both life stages are strongly associated with clean, unpolluted running water systems.

Holarctic distribution spanning North America, South America, Europe, Asia, and Africa. Cordulegaster occurs in North Africa, Europe, Southwest Asia to China and Japan, plus North America with two species in Central America. Anotogaster is restricted to East Asia (China, Vietnam, northeastern Pakistan, Kashmir). Neallogaster occurs in Asia from the Hindu Kush through the Himalayas to China, primarily above 2000 m elevation except N. pekinensis at 500–1500 m. All eight North American species belong to Cordulegaster.

Adults active spring through early summer, with peak activity in June. Typical lifespan of adults is 3–5 years including nymphal stage.

Egg stage: females deposit eggs in sand in shallow water using prominent ovipositor, hovering vertically and making repeated dips while trapping air bubbles with body hairs to reach substrate. Nymph stage: 3–5 year lifespan primarily as nymph; nymphs are ambush predators that extend labium to capture prey. Adult stage: relatively brief compared to nymphal stage.

Adults fly slowly 30–70 cm above water when undisturbed, but can fly rapidly when disturbed. Hunt high in forest vegetation, capturing prey resting on leaves or branches (gleaning behavior). Males are remarkably territorial with behavior varying based on female oviposition activity. Females oviposit by hovering vertically and dipping abdomen repeatedly into water.

Nymphs function as ambush predators in clean stream ecosystems, consuming any prey they can capture including smaller conspecific larvae. Adults are aerial predators that glean prey from vegetation. Serve as indicators of high-quality, unpolluted lotic habitats.

Subject of conservation concern; multiple species assessed as vulnerable or threatened. Cordulegaster erronea and C. bilineata are highly vulnerable in the northeastern United States; C. obliqua is moderately vulnerable. Five species are IUCN-listed: C. bidentata, C. trinacriae, and C. heros are Near Threatened (Europe); C. helladica and C. sarracenia are Endangered due to habitat loss.

• Gomphidae (clubtails)Both families have clubbed or expanded abdomens in males, but Gomphidae have eyes widely separated versus touching at a single point in Cordulegastridae, and Gomphidae typically have patterned wings versus unpatterned in spiketails
• Aeshnidae (darners)Both are large dragonflies, but darners have eyes that broadly meet across top of head versus single-point contact in Cordulegastridae, and darners have more robust bodies with different color patterns
• Libellulidae (skimmers)Skimmers often have broad, patterned wings and eyes that do not meet at all, versus narrow unpatterned wings and contiguous eyes in Cordulegastridae; skimmers also typically perch more frequently and have different flight patterns

• dragonfly
• Odonata
• Anisoptera
• lotic
• stream
• Holarctic
• conservation concern
• ambush predator
• gleaning predator

• BugGuide
• Wikipedia
• GBIF taxonomy match
• iNaturalist taxon
• NCBI Taxonomy
• Catalogue of Life
• The Day That Dragonflies Sprang to Life | Bug Squad
• Molecular Phylogeny of the Family Cordulegastridae (Odonata) Worldwide.