Octogomphus
Selys, 1873
grappletail
Species Guides
1- Octogomphus specularis(Grappletail)
Octogomphus is a of club-tailed dragonflies ( Gomphidae) found in western North America. The single , Octogomphus specularis, is commonly called the grappletail due to the club-like widening at the end of its . The species is a restricted to lake outlet streams, where it has been observed to complete a three-year . In British Columbia, it occurs at the northern limit of its range and was rediscovered in 2020 after a 40-year absence.
Pronunciation
How to pronounce Octogomphus: /ˌɒk.təˈɡɒm.fəs/
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Identification
The grappletail can be distinguished from other club-tailed dragonflies by the pronounced club-like widening at the end of the , which gives the its . As the sole member of its , Octogomphus specularis can be identified to genus level by this characteristic abdominal club combined with its western North American distribution.
Images
Habitat
Lake outlet streams in lotic freshwater environments. These streams provide favorable conditions including warmer water temperatures (averaging 4.4–7.2°C higher than inflow streams), stable substrates, buffered discharge variation, and high-quality seston for .
Distribution
Western North America; northern range limit in British Columbia, Canada, where only seven occurrences have been documented. The was rediscovered in July 2020 at Davis Lake Provincial Park near Mission, B.C., after not being recorded in the province for 40 years.
Life Cycle
Three-year inferred from three distinct groupings of larval sizes observed in study .
Ecological Role
Larval stages function as utilizing high-quality seston in lake outlet streams. Larval abundance has been observed to decrease with distance from the lake outlet in some streams.
Human Relevance
Subject of conservation interest due to its rarity and restricted in Canada; rediscovery in British Columbia was made by citizen scientists.
More Details
Habitat Specialization
Research indicates Octogomphus specularis is a lake outlet stream , with larvae found exclusively in these environments at the northern range limit. The thermal and hydrological stability provided by lake outflow appears critical for larval development in cooler climates.
Taxonomic Note
NCBI lists the as Libellulidae, but this appears to be an error; authoritative sources including Catalogue of Life, GBIF, and primary literature consistently place Octogomphus in Gomphidae.