Siphlonurus alternatus

(Say, 1824)

Northern Summer Mayfly

Siphlonurus alternatus is a minnow with a Holarctic distribution spanning North America and Europe. The is , as and emerging as between May and August. inhabit deep pools in rivers, streams, and calcareous lakes, where they feed on fine particulate detritus. Adults emerge during daylight hours, with males forming swarms at dawn and dusk.

Pronunciation

How to pronounce Siphlonurus alternatus: //sɪfləˈnjʊrəs æltərˈneɪtəs//

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Identification

As a member of , this has the characteristic traits of the including well-developed mandibular tusks in and relatively simple . Specific diagnostic features for S. alternatus are not detailed in available sources. are likely -sized with the gray drake coloration typical of the .

Habitat

Deep pools in rivers and streams; calcareous lakes; middle reaches of watercourses from foothills to lowland areas.

Distribution

Holarctic: Canada (all provinces), northeastern United States, Alaska; Northern Europe including Fennoscandia; Britain and Ireland (northern regions with highly localized distribution).

Seasonality

emerge May through August; occurs during daylight hours.

Diet

Fine particulate detritus gathered from sediment; are gathering/ .

Life Cycle

(one per year); overwinter; larval development occurs in aquatic ; emerge May–August.

Behavior

Large are capable swimmers, moving in short, darting bursts. Males swarm at dawn and dusk over light-colored substrate or floating vegetation such as water-lilies. The is likely eurythermic (tolerant of a range of temperatures).

Ecological Role

fine detritus in freshwater systems; serves as for fish and other aquatic ; provide food for terrestrial during periods.

Human Relevance

Important to fishing as a member of the gray drake group; and are significant food sources for trout and other sport fish.

Similar Taxa

  • Siphlonurus quebecensisAlso called early quill or gray drake; similar size, preferences, and angling importance; distinguished by earlier period and specific body segmentation patterns

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