Figure 10. Family Ephemeridae - Hexagenia limbata nymph

	FAMILY EPHEMERIDAE
TAXONOMIC CHARACTERS	Mandibles with large tusks projected anteriorly and visible in dorsal view; apex of hind tibia pointed; gills on abdominal segments 2-7 forked and with fringed edges
DISTRIBUTION IN NORTH AMERICA	Widespread
TOTAL NUMBER OF GENERA IN N.A.	4
TOTAL NUMBER OF GENERA IN B.C.	2
TOTAL NUMBER OF SPECIES IN N.A.	15
TOTAL NUMBER OF SPECIES IN B.C.	2

 

	GENUS EPHEMERA
TAXONOMIC CHARACTERS	Head with a bifid frontal process; mandibular tusks with hairs and spines near base; antennae with whorls of long hairs along most of their length
HABITAT	Hard, large-particle substrates of streams and lakes
HABIT	Burrowing
FEEDING METHOD	Collecting-gathering, filtering, or predation
COMMENTS	Negatively phototactic
SPECIES RECORDED IN B.C. TO DATE	simulans

 

	GENUS HEXAGENIA
TAXONOMIC CHARACTERS	Head with a rounded frontal process; mandibular tusks with hairs along their entire length; antennae with whorls of long hairs along most of their length; gills on abdominal segment 1 very small
HABITAT	Soft, fine-particle substrates of streams and lakes
HABIT	Burrowing
FEEDING METHOD	Collecting-gathering or filtering
COMMENTS	Live in U-shaped burrows; negatively phototactic and positively geotropic
SPECIES RECORDED IN B.C. TO DATE	limbata

Figure 11. Family Heptageniidae - Epeorus longimanus nymph

	FAMILY HEPTAGENIIDAE
TAXONOMIC CHARACTERS	Mandibles rarely with tusks; tarsal claws much shorter than length of tarsi; gills on abdominal segment 2 present; abdominal gills with single lamellae; paired dorsal tubercles on abdominal segments rarely present; head and body distinctly flattened dorso-ventrally
DISTRIBUTION IN NORTH AMERICA	Widespread
TOTAL NUMBER OF GENERA IN N.A.	14
TOTAL NUMBER OF GENERA IN B.C.	8
TOTAL NUMBER OF SPECIES IN N.A.	126
TOTAL NUMBER OF SPECIES IN B.C.	23

 

	GENUS CINYGMA
TAXONOMIC CHARACTERS	Maxillary palps rarely protrude from sides of head in dorsal view; labrum narrowing from base to outer edge; first and last pairs of gills not enlarged and not meeting beneath abdomen; gills on abdominal segment 1 less than half as long as gills on abdominal segment 2; last pair of gills similar to preceding pairs in shape; three caudal filaments well-developed (lateral filaments plus middle filament)
HABITAT	Attached to wood debris in fast-flowing waters of low-elevation coastal streams
HABIT	Clinging
FEEDING METHOD	Scraping or collecting-gathering
COMMENTS	Found only in western North America
SPECIES RECORDED IN B.C. TO DATE	integrum

 

	GENUS CINYGMULA
TAXONOMIC CHARACTERS	Maxillary palps protrude from sides of head in dorsal view; front margin of head with a distinct notch in the midline; first and last pairs of gills not enlarged and not meeting beneath abdomen; three caudal filaments well-developed (lateral filaments plus middle filament)
HABITAT	Attached to the undersides of stones in mountain streams
HABIT	Clinging
FEEDING METHOD	Scraping or collecting-gathering
COMMENTS	Some species live at the bases of waterfalls
SPECIES RECORDED IN B.C. TO DATE	gartrelli, kootenai, mimus, par, ramaleyi, uniformis

 

	GENUS EPEORUS
TAXONOMIC CHARACTERS	Abdominal gills flat and plate-like, some with gills forming a ventral disc for attachment to the substratum; abdominal segments without paired dorsal tubercles; two caudal filaments well-developed (lateral filaments)
HABITAT	Attached to solid objects in shallow, fast-flowing mountain streams
HABIT	Clinging
FEEDING METHOD	Collecting-gathering or scraping
COMMENTS	Two subgenera in North America: Epeorus (Iron) with pale gills and Epeorus (Ironopsis) with dark gills
SPECIES RECORDED IN B.C. TO DATE	albertae, deceptivus, dulciana, grandis, longimanus, nitidus, permangus

 

	GENUS HEPTAGENIA
TAXONOMIC CHARACTERS	Maxillary palps rarely protrude from sides of head in dorsal view; labrum the same width from base to outer edge; tarsal claws without denticles, but with one basal tooth; first and last pairs of gills not enlarged and not meeting beneath abdomen; gills on abdominal segment 1 almost as long as gills on abdominal segment 2; last pair of gills similar to preceding pairs in shape; three caudal filaments well-developed (lateral filaments plus middle filament)
HABITAT	Attached to the undersides of stones or debris in fast-flowing rivers and streams
HABIT	Clinging or swimming
FEEDING METHOD	Scraping or collecting-gathering
COMMENTS	Active, agile mayflies
SPECIES RECORDED IN B.C. TO DATE	elegantula*, solitaria

*A potentially rare and endangered species, known at present only from the South Okanagan (Scudder 1994).