Mayfly

An Identification guide to the Nymphal Mayflies
(Order EPHEMEROPTERA) of British Columbia

	GENUS IRONODES
TAXONOMIC CHARACTERS	Tarsal claws with three or more denticles near their tips, but no teeth; abdominal segments with paired dorsal tubercles; two caudal filaments well-developed (lateral filaments)
HABITAT	Attached to the undersides of rocks or debris in fast-flowing waters
HABIT	Clinging
FEEDING METHOD	Scraping or collecting-gathering
COMMENTS	Found only in western North America; uncommon
SPECIES RECORDED IN B.C. TO DATE	flavipennis

	GENUS NIXE
TAXONOMIC CHARACTERS	Maxillary palps rarely protrude from sides of head in dorsal view; head narrower than pronotum; tarsal claws with denticles, and 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 rocks or vegetation in streams and rivers
HABIT	Clinging
FEEDING METHOD	Scraping or collecting-gathering
COMMENTS	All species formerly placed in Heptagenia
SPECIES RECORDED IN B.C. TO DATE	(Akkarion) simplicioides

	GENUS RHITHROGENA
TAXONOMIC CHARACTERS	Front margin of head with a distinct notch in the midline; first and last pairs of gills enlarged and meeting beneath abdomen; three caudal filaments well-developed (lateral filaments plus middle filament)
HABITAT	Attached to stones in fast-flowing waters
HABIT	Clinging
FEEDING METHOD	Collecting-gathering or scraping
COMMENTS	Difficult to remove from surfaces to which they cling
SPECIES RECORDED IN B.C. TO DATE	hageni, morrisoni, robusta, virilis

	GENUS STENONEMA
TAXONOMIC CHARACTERS	Maxillary palps rarely protrude from sides of head in dorsal view; first and last pairs of gills not enlarged and not meeting beneath abdomen; last pair of gills reduced to slender filaments; abdominal segments with prominent posterolateral projections; three caudal filaments well-developed (lateral filaments plus middle filament)
HABITAT	Attached to rocks or vegetation in slow- to medium-flowing sandy rivers and streams
HABIT	Clinging
FEEDING METHOD	Scraping or collecting-gathering
COMMENTS	S. terminatum is the only western species within this genus
SPECIES RECORDED IN B.C. TO DATE	terminatum

Figure 12. Family Leptophlebiidae - Leptophlebia cupida nymph

FAMILY LEPTOPHLEBIIDAE

TAXONOMIC

CHARACTERS

Mandibles rarely with tusks (exception: some Paraleptophlebia spp.); maxilla with a fringed bottom edge; tarsal claws on all legs similar in structure; gills on abdominal segment 2 present; gills on abdominal segments 2-7 forked or doubled and ending in a slender process; paired dorsal tubercles on abdominal segments rarely present; head and body not distinctly flattened dorso-ventrally

DISTRIBUTION IN

NORTH AMERICA

Widespread

TOTAL NUMBER OF

GENERA IN N.A.

9

TOTAL NUMBER OF

GENERA IN B.C.

2

TOTAL NUMBER OF

SPECIES IN N.A.

72

TOTAL NUMBER OF

SPECIES IN B.C.

11

	GENUS LEPTOPHLEBIA
TAXONOMIC CHARACTERS	Tarsal claws with ventral denticles; gills on abdominal segment 1 forked, and much narrower than gills on abdominal segments 2-7, which are doubled and ending in a slender process
HABITAT	Quiet areas of lakes, ponds, or streams
HABIT	Swimming, clinging, or sprawling
FEEDING METHOD	Collecting-gathering
COMMENTS	Large surface area of gills an adaptation for low oxygen waters
SPECIES RECORDED IN B.C. TO DATE	cupida, gravastella^, nebulosa*

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

GENUS PARALEPTOPHLEBIA

TAXONOMIC
CHARACTERS

Tarsal claws with fine denticles; gills on abdominal segment 1 forked, but not much narrower than gills on abdominal segments 2-7, which are also forked; abdominal segments with rows of small spines along their posterior margins

HABITAT

Among gravel or vegetation of fast-flowing streams and rivers

HABIT

Swimming, clinging, or sprawling

FEEDING METHOD

Collecting-gathering or shredding

COMMENTS

Some species hide in cracks and crevices on the undersides of rocks

SPECIES RECORDED
IN B.C. TO DATE

bicornuta, debilis, gregalis, heteronea,
memorialis, rufivenosa, temporalis, vaciva}

	FAMILY LEPTOPHLEBIIDAE
TAXONOMIC CHARACTERS	Mandibles rarely with tusks (exception: some Paraleptophlebia spp.); maxilla with a fringed bottom edge; tarsal claws on all legs similar in structure; gills on abdominal segment 2 present; gills on abdominal segments 2-7 forked or doubled and ending in a slender process; paired dorsal tubercles on abdominal segments rarely present; head and body not distinctly flattened dorso-ventrally
DISTRIBUTION IN NORTH AMERICA	Widespread
TOTAL NUMBER OF GENERA IN N.A.	9
TOTAL NUMBER OF GENERA IN B.C.	2
TOTAL NUMBER OF SPECIES IN N.A.	72
TOTAL NUMBER OF SPECIES IN B.C.	11

	GENUS PARALEPTOPHLEBIA
TAXONOMIC CHARACTERS	Tarsal claws with fine denticles; gills on abdominal segment 1 forked, but not much narrower than gills on abdominal segments 2-7, which are also forked; abdominal segments with rows of small spines along their posterior margins
HABITAT	Among gravel or vegetation of fast-flowing streams and rivers
HABIT	Swimming, clinging, or sprawling
FEEDING METHOD	Collecting-gathering or shredding
COMMENTS	Some species hide in cracks and crevices on the undersides of rocks
SPECIES RECORDED IN B.C. TO DATE	bicornuta, debilis, gregalis, heteronea, memorialis, rufivenosa, temporalis, vaciva