Aquatic Insects of Michigan

by Ethan Bright, Museum of Zoology Insect Division and School of Natural Resources and Environment
University of Michigan

Simuliidae (Black Flies) of Michigan - Identification

Adults
(adapted from Adler et al. 2004)

1a	a. Radial sector with fork longer than its stem	Prosimulii, 2
	b. Costa with hairlike setae only
	c. Katepisternum sulcus wide, shallow
	d. Basitarsus of hind leg without calcipala and pedisulcus
1b	a. Radial sector unforked, or with fork shorter than its stem	Simuliini, 6
	b. Costa with spiniform setae interspersed among hairlike setae (although absent from costa in some Greniera)
	c. Katepisternum sulcus narrow, deep
	d. Basitarsus of hind leg with or without calcipala and pedisulcus
2a(1a)	a. Antenna with 7 flagellomeres	Twinnia tibblesi Stone & Jamnback
	b. Eye with a shiny, dark, raised tubercle (stemmatic bulla) just behind posterior margin
	c. Claws of female toothless
	also: Vestiture of head and body consisting of long, dense recumbent hairs; wing pale brown, hyaline, not especially wrinkled; clypeus sparsely covered with hair; male gonostylus with 1, rarely 2, large apical spinules (clearly visible under dissecting microscope); female cercus and anal lobe separated by membrane
2b	a. Antenna with > 8 flagellomeres, or if with 7, then character b and c	3
	b. Posterior margin of eye without raised tubercle (stemmatic bulla)
	c. Claws of female toothless or each with variously sized basal or subbasal tooth or lobe
3a(2b)	a. Male	4
3b	a. Female	5
4a(3a)	a. Ventral plate in lateral view flattened, with lip absent, short or slender	Helodon Enderlein
4b	a. Ventral plate in lateral view not markedly flattened, typically with prominent lip	Prosimulium Roubard
5a(3b)	a. Claws (slide mounted if necessary) each with variously sized but distinct basal or subbasal tooth or lobe	Helodon Enderlein
	b. Hypogynial valve short, broadly rounded or truncated posteriorly, not extended to anal lobe (giving abdomen a somewhat rounded appearance posteriorly)
	c. Spermatheca with small or no unpigmented area at junction with spermathecal duct, or entirely unpigmented
5b	a. Claws toothless, or each with only minute subbasal tooth	Prosimulium Roubard
	b. Hypogynial valve long, produced posteriorly, extended beyond the anal lobe (giving abdomen a pointed appearance posteriorly)
	c. Spermatheca with large unpigmented area at junction with spermathecal duct
6a(1b)	a. Basitarsus of hind leg with pedisulcus deep and conspicuous	Simulium [in part]
	b. Calcipala well-developed (small in subgenus Psilozia)
	c. Wing without basal medial cell d. Radius of wing with or without setae dorsobasally
6b	a. Basitarsus of hind leg with pedisulcus absent or represented only by a shallow depression or wrinkles	7
	b. Calcipala poorly to well-developed
	c. Wing with basal medial cell, although often minute d. Radius of wing with setae dorsobasally
7a(6b)	a. Costa with only pale setae, some of which may be short and stiff but neither dark nor fully spiniform	Greniera Doby & David [in part]
7b	a. Cost with stout, black spiniform setae interspersed among longer, paler hairlike setae (the former more prevalent near apex of costa)	8
8a(7b)	a. Male	9
8b	a. Female	13
9a(8a)	a. R1 dorsally with hairlike setae and scattered, black spiniform setae on distal two-thirds or more	10
	b. Spiniform setae near apex more numerous than, and as stout as, those on costa
9b	a. R1 dorsally with hairlike setae only, or if spiniform setae present, these are confined to apical half or less and not as stout as those on costa	12
10a(9a)	a. Gonostylus with 2-3 apical spinules	Ectemnia Enderlein
	b. Ventral plate in ventral view wide, about 2.5-3.0 x broad as long
10b	a. Gonostylus with 1 apical spinule	11
	b. Ventral plate in ventral view narrower, < 2.0 x broad as long
11a(10b)	a. Basitarsus of hind leg with pedisulcus represented by, at most, shallow wrinkles	Metacnephia saskatchewana (Shewell & Fredeen)
11b	a. Basitarsus of hind leg with pedisulcus represented by shallow depression	Simulium Latrielle [in part]
12a(9b)	a. Basitarsus of hind leg with calcipala typically prominent, lamellate, rounded apically, in medial view overlapping the base of the tarsomere 2	Stegopterna Enderlein
	b. If calcipala small, then hind tibial spurs with hyaline apices and longer than width of tibia at point of attachment
12b	a. Basitarsus of hind leg with calcipala either small and rather pointed apically, or apparently absent, in medial view typically not overlapping base of tarsomere 2	Cnephia Enderlein
	b. Hind tibial spurs uniformly dark, subequal in length to, or shorter than, width of tibia also: Parameral spines present
13a(8b)	a. R1 dorsally with hairlike setae and scattered, black spiniform setae on distal half	14
	b. Wing hyaline, with basal medial cell minute or absent
13b	a. R1 dorsally with hairlike setae only, or if with few spiniform setae then character	15
	b. Wing rather smoky, and with distinct basal medial cell
14a(13a)	a. Basitarsus of hind leg with pedisulcus represented by, at most, shallow wrinkles	Metacnephia saskatchewana (Shewell & Fredeen)
14b	a. Basitarsus of hind leg with pedisulcus represented by shallow depression	Simulium Latrielle [in part]
15a(13b)	a. Claws toothless	Stegopterna Enderlein
	b. Basitarsus of hind leg with calcipala typically prominent, lamellate, rounded apically, in medial view overlapping base of tarsomere 2; if calcipala rather small, then hind tibial spurs with hyaline apices and longer than width of tibia at point of attachment
15b	a. Claws each with small subbasal tooth or large basal thumblike lobe	16
	b. Basitarsus of hind leg with calcipala either small and rather pointed apically, in medial view not overlapping base of tarsomere 2, or apparently absent; if calcipala slightly lamellate, then hind tibial spurs uniformly dark, subequal in length to, or shorter than, width of tibia
16a(15b)	a. Spermatheca elongate, with large unpigmented area at junction with spermathecal duct	Ectemnia Enderlein
	b. Anteroventral margin of cibarium with 1-11 setae
16b	a. Spermatheca spherical, wrinkled and large, with small or no unpigmented area at junction with spermathecal duct	Cnephia Enderlein
	b. Anteroventral margin of cibarium without setae

Pupa
(adapted from Adler & Currie 2008)

1a	a. Coccon rudimentary or shapeless and saclike	2
1b	a. Coon shaped like a slipper, boot or shoe, with definitely formed, rigid walls	6
2a(1a)	a. Ab4-5 with large pleurite in lateral striate membrane	3
2b	a. Ab4-5 without large pleurites, or with at most, minute pleurites in lateral striate membrane	4
3a(2a)	a. Ab6-9 each with a transverse row of spine combs along the anterior margin	Helodon Enderlein, Prosimulium Roubard
	b. Ab3-4 terga each with 4 pairs of recurved hooks
3b	a. Ab6-9 terga without spine combs	Twinnia tibblesi Stone & Jamnback
	b. Ab3-4 terga each with 3 pairs of recurved hooks
4a(2b)	a. Ab8-9 laterally with hook-shaped setae	Cnephia Enderlein
	b. Gill of 17-50 filaments
4b	a. Ab8-9 laterally either with straight or slightly curved setae, or without setae	5
	b. Gill of 6-30 filaments
5a(4b)	a. Gill of 10 or 12 filaments arising from base on 2 or 3 slender trunks	Stegopterna Enderlein
5b	a. Gill of 15-20 slender, delicate filaments typically projected forward	Greniera Doby & David
6a(1b)	a. Gill of 8 or 10 stout filaments arising close to base and converging anteriorly toward a common point	Ectemnia Enderlein
	b. Cocoon attached to silk stalk
6b	a. Gill with various numbers of filaments, but if 8 or 10, then filaments not inflated nor converging anteriorly toward a common poin	6
	b. Cocoon not attached to silk stalk
7a(6b)	a. Pleural region of Ab8-9 with numerous anchor- or grapnel-shaped seta	Metacnephia saskatchewana (Shewell & Fredeen)
	b. Cocoon typically boot-shaped, loosely or tightly woven, but without definitely formed anterior aperatures or loops
7b	a. Pleural region of Ab8-9 at most with unbranched setae	Simulium Latrielle
	b. Cocoon variously shaped, but if boot-shaped, then with definitely formed aperatures, loops, or perforations anteriorly

Larva
(adapted from Adler & Currie 2008)

1a	a. Labral fans absent	Twinnia tibblesi Stone & Jamnback
	b. Head tapered anteriorly
	also: Frontoclypeal apotome without posterolateral head spots; labrum without bulges on lateral margins
1b	a. Labrans fans present (often closed, but with stalks obvious)	2
	b. Head with sides nearly parallel
2a(1b)	a. Antenna with proximal and medial articles transparent, colorless, contrasting with dark brown distal article	3
	b. Hypostoma with intermediate teeth between primary teeth
	c. Paralateral teeth absent
2b	a. Antenna with proximal and medial articles lightly to darkly pigmented, or if colorless, then postgenal cleft extended anteriorly to, or beyond, hypostomal groove	4
	b. Hypostoma without intermediate teeth between primary teeth
	c. Paralateral teeth present
3a(2a)	a. Prothoracic proleg with lateral sclerite a narrow bar parallel to base of hooks, extended at most 1/3 x the distance to base of the apical article (requires dissection if apical article is withdrawn)	Helodon Enderlein
3b	a. Prothoracic proleg with lateral sclerite extended 1/2 x or more the distance to base of the apical article (requires dissection if apical article is withdrawn)	Prosimulium Roubard
4a(2b)	a. Hypostoma with lateral and sublateral teeth not clustered on prominent, common lobes (median and lateral teeth can be extended beyond the sublateral teeth, but not on prominent lobes)	5
	b. In doubtful specimens (i.e., Simulium subgenus Hellichiella, in part), heavily sclerotized anterior portion of hypostoma occupying at most 1/6 total length of the hypostoma
4b	a. Hypostoma with 1 or more sublateral teeth and 1 or more paralateral teeth clustered on prominent, common lobes, giving the hypostoma a trilobed appearance (consisting of a median tooth and 2 lateral lobes)	8
	b. Heavily sclerotized anterior portion of the hypostoma occupying 1/3 or more the total length of the hypostoma
5a(4a)	a. Hypostoma with apex of median tooth extending anteriorly to, or beyond, apices of the lateral teeth	Simulium Latrielle
	b. Sublateral teeth variously but distinctly posterior to median and lateral teeth
5b	b. Sublateral teeth with apices extended to various levels	6
	a. Hypostoma with apex of median tooth posterior to apices of the lateral teeth, or all teeth uniformly small
6a(5b)	a. Postgenal cleft extended anteriorly to, or slightly beyond, hypostomal groove	Metacnephia saskatchewana (Shewell & Fredeen)
	b. Antenna with transparent, colorless proximal and medial articles contrasting with dark brown distal article
6b	a. Postgenal cleft extended anteriorly 1/2 or less the distance to the hypostomal groove, broadly rounded or pointed anteriorly	7
	b. Antenna with proximal and medial articles variously pigmented, but not entirely transparent
7a(6b)	a. Abdomen with abrupt lateral and ventral expansion at Ab5, and with a pair of ventral tubercles on Ab9	Ectemnia Enderlein
	b. Hypostoma with the anterior margin distinctly concave
7b	a. Abdomen without abrupt lateral and ventral expansion at Ab5, and without a pair of ventral tubercles on Ab9	Cnephia Enderlein
	b. Hypostoma with the anterior margin in form of 3 short, convex lobes
8a(4b)	a. Ab9 with pair of prominent ventral tubercles	Greniera Doby & David
8b	a. Ab9 without a pair of ventral tubercles, but with at most 1 transverse, midventral bulge	Stegopterna Enderlein
	also: Antenna longer than stalk of labral fan by 1/2 length of the distal article; hypostoma with outer margin of lateral cluster of teeth typically sloped inwardly

Cnephia Enderlein

Two species of Cnephia are reported from Michigan, C. dacotensis and C. ornithophilia. It is currently not possible to differentiate the two species of Cnephia found in Michigan based solely on morphological characters, as cytological characters of polytene chromosomes are required (see Adler et al. 2004). Associated adult material is required, for which the key below is adapted from Adler et al. 2004.

Adults

1a	a. Males	2
1b	a. Females	3
2a(1a)	a. Gonostylus in dry specimens shiny on apical 1/3 or more	Cnephia dacotensis (Dyar & Shannon)
	b. Ventral plate in ventral view broad, about as long as wide also: Gonostylus in inner lateral view not markedly curved near apex
2b	a. Gonostylus in dry specimens dull throughout	Cnephia ornithophilia Davies, Peterson & Wood
	b. Ventral plate in ventral view truncated pasoteriorly also: Ab3-7 sterna with relatively few hairs, those on Ab3-4 moderately long and extended laterally beyond margins of abdomen, but those on remaining segments decreasing in length and mostly short on Ab6-7
3a(1b)	a. Ab9 terga with posterior margin produced as a narrow snoutlike projection	Cnephia dacotensis (Dyar & Shannon)
	b. Claws toothless, or each with minute subbasal tooth
3b	a. Ab9 terga with posterior margin evenly rounded	Cnephia ornithophilia Davies, Peterson & Wood
	b. Claws each with basal thumblike lobe
	also: Ab8-9 terga shiny, contrasting with dull preceding segments; spermatheca with a small but distinct unpigmented area at junction with spermathecal duct

Ectemnia Enderlein

Two species of Ectemnia are reported from Michigan, E. taeniatifron and E. invenusta. Descriptions, biology and cytology are described in detail in Moulton and Adler (1997) and Adler et al. (2004). Stone (1964) also gives a general description: "This rather large, grayish-brown species is also recognizable by three slender pale lines on the scutum and the pale hairs of the stem. The pupa is found in a pocket-shaped cocoon with a ragged anterior margin, attached to rocks by a stalk composed of debris enclosed in a dense sheath of silklike fibers. Larvae and pupae of E. invenusta are found among moss on rocks in swiftly flowing water, unbroken water of permanent streams at a depth of 1 to 4 ft. Adults emerge in early spring, and there is apparently only one generation a year, with overwintering in the larval stage." The keys for Ectemnia below are adapted from Adler et al. 2004.

Adults

1a	Females	2
1b	Males	3
2a(1a)	a. Series of seven or more setae along the anteroventral margin of the cibarium	Ectemnia invenusta (Walker)
2b	a. Not as above	Ectemnia taeniatifrons (Enderlein)
3a(1b)	a.Ventral plate in ventral view tapered posteriorly	Ectemnia invenusta (Walker)
	b. Ventral plate in lateral view tapered apically
3b	a. Ventral plate in ventral view subrectangular, with lateral margins extended to or beyond longitudinal plane of arms	Ectemnia taeniatifrons (Enderlein)
	b. Ventral plate in lateral view not tapered apically or, if tapered, dorsal margin sloped apically
	also: Ventral plate in lateral view with the dorsal and ventral margins subparallelb; mesepimeral tuft usually covering upper half of mesepimeron

Pupae

1a	a. Gill of 8 filaments also: coccoon without an anteriodorsal projection	Ectemnia invenusta (Walker)
	b. Gill with the third pair of filaments from dorsum nearly sessile
1b	a. Gill of 9-12 filaments	Ectemnia taeniatifrons (Enderlein)
	b. Gill with fourth pair of filaments nearly sessile

Larvae

1a	a. Slide mounted hypostoma with the anterior margin slightly concave	Ectemnia invenusta (Walker)
	b. Gill histoblast of 8 filaments
1b	a. Slide mounted hypostoma with the anterior margin moderately concave	Ectemnia taeniatifrons (Enderlein)
	b. Gill histoblast of 10 filaments

Greniera Doby & David

Adults

1a	a. Males	2
1b	a. Females	4
2a(1a)	a. Antenna with 8 flagellomeres	Greniera denaria Davies, Peterson, & Wood
	b. Gonostylus tapered to pointed apex, with 1 apical spinule
2b	a. Antenna with 9 flagellomeres	3
	b. Gonostylus only slightly tapered to rounded apex, with 2 apical spinules
3a(2b)	a. Scutum with whitish hair	Greniera abdita (Peterson)
3b	a. Scutum with brownish hair	Greniera abditoides Wood
4a(2b)	a. Antenna with 8 flagellomeres	Greniera denaria Davies, Peterson, & Wood
4b	a. Antenna with 9 flagellomeres	5
5a(4b)	a. Clypeus large, somewhat bulbous, about half the length of the head	Greniera abdita (Peterson)
5b	a. Clypeus small, not bulbous, less than half the length of the head	Greniera abditoides Wood

Pupae

1a	a. Abdomen with spine combs, typically minute and pale, on at least tergites 7 and 8	Greniera denaria Davies, Peterson, & Wood
1b	a. Abdomen without spine combs on any tergites	2
2a(1b)	a. Gill of 17-23 filaments	Greniera abdita (Peterson)
	b. Ventralmost gill trunk giving rise to 4-7 filaments
2b	a. Gill of 21-26 filaments	Greniera abditoides Wood
	b. Ventralmost gill trunk giving rise to 9-10 filaments

 

Larvae

1a	a. Antenna with proximal article as long as, or shorter, than the median article	Greniera denaria Davies, Peterson, & Wood
	b. Distal article entirely dark
	also: Antenna (slide mounted) with the medial article bearing minute spicules; postgenal cleft extended 1/3-1/2 distance to the hypostomal groove
1b	a. Antenna with proximal article 2x or more longer than the median article	2
	b. Distal article (slide mounted) with dark irregular or spiral bands or mottling
	also: Hypostoma with lateral teeth broadly pointed, broader than and extended anteriorly beyond, the median tooth
2a(1b)	a. Antenna with proximal article 2-3x as long as the medial article	Greniera abdita (Peterson)
	b. Head spots pale, indistinct
	c. Gill histoblast of 15-23 filaments
2b	a. Antenna with proximal article 3x as long as the medial article	Greniera abditoides Wood
	b. Head spots dark, distinct
	c. Gill histoblast of 21-26 filaments

Helodon and Prosimulium

The keys below are adapted from from Adler et al. 2004.

Helodon - Adults

1a	a. Males	2
1b	a. Females	4
2a(1a)	a. Antenna with 9 flagellomeres	H. vernalis
2b	a. Antenna with 7 or 8 flagellomeres	3
3a(2b)	a. Ventral plate in ventral view (excluding the anterior process) wider than long	H. decemarticulatus
	b. Median sclerite blunt apically
3b	a. Ventral plate in ventral view (excluding the anterior process) longer than widey	H. gibsoni
	b. Median sclerite pointed apically
4a(1b)	a. Antenna with 9 flagellomeres	H. vernalis
	b. Stem vein with dark hair
4b	a. Antenna with 7-8 flagellomeres	5
	b. Stem vein with pale hair
5a(4b)	a. Antenna with 8 flagellomeres	H. decemarticulatus
	b. Antenae and legs yellowish orange, contrasting with brown body
	c. Lacinia (slide mounted) with retrorse teeth
5b	a. Antenna with 7 flagellomeres	H. gibsoni
	b. Antennae and legs brown, concolorous with body
	c. Lacinia (slide mounted) with fine hair only

Prosimulium - Adults

Note: adults of P. canutum are currently unknown

1a	a. Females	2
1b	a. Males	5
2a(1a)	a. Antenna with the first flagellomere typically longer than the pedicel	P. albionense, P. multidentatum [P. canutum probably keys here: Adler et al. 2004]
	b. Spermatheca wider than long (requires clearing and slide mounting)
2b	a. Antenna with the first flagellomere subequal in length than the pedicel	3
	b. Spermatheca as long, or longer than, wide (requires clearing and slide mounting)
3a(2b)	a. Palpomere III in lateral view with the sensory vesicle opening to the outside directly, or through, the short neck by means of a wide mouth	P. fontanum
3b	a. Palpomere III in lateral view with the sensory vesicle opening to the outside directly, or through, the short neck by means of a wide mouth	4
4a(3b)	a. Hypogynial valve with sclerotization of inner margin expanded anterolaterally	P. approximatum, P. arvum (in part), P. fuscum
4b	a. Hypogynial valve with sclerotization of inner margin expanded anterolaterally	P. arvum (in part), P. mixtum
5a(1b)	a. Antenna with first flagellomere longer in length to the pedicel	6
	b. Ventral plate in ventral view evenly tapered and broadly rounded posteriorly
5b	a. Antenna with first flagellomere subequal in length to the pedicel	7
	b. Ventral plate in ventral view abruptly tapered or subrectangular, not evenly tapered or broadly rounded posteriorly
6a(5a)	a. Gonostylus with 2 or 3 (rarely 4) apical spinules	P. albionense
6b	a. Gonostylus with 4-7 apical spinules	P. multidentatum [P. canutum probably keys here: Adler et al. 2004]
7a(5b)	a. Ventral plate in ventral view with body abruptly narrowed, keel-like	P. approximatum
7b	a. Ventral plate in ventral view somewhat square or rectangular, not abruptly narrowed	8
	also: Ventral plate in lateral view with its lip large, broadly rounded, slightly or not at all upturned
8a(7b)	a. Palpomere 3 in lateral view with sensory vesicle opening to the outside directly, or through, a short neck and wide mouth (requires slide mounting)	P. fontanum
8b	a. Palpomere 3 in lateral view with sensory vesicle opening to the outside through a distinct neck that is not expanded into a wide mouth	9
9a(8b)	a. Basal fring typically brownish	P. arvum (in part), P. mixtum
9b	a. Basal fring typically grayish, silvery, or pale golden	P. fuscum

Pupae

1a	a. Gill of 9 filaments	Helodon decemarticulatus
1b	a. Gill of 13 or more filaments	2
2a(1b)	a. Gill of 13-16 filaments	3
2b	a. Gill of 20 or more filaments	5
3a(2a)	a. Gill of 13 or 14 (rarely 15 or 16) filaments	Helodon gibsoni
	also: Gill with basal trunks not swollen; in lateral view trunks rather evenly spaced
3b	a. Gill of 16 (rarely 13 or 14) filaments	4
	also: Gill filaments in lateral view in 1 or 3 groups ; gills longer than 1/2 length of pupal body
4a(3b)	a. Gill with the dorsal trunk bearing 2 main branches, the outer branch with 3 filaments, the inner branch that divides into an innermost branch with 2 filaments and a mesal branch with 3 filaments	Helodon vernalis
4b	a. Gill with the dorsal trunk bearing 3 main branches, or if appearing as 2, then arranged with an inner branch with 3 filaments, and an outer branch dividing into an inner branch with 2 filaments and another branch with 3 filaments	Prosimulium approximatum, P. arvum, P. fontanum, P. fuscum, P. mixtum
5a(2b)	a. Gill of 24-75 filaments	Prosimulium albionense
5b	a. Gill of 20-28 filaments	Prosimulium canutum, P. multidentatum

Larvae

1a	a. Prothoracic proleg with the lateral sclerite a narrow bar lying parallel to the base of the hooks, extended at most 1/3 the distance to the base of the apical article [note: Adler et al. 2004 advise this might require dissection if the apical article is withdrawn]	Helodon Enderlein, 2
1b	a. Prothoracic proleg with lateral sclerite better developed than above, extending half or more the distance to the base of the apical article [see dissection note above]	Prosimulium Roubard, 4
2a(1a)	a. Anal sclerite X shaped, with well-developed anterodorsal and posteroventral arms	Helodon vernalis
	b. Postgenal cleft in the shape of an inverted U or V, extended about 1/4 or less the distance to the hypostomal groove
2b	a. Anal sclerite subrectangular, with anterodorsal and posteroventral arms weakly, if at all, developed	3
	b. Postgenal cleft in the shape of an inverted U or square notch, extended more than 1/4 the distance to the hypostomal groove
3a(2b)	a. Hypostoma with the median tooth extended nearly to the same level as the sublateral teeth, which are posterior to the lateral teeth	Helodon decemarticulatus
	b. Gill histoblast of 9 filaments
3b	a. Hypostoma with the median tooth posterior to the sublateral teeth, which are extended anteriorly to the same level as the lateral teeth	Helodon gibsoni
	b. Gill histoblast of 14 filaments
4a(1b)	a. Antenna shorter than the stalk of the labral fan	5
	b. Abdomen gradually posteriorly
	c. Gill histoblast of more than 20 filaments
4b	a. Antenna as long or longer than the stalk of the labral fan	7
	b. Abdomen rather abruptly expanded at Ab5
	c. Gill histoblast of 16 or fewer filaments
5a(4a)	a. Body grayish, banded (i.e., with conspicuous intersegmental lines	Prosimulium multidentatum
5b	a. Body pale grayish to dark brown, but not banded (i.e., with thin intersegmental lines)	6
6a(5b)	a. Body grayish	Prosimulium canutum
	b. Head yellowish
6b	a. Body brownish	Prosimulium albionense
	b. Head yellowish brown to dark brown
7a(4b)	a. Frontoclypeal apotome yellowish white, contrasting strongly with dark brown head spots	Prosimulium arvum
7b	a. Frontoclypeal apotome yellowish brown to brown, variously contrasting with brown head spots	8
	also: Gill histoblast of 3 primary trunks with 14-16 filaments
8a(7b)	a. Frontoclypeal apotome with half of first posterolateral head spot brown	Prosimulium fuscum
	b. Body typically grayish, slightly banded
8b	a. Frontoclypeal apotome with first posterolateral head spot typically yellowish or apparently absent	9
	b. Body brownish, not banded
	also: Gill histoblast with filaments arising from 3 unswollen to slightly swollen trunks
9a(8b)	a. Hypostoma (slide mounted) with each of 2 outer sublateral teeth on each side asymmetrical, extended anteriorly to the same level as the lateral teeth, giving the anterior margin a straight or convex appearance	Prosimulium approximatum
9b	a. Hypostoma (slide mounted) with each of 2 outer sublateral teeth on each side symmetrical, slightly to distinctly posterior to the lateral teeth, giving the anterior margin a concave appearance	10
10a(9b)	a. Hypostoma (slide mounted) with the lateral teeth extended anteriorly well beyond the sublateral teeth	Prosimulium fontanum
10b	a. Hypostoma (slide mounted) with the lateral teeth extended anteriorly slightly beyond the sublateral teeth	Prosimulium mixtum

Stegopterna Enderlein

Adults
(adapted from Adler et al. 2004)

Note: the male of Stegopterna mutata, which is parthenogenetic, does not exist

1a	a. Males	2
1b	a. Females	3
2a(1a)	a. Calipala about > 0.5 x as wide as apex of the basitarsus	Stegopterna diplomutata Currie & Hunter
2b	a. Calipala about < 0.5 x as wide as apex of the basitarsus	Stegopterna emergens (Stone)
	also: Paramere with apical margin smooth or finely toothed; aedeagal membrane with fine spines and hair
3a(1b)	a. Calipala about > 0.5 x as wide as apex of the basitarsus	Stegopterna diplomutata Currie & Hunter, Stegopterna mutata (Malloch)
	b. Spermatheca with small unpigmented area at junction with spermathecal duct
	c. Lacinia (slide mounted) with retorse teeth
	d. Mandible (slide mounted) with serrations
3b	a. Calipala about < 0.5 x as wide as apex of the basitarsus	Stegopterna emergens (Stone)
	b. Spermatheca with pigmentation extended slightly onto the spermathecal duct
	c. Lacinia (slide mounted) without retorse teeth
	d. Mandible (slide mounted) without serrations
	also: Spermatheca smooth, without raised rounded areas; anal lobe in ventral view narrow, sclerotized anteriorly

Pupae

1a	a. Gill typically of 3 main groups of filaments, with branching pattern 4+3+5	Stegopterna emergens (Stone)
1b	a. Gill typically of 2 main groups of filaments, with branching pattern 7+5	Stegopterna diplomutata Currie & Hunter, Stegopterna mutata (Malloch)

Larvae

1a	a. Postgenal cleft typically extended > 0.25 x the distance to the hypostomal groove	Stegopterna emergens (Stone)
1b	a. Postgenal cleft extended < 0.25 x the distance to the hypostomal groove	2
note: S. diplomutata and S. mutata can only be distinguished by staining gonads for polytene chromosomes
2a(1b)	a. Chromosomes triploid, female larvae only (males do not exist)	Stegopterna mutata (Malloch)
2b	a. Chromosomes diploid, male and female larvae	Stegopterna diplomutata Currie & Hunter

References

Adler PH, Currie DC. 2008. Chapter 25. Simuliidae, pp. 825-845 in Merritt RW, Cummins KW, Berg MB, eds. An Introduction to the Aquatic Insects of North America. 4th Ed., Kendall/Hunt Publishing Co., Dubuque, Iowa, USA.
Adler PH, Currie DC, Wood DW. 2004. The black flies (Simuliidae) of North America. Cornell University Press: Ithaca, New York. xv + 941 p.
Moulton JK, Adler PH. 1997. The genus Ectemnia (Diptera: Simuliidae): taxonomy, polytene chromosomes, new species, and phylogeny. Canadian Journal of Zoology 75: 1896-1915
Stone A. 1964. Guide to the insects of Connecticut. Part VI. The Diptera or true flies of Connecticut. Ninth fascicle. Simuliidae and Thaumaleidae. State Geological and Natural History Survey of Connecticut Bulletin 97:1-126.

Page created: November 24, 2013; Last updated: December 3, 2013 (EB)