Catalogue of the Nearctic genera

Keys Comparison Catalogue Terminology Notes

Apocleinae
Amblyonychus
Eccritosia
Furcilla
Mallophora
Megaphorus
Nevadasilus
Proctacanthella
Proctacanthus
Promachella
Promachus
Efferia-group
Albibarbefferia
Aridefferia
Carinefferia
Efferia
Nerax *
Pogonioefferia
Triorla
Tuberculefferia

Nerax Hull, 1962
[Apocleinae: Efferia-group]

Neotropical	Nearctic	Palaearctic	Afrotropical	Oriental	Australian & Oceania
	typ.loc.

Description:	Hull, F.M. (1962): Robber flies of the world. - Bulletin of the United States National Museum 224 (1, 2): 1-907 [476]; Washington.
Type species:	Asilus aestuans Linnaeus, 1763: 413

Literature:	Coquillett, D.W. (1893): A new asilid genus related to Erax. - The Canadian Entomologist 25: 175-177; Ottawa [key]. Hine, J.S. (1919): Robber flies of the genus Erax. - Annals of the Entomological Society of America 12(2): 103-157, pls. 7-9; Columbus [key]. Wilcox, J. (1966): Efferia Coquillett in America North of Mexico (Diptera, Asilidae). - Proceedings of the California Academy of Sciences 34: 85-234; San Francisco [key]. Parks, L. (1968): Synopsis of robberfly genera allied to Efferia and Eicherax, including a new genus. - Pan-Pacific Entomologist 44: 171-179; San Francisco [key]. Bullington, S.W. & Lavigne, R.J. (1984): Description and habitat of Efferia kondratieffi sp. nov. with notes on Efferia aestuans (L.) (Diptera: Asilidae). - Annals of the Entomological Society of America 77: 404-413; Columbus [key].

Nearctic species:

Nerax aestuans (Linnaeus, 1763)

Nerax antiphon (Walker, 1849)

Nerax apicalis (Wiedemann, 1821)

Nerax aurimystaceus (Hine, 1919)

Nerax beameri (Wilcox, 1966)

Nerax belfragei (Hine, 1919)

Nerax femoratus (Macquart, 1838)

Efferia kondratieffi Bullington & Lavigne, 1984 [new combination is necessary]

Nerax kansensis (Hine, 1919)

Nerax macrolabis (Wiedemann, 1828)

Nerax prairiensis (Bromley, 1934)

Nerax slossonae (Hine, 1919)

Nerax stylatus (Fabricius, 1775)

Nerax tabescens (Banks in Hine, 1919)

Nerax aestuans (Linnaeus, 1763)

- male -

- female -

Key to the species

Founded on: Wilcox, J. (1966): Efferia Coquillett in America North of Mexico (Diptera, Asilidae). - Proceedings of the California Academy of Sciences 34: 85-234; San Francisco. [amended]

Unrecognized species: Nerax antiphon (Walker, 1849) from Georgia; Nerax macrolabis (Wiedemann, 1828) from Kentucky; Nerax stylatus (Fabricius, 1775) (= Erax haitensis Macquart, 1848) from Florida, and females of Nerax slossonae (Hine, 1919).

	Males.
	Females.

	Legs entirely shining black. Wings hyaline. Costa not dilated. Tergites 5-7 silvery pollinose. Hypopygium black with black hairs. Epandria with a broad apical flange. Length 14 mm . . . . . Nerax slossonae (Hine, 1919) [FL]
	At least the tibiae distinctly reddish.

	Apical half of tergites 2 and 3-7 largely white pollinose with white parted hairs. Costa not dilated. Length 12-16 mm . . . . . Nerax beameri (Wilcox, 1966) [TX]
	At most tergites 4-7 largely white pollinose and without white parted hairs on any segments.

	Costa more or less dilated. Subcostaal cell# light to dark brown. Sternites with fine erect white hairs.
	Costa not dilated. Subcostal cell hyaline. Sternites 3-5 or 6 with clumps of short black hairs.

	Six or more marginal scutellar bristles. Tergites 5-7 silvery pollinose.
	Usually two scutellar marginal bristles. At most tergites 6-7 silvery pollinose.

	Scutum anteriorly with very short black hair. Length 26-30 mm . . . . . Nerax femoratus (Macquart, 1838) [SC, NC, LA, FL, GA]
	Hairs of anterior scutum as long or longer than scape.

	Epandria 2.7-3.7 mm long, apices either as in Fig. 11 and 12 or in Fig. 13 and 14 (Bullington & Lavigne, 1984: 407). Length 10-18 mm (Wilcox, 1966: 14-28 mm) . . . . . Nerax aestuans (Linnaeus, 1763) [PA, ND, WY, CO, NM, SD, NE, KS, OK, TX, MN, IA, MO, AR, LA, WI, IL, MS, MI, IN, KY, TN, AL, GA, FL, OH, WV, VA, NC, SC, NY, NH, MI, MD, UT, ONT]
	Epandria 2.1-2.7 mm long from ventrobasal knob to dorsoapical tooth, apices either as in Fig. 6 and 7 (Bullington & Lavigne, 1984: 405). Length 9-14 mm . . . . . Efferia kondratieffi Bullington & Lavigne, 1984 [KS, OK, TX]

	Tergites 6-7 silvery, 6 sometimes with a narrow spoat basally, 2-5 black dorsally. Length 14-22 mm . . . . . Nerax apicalis (Wiedemann, 1821) [GA, TX, LA, MS, AL, FL, SC, NC]
	Tergite 7 only, wholly silvery, 2-6 largely brown or black dorsally.

	Sides and usually posterior margin of tergite 6 white pollinose, dorsum of 2-6 black with mostly short black hairs. Hypopygium black with black hairs. Epandria at apex with tuft of short black hairs. Fringe on gonocoxite of uniform width and as long as scape. length 15-23 mm . . . . . Nerax tabescens (Banks in Hine, 1919) [FL, GA]
	Sides of tergites 2-6 grayish pollinose, dorsum brown with mostly short white hairs. Hypopygium brown, in part white haired. Fringe longer at base than apex and margined with white hairs. Length 15-19 mm . . . . . Nerax kansensis (Hine, 1919) [VA, PA, MD, NJ, NY]

	Mystax yellowish. Gonocoxite with a dense fringe of brownish hairs, longer than scape, pedicel, and postpedicel combined. Length 13-15 mm . . . . . Nerax aurimystaceus (Hine, 1919) [KS, OK, TX]
	Mystax black with a few white hairs intermixed. Gonocoxite with a sparse fringe of brown and black hairs subequal in length to scape and pedicel combined. Length 10-14 mm . . . . . Nerax belfragei (Hine, 1919) [TX, OK?]

	Ovipositor 6 mm long or longer.
	Ovipositor at most 5.5 mm long, usually shorter.

	Mystax black, some white hairs intermixed. Tibiae largely reddish. Abdomen gray pollinose, dorsum 2-4 black. Ovipositor as long as abdominal segments 4-7. Length 10 mm . . . . . Nerax belfragei (Hine, 1919) [TX, OK?]
	Larger species, 14-30 mm in length.

	Hairs anteriorly on the scutum shorter than pedicel. Tibiae and tarsomeres dark reddish. Ovipositor 7.3 mm long . . . . . Nerax femoratus (Macquart, 1838) [SC, NC, LA, FL, GA]
	Hairs anteriorly on the scutum as long as antennal scape. Tips of the tibiae and tarsomeres black. Ovipositor 6.0 mm long . . . . . Nerax aestuans (Linnaeus, 1763) [PA, ND, WY, CO, NM, SD, NE, KS, OK, TX, MN, IA, MO, AR, LA, WI, IL, MS, MI, IN, KY, TN, AL, GA, FL, OH, WV, VA, NC, SC, NY, NH, MI, MD, UT, ONT]

	Mystax yellowish with at most 8 black bristles above. Ovipositor broad, 2.7 mm long . . . . . Nerax aurimystaceus (Hine, 1919) [KS, OK, TX]
	Mystax white with 15 or more black bristles above. Ovipositor at least 3.7 mm long.

	Hairs on anterior scutum as long or longer than scape. Ovipositor 4.0 mm or less in length.
	Hairs on anterior scutum shorter than scape. Ovipositor 4.1 mm long or longer. Tergites 2-5 or 6 black with mostly short black hairs, siedes and posterior margins gray pollinose.

	Tergites 2-5 gray pollinose and mostly short white haired. Ovipositor 4.0 mm long . . . . . Nerax kansensis (Hine, 1919) [VA, PA, MD, NJ, NY]
	Tergites 2-5 black dorsally.

	4 marginal scutellar bristles. Ovipositor 3.7 mm long . . . . . Nerax beameri (Wilcox, 1966) [TX]
	6 marginal scutellar bristles. Ovipositor 3.2-4.4 mm long . . . . . Efferia kondratieffi Bullington & Lavigne, 1984 [KS, OK, TX]

	Ovipositor gradually narrowing apically, 4.1-5.5 mm long. Narrow dorsum and posterior margin of tergite 7 brownish pollinose . . . . . Nerax tabescens (Banks in Hine, 1919) [FL, GA]
	Ovipositor narrowed byond basal one-third, 4.1-4.5 mm long. Tergite 7 shining black . . . . . Nerax apicalis (Wiedemann, 1821) [GA, TX, LA, MS, AL, FL, SC, NC]