(Diptera: Therevidae: Therevinae)
Coquillett (1894:98) Type species: Nebritus pellucidus
Coquillett (1894:98) by original designation. Zionea Hardy
(1938:144). Type species: Zionea tanneri Hardy (1938:144)
by original monotypy. Synonymized by Irwin and Lyneborg (1981a:249).
of name: nebrites (Greek, feminine) = like a fawnskin.
The genus Nebritus Coquillett is associated with the genera
Dialineura Rondani and Pallicephala Irwin and Lyneborg
by possessing fine setae on the posterior surface of the middle
coxae, by having the prosternum with fine setae in and around its
central depression (exception P. quebecensis), and with the
scape being wider than the width of the first flagellomere. It is
separated from these two genera in not having the posterolateral
corners of the epandrium strongly projecting nor the epandrium extending
to or beyond the apex of the cerci or hypoproct. At this time, no
definitive sister-group relationship is proposed for Nebritus with
any other therevid genus.
to medium-sized, robust flies. Males more slender and smaller than
(Fig. 1, 13,
29). Eyes dichoptic in both
sexes, facets equal; antenna (Fig. 2, 14,
30), length 1.0-1.4 times head length; scape
variable; pedicel ovate; flagellum awl-shaped, tapered apically;
style subapical, one-segmented; terminal spine short; frons broad,
lateral margins converge dorsally; frontal calli prominent; parafacial
broad, tentorial pit large, distinct, glossy; clypeus concave; maxillary
palp one-segmented (Fig. 3), cylindrical,
apex rounded; setae scattered over entire frons, abundant on gena
and maxillary palp, absent on eyes, parafacial, and clypeus.
Macrosetae: np 2-4, sa 1-3, pa 1, dc 1-2, sc 2. Setae on scutum
variable; prosternal setae white; setae abundant on propleuron,
scattered over entire anepisternum and katepisternum, absent on
remaining pleural sclerites.
(Fig. 4). Hyaline to pale smoky
brown; veins brown; pterostigma indistinct to pale brown; setulae
absent; length of R4 0.9-1.0 times length of R5; cell r4 large;
length of cell r4 2.5-3.1 times width; veins M1, M2, and M3 originate
separately from apical margin of discal cell; cell m3 widely open;
discal cell acute basally; 5 posterior cells; cell cup closed with
short petiole; m-cu/r-m subequal.
Legs. Coxae moderately long; setae elongate, scattered on
anterior and posterior surfaces of coxae; forecoxa with 2-3 black,
Slender to moderately broad, gradually tapering from segment 3 onward;
male dorsum silvery gray pruinose; female dorsum extensively gray
pruinose, some species with a distinct, dark, glossy, anterior band
on various tergites.
Terminalia (Fig. 5-10, 15-20,
Tergite 8 subrectangular to bilobed (Fig.
5, 15, 31)
often strongly constricted medially; sternite 8 (Fig.
7, 17, 33)
rectangular to bilobed, moderately reduced; epandrium (Fig.
5, 15, 31)
shorter medially than wide, its posterolateral corners infolded;
cerci rather large, free, well sclerotized, generally not extending
beyond apex of hypoproct; hypoproct large, extending nearly to anterior
margin of epandrium with a membranous attachment to anterior margin
of dorsal apodeme of aedeagus; hypoproct as a whole well sclerotized,
occasionally keel-shaped apically below cerci; parameral apodeme
(Fig. 6, 16,
32) not attached to aedeagus; distiphallus
(Fig. 8-10, 18-20,
34-36) rather long compared
to rest of aedeagus, downcurved; dorsal apodeme broad, anterior
margin deeply emarginate; ventral apodemes small, not bifurcated
medially; ejaculatory apodeme variable; ventral lobes of gonocoxites
large, spoon shaped, directed obliquely upward, with distinct attachment
to ventral surface of aedeagus; parameral process (Fig.
6-7, 16-17, 32-33)
long and slender; gonocoxites (Fig.
7, 17, 33)
not united ventrally except by a membrane; gonocoxite in lateral
view broadly rounded posteriorly; hypandrium (Fig.
6-7, 16-17, 32-33)
broad throughout, united with anterior margin of gonocoxites for
a rather long distance.
Terminalia (Fig. 11-12, 21-22,
37-38). Tergite 8 subrectangular,
generally longer than wide, posterior margin slightly emarginate.
Tergite 9+10 fused, with strong acanthophorite setae. Cercus subtriangular,
membranous with numerous, fine, moderately long setae. Sternite
8 large; longer than wide; posterior margin with narrow, median
incision. Sternite 9 greatly modified, invaginated above sternite
8 to form internal furca which is closed anteriorly. Sternite 10
membranous; subtriangular; setae short, thick.
Stages. Not previously described. Here described for Nebritus
Adults of Nebritus are found in montane habitats and
coastal sand dunes. They have been collected from 10 January to
27 July on coastal dunes, on wet sand, and along sandy creek bottoms;
on Pinus monophylla Torr. and Frém. in Frém.,
Salix sp., and Adenostoma sp.; and in Malaise traps.
Larvae have been collected in coastal sand dunes.
Nebritus is a Nearctic genus ranging from Baja California
Norte to northern California and eastward to western Nevada and
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from Webb & Irwin 1991a