Nebritus
pellucidus Coquillett
(Diptera: Therevidae: Therevinae)
Nebritus
pellucidus Coquillett (1894:98); Cole (1923:18, 1965:349);
Irwin and Lyneborg (1981a:249). Type locality: southern California.
Derivation
of name. pellucidus (Latin) = clear, transparent.
Diagnosis.
Nebritus pellucidus can be readily distinguished from N.
powelli and N. tanneri in that the males and females
have large, glossy, and basally expanded scapes, the ventral half
of which is dark yellow and the dorsal half dark reddish brown;
the length of the scape is greater than 0.8 mm; the length/width
ratio of the scape is less than 3.5; the ventral half of the frons
enlarged to form a distinctive expanded lobe; and the scutellum
is dark reddish brown, subshiny, with a lateral longitudinal pollinose
band.
Description
of lectotype male
(MEI 007041).
Body length 7.0 mm.
Head.
Length 1.3 mm. Ocellar tubercle dark reddish brown, glossy; ocellar
setae black, elongate, scattered. Eyes reddish brown; median margin
of eyes sinuate. Frons broad, ventral half expanded anterolaterally
to form large lobe; pollinose on dorsal two-thirds, ventral third
dark reddish brown, glossy; setae dark reddish brown. Antenna
(Fig. 2) elongate, scape glossy, dark yellow
ventrally, dark reddish brown dorsally, pedicel and flagellum
dark reddish brown; moderately thick, black setae on scape, pedicel,
and scattered basally on flagellum; macrosetae dark reddish brown,
scattered on scape; length of antenna 1.3 times head length; scape
large, expanded basally, tapered apically, length 0.94 mm, 2.9
times width, 6.7 times length of pedicel; length of pedicel 0.14
mm, 0.9 times width; length of flagellum 0.64 mm, 4.0 times width,
0.7 times length of scape; style subapical in lateral cavity,
length 0.10 mm. Parafacial pollinose with median and tentorial
pit areas dark reddish brown, glossy. Genal setae white. Maxillary
palp (Fig. 3) pale yellow; length
0.44 mm, 6.7 times width; setae pale yellow. Postocular setae
dark gold, elongate, lanceolate with scattered black macrosetae.
Thorax.
Macrosetae: np 4, sa 2, pa 1, dc 1, sc 2. Black, gray pruinose;
setae black, fine, scattered with dark gold lanceolate setae on
acrostichal line, laterally, and across anterior margin of scutum;
vittae black, dorsocentral and dorsolateral vittae separated by
pale gold stripe. Postpronotal lobe dark reddish brown, gray pruinose;
setae dark gold, lanceolate. Prosternal setae white. Pleuron dark
reddish brown, dense gray pruinose; setae white, elongate, abundant
on propleuron, scattered over entire anepisternum and katepisternum.
Scutellum dark reddish brown, subshiny with broad, lateral, longitudinal
pollinose band; setae dark gold, lanceolate, clustered laterally.
Laterotergite dark reddish brown, whitish gray pruinose; setae
white.
Wing
(Fig. 4). Length 5.8 mm,
3.9 times width; hyaline; pterostigma pale yellowish brown. Halter
pale yellowish brown.
Legs.
Coxae dark reddish brown, dense whitish gray pruinose, apical
macrosetae dark reddish brown. Femora dark yellow, glossy; setae
on fore and middle femur dark reddish brown, elongate, scattered,
mixed dorsally with white, elongate setae and scattered, white,
short, appressed, scale-like setae; hind femur with short, dark
reddish brown setae mixed dorsally with white, short, appressed,
scale-like setae . Tibiae dark yellow, subshiny, apex reddish
brown. Tarsi dark reddish brown, basal two-thirds of tarsomere
1 dark yellowish brown.
Abdomen.
Dark reddish brown, dense gray pruinose; dorsal setae pale yellowish
gold; lateral setae pale yellow, becoming dark reddish brown on
posterior tergites.
Terminalia.
Dark yellowish orange, glossy (Fig.
5-10). Tergite 8 bilobed, deeply constricted medially. Sternite
8 reduced, subquadrate. Gonocoxite in ventral view without posteromedian
patch of black setae. Dorsal apodeme of aedeagus with large anteromedial
emargination. Ejaculatory apodeme broadly expanded anteriorly.
Variation.
Body measurements given in table.
Thorax variation of macrosetae: np 3-4, 3, sa 2, pa 1, dc 1, sc
2.
Description
of Female
Similar to male with following exceptions. Body measurements given
in table.
Head.
Median margin of eye sinuate.
Thorax.
Macrosetae: np 3, sa 1-2, 2, pa 1, dc 1-2, 1 sc 2. Gold setae
across anterior margin of mesonotum.
Legs.
Tibiae and tarsi dark reddish brown.
Terminalia
(Fig. 11-12). Furca (Fig.
12) quadrate; posterior and anterior margins truncate; lateral
margins sinuate.
Immature
Stages. Unknown.
Seasonal
Activity. In the specimens examined, adults were collected
from 12 April to 13 July. Adults have been collected on Adenostoma
sp., on wet sand, and in Malaise traps.
Distribution.
Nebritus pellucidus ranges from Baja California Norte to
north-central California. (Map)
Text
from Webb & Irwin 1991a
[
Nebritus pellucidus index | Begin
key to Nebritus ]
