Description of
Megalinga bolbocera (Osten Sacken)
(Diptera: Therevidae: Therevinae)

Megalinga bolbocera (Osten Sacken) (1887: 162)

Thereva bolbocera Osten Sacken (1887:162): Cole (1923:127); Irwin and Lyneborg (1981a:236).
Thereva bolboceras: Kröber (1914:64) error in spelling.
? Litolinga bolbocera (Osten Sacken): Irwin and Lyneborg (1981a:236).
Megalinga bolbocera (Osten Sacken): New Combination.

Derivation of name bolbos (Greek) = a swelling, bulb; cero < keros (Greek) = horn.

Type Material. The holotype female of Thereva bolbocera Osten Sacken (British Museum (Natural History); MEI 007028) was collected at Presidio [Presidio de Mazatlán, see Selander and Vaurie 1962:47], Mexico, by Forrer.

Diagnosis: Megalinga bolbocera is readily separated from M. insignata in that the males and females have distinctly darker wings with several dark brown spots along R2+3 and two dark brown areas in cell br; the halter knobs are dark brown; the male sternite 8 is deeply emarginate posteriorly, the dorsal and ventral apodemes of the aedeagus are equal in width, and the apical cleft of the distiphallus is short and parallel to the lateral margins of the distiphallus; the female frons is dull yellowish brown with a large circular dark brown area, the furca is shorter in length, and the penis guide is broad and rounded anteriorly.

Description of holotype female
(MEI 007028). Body length 10.8 mm.

Head. Length 1.9 mm. Ocellar tubercle dark reddish brown, with dense yellowish brown microtomentum; ocellar setae dark reddish brown. Eyes dull reddish brown; medial margin straight. Frons (Fig. 10) covered with dense yellowish brown microtomentum with a pair of large dark brown circular areas mediolateral; lateral margins convergent dorsally; setae dark reddish brown, short, scattered. Antenna dull yellowish brown, style dark brown; setae dark yellow, scattered on scape, dark brown over pedicel and scattered basally on flagellum; macrosetae dark brown, scattered on scape; length of antenna 0.4 times head length; length of scape 0.25 mm, 1.4 times width, 3.1 times length of pedicel; length of pedicel 0.08 mm, 0.6 times width; length of flagellum 0.34 mm, 1.8 times width, 1.4 times length of scape; length of basal stylomere 0.05 mm, length of apical stylomere 0.11 mm. Parafacial dark yellowish brown. Genal setae white, becoming dark reddish brown near ventral surface of parafacial. Maxillary palpus clavate, dark yellow; length 0.65 mm, 3.3 times width; setae dark yellow.

Thorax. Macrosetae: np 3, sa 2, pa 1, dc 2, sc 2. Dark reddish brown, dark yellowish brown pruinose; [setae rubbed off specimen]. Postpronotal lobe concolorous with thorax; setae reddish brown. Prosternal setae pale yellow. Propleuron with dark yellow microtomentum, anepisternum, katepisternum, anepimeron, and meron with dull yellowish brown microtomentum; setae white, abundant on propleuron, scattered over entire anepisternum. Scutellum dark yellow, whitish gray pruinose; [setae rubbed off specimen]. Laterotergite dark yellowish brown, gray pruinose; setae pale yellow. Wing. Length 8.6 mm, 2.9 times width; pale smoky brown, densely maculate, with scattered opaque areas; R2+3 with numerous dark brown spots; cell br with two large, dark brown spots medially; posterior cells predominately brown; pterostigma dark brown. Halter dark brown, stalk dark yellow. Legs. [Forelegs absent on holotype]. Mid- and hindcoxa dark yellowish brown; apical macrosetae dark reddish brown. Midfemur pale brown, hind femur pale reddish brown; setae white, appressed, scale-like. Mid- and hindtibia dark yellowish brown. Midtarsomere 1 dark yellowish brown [remaining tarsomeres and hindtarsi absent on holotype].

Abdomen. Dark yellowish brown, concolorous; dorsal setae reddish brown, moderately long with white appressed setae across posterior margin of tergite 1 and laterally along abdomen. Terminalia (Figs. 11-13). Tergite 8 and sternite 8 with medial band of elongate setae. Furca (Fig. 13) subrectangular; length 0.76 mm; posterior and anterior margins broadly rounded; lateral margins sinuate; penis guide elongate, anterior margin broad and rounded.

Variation. Body measurements for females are provided in Table. Variation in thoracic macrosetal counts was not noted. Setae on fore femur white, appressed, scale-like.

Description of Male.

Similar to female with following exceptions. Body measurements for males given in Table.

Head. Ocellar tubercle dark brown, brownish gray pruinose; ocellar setae dark brown. Eyes reddish brown. Frons covered with dull yellowish brown pile with small dark brown area dorsally. Antenna (Fig. 1). Maxillary palpus (Fig. 2) dark yellow, stalk dark reddish brown; setae dark yellow mixed with dark reddish brown setae.

Thorax. Macrosetae: np 3, sa 2, pa 1, dc 2, sc 2. Dark reddish brown with a mixture of short, subappressed dark reddish brown and white setae. Postpronotal lobe dark yellow, white pruinose; setae white. Propleuron white pruinose, anepisternum dark yellowish brown, its anterior half reddish brown; katepisternum, anepimeron, and meron dark yellowish brown; ventral half of meron white pruinose. Scutellum pale brown; setae white to pale yellow. Setae on laterotergite white. Wing (Fig. 3). Legs. Coxae dark yellowish brown, apical macrosetae dark reddish brown. Femora pale brown; setae yellowish brown, appressed, scale-like. Tibiae dark yellow. Tarsi pale reddish brown.

Abdomen. Dorsal setae dark reddish brown, subappressed. Terminalia (Figs. 4-9) dark yellow, parameral process and apical projection of gonostyle dark brown (Figs. 5, 6). Tergite 8 broad, bilobed; posterior margin deeply concave. Sternite 8 moderately reduced, bilobed, deeply constricted medially. Gonocoxite with reduced parameral apodemes. Dorsal and ventral apodemes of aedeagus equal in width (Fig. 8); distiphallus with short apical cleft parallel to apical margins of distiphallus (Fig. 8).

Seasonal Activity. In the specimens examined (N=18), adults were taken from 18 April to 12 December.

Distribution. Megalinga bolbocera in known only from Mexico and El Salvador. (Map)

text from Webb & Irwin 1991b

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