Brachygasterina fulvohumeralis ( Malloch, 1922 )

De Carvalho, C. J. B. & Pont, A. C., 2006, Taxonomy, cladistics and biogeography of the South American genus Brachygasterina Macquart (Diptera: Muscidae), Zootaxa 1151, pp. 1-26 : 8-10

Brachygasterina fulvohumeralis ( Malloch, 1922)

Euphaonia fulvohumeralis Malloch, 1922: 271 .

Diagnosis

This species is very characteristic among the species of Brachygasterina because of the striking orange­yellow colour of humeral callus and prothoracic spiracle, and notopleuron dull orange. No obvious dusting on thorax or abdomen. Fore tibia with a strong posterior median seta.

Redescription

Female. Head missing in the holotype, which is still the only known specimen. The following characters are taken from Malloch’s (1922) original description of his Euphaonia fulvohumeralis n.gen., n.sp.: head black, opaque, fronto­orbital plates and face with whitish pruinosity; eyes short­haired; frons one­third of head­width; two orbital setae, one directed backwards and outwards, one directed inwards, without proclinate orbitals; interfrontal setae present, crossed; arista short pubescent, the hairs not longer than its basal diameter; parafacial linear; gena as high as half width of first flagellomere, the latter 1.5 times as long as pedicel.

Thorax. Ground­colour subshining dark metallic blue, hardly dulled by pruinescence in posterior view; humeral callus and prothoracic spiracle orange­yellow, notopleuron dull orange. Mesonotum with a single median white presutural vitta running over the acrostichal rows as far as suture, otherwise undusted. 2+3 developed acrostichals; 2 strong posterior intra­alars; prealar very strong, longer than anterior notopleural seta; notopleuron bare apart from the setae. Scutellum laterally setulose; with strong apical and basal setae, two weaker laterals placed more on disc, and a weaker basal. One strong proepisternal seta and 3–4 setulae; 2 strong proepimeral setae and many long setulae. Katepisternals 1+2. Katatergite pilose.

Legs. Only three legs remaining on holotype, all three detached and gummed to mount (left fore leg, right mid leg, right hind leg). Black. Fore tibia with a posterior seta. Mid femur with 1 short anterior and 2 posterior preapical setae. Mid tibia with 4 posterior setae, without anterodorsal or ventrals. Hind femur with 3 strong anteroventral setae in apical third, bare on posteroventral surface; 3 well spaced anterodorsal and 4 short anteroventral setae; dorsal and anterodorsal preapicals strong, without posteroventral apicals.

Wing. Clear, somewhat smoky towards base, veins brown. Veins bare, except costa. Crossvein dm­cu straight. Vein M running straight to wing­margin. Calypters brown, lower one slightly longer than upper one. Knob of haltere dark brown.

Abdomen. Subshining metallic blue, without dust. Sternite 1 bare.

Measurements (n=1): Wing length, 7.0 mm.

Remarks

The holotype is in poor condition (see also Malloch, 1934): head, right fore leg, left mid leg and left hind leg missing; the other legs glued to the staging mount; abdomen loosely attached to thorax. The holotype is labelled with an old handwritten label “Pt. Fam.”; a printed label “Port Famine, / T. del Fuego. / C. Darwin.”; a further label “1863–44. [handwritten] / Darwin Coll. [printed]”; it is also labelled as Type by Malloch, and with the combination in Brachygasterina by Carvalho.

Geographic distribution

Chile.