Isomyia iris James 1970

Isomyia iris

MALE.—Occiput, ocellar triangle, frons, parafacials, and a large area on anterior part of gena black; face yellow, facials, cheek groove, rest of gena, and lunule orange to orange-yellow; pollen cinereous, densest on parafrontals, parafacials, and occipital orbits, becoming golden on cheek groove, much of gena, and face, only moderately dense on gena, the entire ground color showing through; frontalia on upper half golden pollinose; lunule apparently shining, yet when viewed from behind upper part distinctly yellow-pollinose. Bristles, hair and setulae black to blackish brown, those of occiput yellowish, becoming yellowish brown to brown below; setulate of parafacials moderately long, in two fairly well defined rows. Frontals, 8 or 9, row continued with a few setulae above to a point about half way from antennal base to ocelli; lunule without setulae. Width of frons at narrowest area less than diameter of anterior ocellus, frontale completely obliterated at narrowest. Antenna orange, flagellum largely yellow, upper surface brown; arista orange at base, then yellow, becoming brown on apical half; rays brown. Measurements in micrometer units: head width 275; width of frons at minimum, 4, at vertex, 30; distance between vibrissae, 55; vibrissae to oral margin 35; oral margin to lower margin of lunule, 105; parafacial at antennal base, 15, at cheek groove, 17; width of gena 45; eye height 195; antennae separated by 8; length of pedicel 20, of flagellum, 43.

Mesonotum black centrally, with dull bronze reflections when seen through pollen; broad sides and prescutellar area deep metallic blue-green, more of a deep green in supra-alar area and in front of scutellum, deep blue to purple elsewhere; central part of prescutellar green area forming a triangle from postalar callus almost to suture, where it is continued by a vitta between acrostichal rows to anterior presutural acrostichal; dorsocentrals set on a narrow purple vitta with violet reflections; black areas strongly cinereous pollinose, as viewed from behind, leaving a narrow black vitta between each acrostichal and dorsocentral row and a large triangular area between dorsocentral row and posthumerals without pale pollen; areas of contact between black and metallic areas merging in proper light from green to deep blue to purple to violet (this suggests the name iris, “rainbow”). Scutellum and pleura deep blue with purplish reflections; under side of scutellum cinereous pollinose on median third; pollen elsewhere cinereous to brown, generally not conspicuous except on sternopleuron. All thoracic bristles, setulae, and most hairs black to brownish black; hairs of mesopleuron especially long and dense, especially on upper part, where they tend to obscure the usual black setulae; these hairs appear brownish under certain lights; posterior mesopleural fringe brown; some black erect hairs on posterior declivity and under sides of scutellum. Covering of anterior and posterior spiracles deep brown. Acrostichals, 2, 3, anterior postsutural weak; dorsocentrals, 2, 4; scutellars, 3 lateral 1 discal; humerals 3; pteropleural, 1; no accessory propleural or stigmatal.

Legs black, with black setulae and bristles; front femur with strong purplish reflections, almost appearing purple, posteriorly and on basal part anteriorly, other femora with limited purplish reflections posteriorly; tibiae more brownish black, front tibia in places yellowish brown. Middle tibia without a ventral. Wing almost hyaline, very slightly brownish; bend of M1 abrupt but not angular. Basicosta brown to dark brown, darker anteriorly. Halteres yellow. Squamae wholly and uniformly brown except rim yellowish.

Abdomen deep blue with strong purple reflections; basal part of first tergum dorsally and broad apices of second and third, also a median vitta on first three, black; ventral aspects of second and third becoming bronze medially. Pollen of dorsal surface inconspicuous, visible as thin cinereous pollen when viewed posteriorly; that of ventral surface much more apparent, dense on first tergum and toward inner margins of second and third, where it forms tessellated patterns. First sternum apparently black, second purple, densely cinereous pollinose. Bristles and setulae mostly black; hairs of first and second sterna white, but second also, in addition to apical bristles, with numerous strong black setulae that appear as fine bristles. Genitalia not dissected. Length, 11 mm.

FEMALE.—Unknown.

HOLOTYPE.—, Philippine Islands, Mindanao, Zamboanga; Baker; USNM 70767.