Indascia gigantica Reemer

Reemer, Menno & Stahls, Gunilla, 2013, Generic revision and species classification of the Microdontinae (Diptera, Syrphidae), ZooKeys 288, pp. 1-213 : 99-100

Indascia gigantica Reemer sp. n. Figs 107-112

Type specimens.

HOLOTYPE. Adult male. THAILAND. Label 1: "THAILAND: Chiang Mai, Doi Inthanon NP / Checkpoint 2, 18°31.554'N, 98°29.94'E 1700 m / Malaise trap 8-15.v.2007, Y. Areeluck leg. T1832"; label 2: "Syrphidae / T1832 / W. Porras, 08"; label 3: "Voucher code M. Reemer / 319 / DNA voucher labcode MZH:Y0909". Coll. QSBG.

Diagnosis.

Within Indascia , this exceptionally large species shares the presence of a posterior appendix on vein R4+5 only with Indascia spathulata sp. n. From that species, Indascia gigantica differs by tergite 2 being about 1.5 times as long as wide, and the basoflagellomere being 2 times as long as wide.

Description (based on holotype).

Adult male. Body size: 9.5 mm.

Head. Face occupying about 1/4 of head width in frontal view; black; entirely silvery white pilose. Gena black, white pilose. Oral margin not produced. Frons and vertex black; golden pilose, except for few black pile at ocellar triangle. Occiput black; yellowish pilose dorsally, white pilose ventrally. Eye bare. Antennal fossa about as high as wide. Antenna black; antennal ratio approximately as 4:1:4.

Thorax. Thorax black, except postalar callus and metanotum yellowish and posterior pleurites narrowly brownish along margins. Mesoscutum mixed golden and black pilose, with white pile at and around notopleuron. Postpronotum whitish pilose. Postalar callus black pilose anteriorly, yellow pilose posteriorly. Scutellum somewhat triangular, without calcars; black pilose dorsally, golden pilose along lateral and posterior margins. Anepisternum with deep sulcus separating anterior and posterior part; entirely long white pilose. Anepimeron entirely long white pilose. Katepisternum long white pilose dorsally, bare ventrally. Katatergum long microtrichose, anatergum short microtrichose. Calypter greyish. Halter pale yellow.

Wing: Hyaline, subtly darkened around apical crossveins and appendix of vein R4+5; microtrichose, except bare on cell sc, posterobasal 2/3 of cell c, basal 1/4 of cell r1, most of cell br except microtrichose along vena spuria, basal 5/6 of cell bm and basal 1/2 of cell cup.

Legs: Mid femur blackish, gradually turning yellow at apical 1/4; black pilose. Mid tibia yellow at basal 1/2, blackish at apical 1/2; black pilose. [Mid tarsus and other legs missing in holotype.] Coxae and trochanters black.

Abdomen. Tergites bronze-black. Tergite 1 long white pilose laterally, short black pilose sublaterally, bare medially. Tergite 2 with long white pile laterally on anterior 1/2, short black pilose over dorsal surface, short golden pilose narrowly along posterior margin. Tergite 3 long white pilose laterally on anterior 1/2, short black pilose over dorsal surface, long golden pilose on posterior 1/3. Tergite 4 with pilosity more or less as tergite 3, but much more sparse. Sternites blackish brown; sternite 1 bare; sternites 2-4 short black pilose anteriorly, long white pilose posteriorly. Male genitalia as in Fig. 112.

Female. Unknown.

Etymology.

The specific epithet (adjective) refers to the large size of this species in comparison with other known species of Indascia .

Notes.

In the holotype, the only specimen available, the posterior appendix of vein R4+5 is composed of two short vein stumps, which are confluent at their apices, forming a triangle with part of vein R4+5. This is unusual, although similar aberrations can be found in single specimens of Microdontinae from different genera and species groups. Whether the venation as found in the holotype is representative of this species remains uncertain.