Dideopsis aegrota (Fabricius, 1805):243

Dideopsis has by most authors been included in Asarkina, probably because of the anterior mesonotal pile collar in both genera. The only other striking similarity between the two genera is in the arrangement of the katespiternal pile. In head shape, wing markings, pilosity of meron and metaepisternum, pile of metacoxa, abdominal pattern, and particularly in the structure of the male genitalia there is no particular indication of relationship. Dideopsis, however, shows no strong affinities with other genera. No other genus in the Syrphini has a broad dark vitta covering 1/3 or more od the wing (from Vockeroth 1969).

Dideopsis aegrota (Fabricius, 1805).

Fabricius, J.C. (1805) Systema antliatorum secundum ordines, genera, species... xiv + 15-372 + [1] + 30 pp. C. Reichard, Brunsvigae [=Brunswick].

Adapted from Vockeroth (1969).

Large species with moderately broad abdomen bearing broad yellow fasciae and with very broad brown vitta across middle of wing.

Head: Eye bare. Face very slightly receding below, oral opening about 2.5 times as long as broad. Face pale yellow, white pollinose, with rather broad black median stripe extending to antennae. Antenna with basoflagellomere slender, sub oval, 1.3 times as long as broad and 1.3 times as long as first two segments combined (male) or distinctly swollen, tapering slightly to apex, 1.5 times as long as broad and 1.7 times as long as first two segments combined (female).

Thorax: Scutumshining black, the notopleural area and sometimes a narrow postsutural margin distinctly whitish-yellow pollinose. Scutellum yellow. Pleura dark brown to black, sub shining, with posterior part of anpisternum, anterior part of anepimeron, and dorsalpart of katepisternum densely white pollinose, sometimes slightly paler in ground colour. Scutum with anterior collar of long erect pile. Dorsal and ventral katepisternal pile patches widely separated throughout. Anterodorsal corner of katepisternum with a tuft of pile. Metasternum with long black pile posteriorly. Posteromedian apical angle of metacoxa with a strong tuft of pile. Wing with broad dark brown vitta across median third or slightly more and with base of wing dark brown or with basal 2/3 of wing dark brown; wing apex beyond brown vitta clear. Vein R4+5 very broadly and indistinctly dipped into cell R4+5.

Abdomen oval, not excessively broad, flattened above, with strong margin from near base of tergum 2 to apex of tergum 5. Tergum 2 with a pair of large, oval, sometimes subconfluent, yellow maculae which reach the anterior and lateral margins broadly; terga 3 and 4 with anterior half or slightly less yellow, otherwise black, the yellow fasciae slightly but distinctly sinuous posteriorly. Sterna yellow, 2 to 5 with broad apical or subapical black fascia which extend over the lateral membrane.

Male genitalia: Surstylus broad, short, more strongly broadened and broadly rounded apically, with very abundant setae on inner surface. Sternite 9 slightly narrowed posteriorly, rather strongly produced ventrad below, posteroventrally with a broad deep anteriorly narrowed emargination, laterally with a few short but distinct scattered setae. Superior lobe thick basally and ventrally, semicircular in profile but with posteroventral margin produced dorsad as a strong projecting tooth, ventrolateral margin with a few minute setae. Aedeagal base in the form of a shallow trough with widely divergent, depressed, broadened, dorsal margins and a pair of slender, slightly depressed, subparallel, widely separated, ventrolateral processes. Distal portion of aedeagus. moderately compressed, bent rather strongly ventrad, with depressed sub circular posterodorsal process at the bend, the apex membranous, not inflated, with a few rather stout spicules anteriorly.

Synonyms:

Syrphus fascipennis Macquart, 1834: 537.

Didea ellenriederi Doleschall, 1857: 407.

Syrphus infirmus Rondani, 1875: 423.

Asarkina pura Curran, 1928: 230.

Dideopsis hemipennis Hull, 1945: 212.

Eristalis aegrotus Fabricius, 1805: 243.

GenBank accession number for this species are: protein-coding COI gene (EF127333), rRNA 28S gene (EF127414), 16S gene (AF154775; AF154774; AF154773) and 12S gene (AF154699; AF154698; AF154697).

Body length: 9.6 to 13.3 mm.

Dideopsis is a member of the tribe Syrphini. Mengual et al. (2008) included Dideopsis aegrota in their molecular analysis, and Dideopsis was resolved as sister group of Eriozona syrphoides and Dideoides coquilletti.

D. aegrota larvae have been reported feeding on aphids, particularly Aphis craccivora, A. gossypii, A. spiraecola, Astegopteryx nipae, Brevicoryne brassicae, Ceratovacuna lanigera, Lipaphis erysimi, Pentalonia nigronervosa, Pseudoregma? sundanica, Rhopalosiphum maidis, Toxoptera aurantii, T. citricida, and T. odinae.

Described from China, Dideopsis aegrota is known from Nepal, SE Asia, New Guinea and Australia (NT, QLD).