Stipomorpha trigoniformis (Shannon, 1927)

Reemer, Menno, 2013, Taxonomic exploration of Neotropical Microdontinae (Diptera: Syrphidae) mimicking stingless bees, Zootaxa 3697 (1), pp. 1-88 : 72-73

Stipomorpha trigoniformis (Shannon, 1927)

Figs 216–219 , 249 .

Microdon (Ubristes) trigoniformis Shannon, 1927: 19 . Type locality:

Studied type specimens. HOLOTYPE. BRAZIL. Male. Label 1 (small, round, red-bordered): " Holotype "; label: "Villa Nova", other side: "55 37"; label 3: " Microdon Ubristes trigoniformis Snn.". Coll. BMNH.

Additionally studied specimens. FRENCH GUYANA: 1 male, Kaw mountains, 04°33.562'N – 52°12.425'W, 21.X.2002, leg. V. Soon, coll. RMNH.

Redescription (based on holotype)

Adult male. Body size: 7.5 mm.

Head. Face occupying 1/4 of head width in frontal view; shining black with yellow lateral margins, the black part occupying 2/3 of face; face with white pilosity, bare on median 1/3. Gena hardly developed, directly bordering oral cavity. Oral margins black, laterally produced and anteriorly notched. Frons and vertex black and short black pilose, except for bare triangular part posterior to lunula. Occiput black; black pilose on dorsal half, white on ventral half. Eye sparsely and short pilose, with pili about as long as ommati diameter, appearing bare under low magnification. Antennal fossa about as wide as high. Antenna blackish brown; antennal ratio 3:1:3.5; basoflagellomere parallel-sided with narrowly rounded apex; arista slender, about 3/5 of length of basoflagellomere.

Thorax. Black. Postpronotum, scutum, postalar callus and scutellum short black pilose, except a few pale pile along transverse suture. Scutellum semicircular, without calcars. Anepisternum more or less flat, pilose anterodorsally. Anterior part of anepimeron pilose dorsally. Katepisternum and katepimeron bare. Calypter grey, halter blackish.

Wing: hyaline, with faint brownish hue all over; microtrichose except bare on basal 2/3 of cell br, basal 1/8 of cell bm, anterobasal 1/4 of cell cup.

Legs: brownish black, except fifth tarsomeres of all tarsi yellow. Legs black pilose, except tibiae pale pilose basally (extent hard to assess in holotype); pile on hind-tibia a little longer than half the width of the tibia. First tarsomere of hind- tarsus as long as 1/3 of length of hind-tibia, a little wider than apex of tibia, 1.5 times as long as wide (dorsal view). Coxae and trochanters black pilose.

Abdomen. Blackish brown. Second segment slightly wider than thorax, widest point at anterior 1/3; third and fourth tergites strongly narrowing. Tergite 1 black pilose anterolaterally; with anteromedian smooth, concave area. Tergite 2 black pilose anterolaterally, pale pilose laterally and dorsally. Tergite 3 and 4 pale pilose. Sternite 1 bare. Genitalia as in 249.

Female. Unknown.

Diagnosis. From other Stipomorpha -species with a black thorax, S. trigoniformis can be recognized by the following characters: katepisternum bare, alula entirely microtichose, wing without whitish transverse fascia.

Distribution. Known from Brazil and French Guyana.

Figures

FIGURES 212 – 221. 212 – 215. Stipomorpha tenuicauda female (holotype). 212. habitus dorsal; 213. habitus lateral; 214. head frontal; 215. head dorsal. 216 – 219. Stipomorpha trigoniformis male (holotype). 216. habitus dorsal; 217. habitus lateral; 218. head frontal; 219. wing. 220 – 221. Stipomorpha wheeleri male (paratype). 220. habitus dorsal; 221. habitus lateral.

FIGURES 246 – 251. Stipomorpha, male genitalia latera. 246. S. simillima (holotype); 247. S. spuria (holotype); 248. S. tenuicauda (Bolivia, coll. RMNH); 249. S. trigoniformis (holotype); 250. S. wheeleri (paratype); 251. S. zophera (holotype).