Stipomorpha mixta (Curran, 1940)

Reemer, Menno, 2013, Taxonomic exploration of Neotropical Microdontinae (Diptera: Syrphidae) mimicking stingless bees, Zootaxa 3697 (1), pp. 1-88 : 64-66

Stipomorpha mixta (Curran, 1940)

Figs 191–195 , 244 .

Microdon mixtus Curran, 1940: 6 .

Studied type specimens. HOLOTYPE. GUYANA. Female. Label 1 (small round, red-bordered label): " Holotype "; label 2: "British Guyana: Cuyuni R., Kamaria Landing. 22.XI.1929. Oxf. Univ. Expedn. B.M. 1929- 485."; label 3: "6250"; label 4 (red): " Microdon mixtus Curran Holotype female"; label 5: " Microdon mixtus Curran Det. C.H. Curran "; label 6: "Note 389". Coll. BMNH.

Additionally studied specimens. FRENCH GUYANA: 1 male & 1 female, Kaw Mountains, 04°32.893’N – 52°10.245’W, 30.XII.2002, leg. V. Soon, coll. RMNH; GUYANA: 1 male, Kurupkari: 4°40'N, 58°40'W, sept.-nov. 1992, leg. BMNH(E)2006-132, coll. BMNH; SURINAM: 1 female, Brownsberg, 04°56'45"N – 55°10'59"W, 2.VI.2006, leg. M. Reemer, coll. RMNH.

Redescription (based on holotype)

Adult female. Body size: 8.5 mm.

Head. Face occupying almost 1/3 of head width in frontal view; shining yellow with yellow pilosity, a little longer around oral margin. Gena yellow. Oral cavity with lateral margins not produced and not notched anteriorly. Frons black; yellow pilose, except for bare triangular part posterior to lunula. Vertex black; yellow pilose. Occiput black; black pilose dorsally, yellow pilose laterally, gradually getting white ventrally. Eye very 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 brown, scape yellow on basal 3/4. Antennal ratio 6:1:6; basoflagellomere parallel-sided with narrowly rounded apex, with sensory pit located at 2/3 from base, just ventrad of a groove that ranges from the base of the arista to the apex. Arista slender, about 2/3 of length of basoflagellomere.

Thorax. Yellow, except blackish brown on scutum, leaving wide yellow lateral margins. Scutum yellow pilose, except for lateral patches of dark pile posterior to transverse suture. Postpronotum, postalar callus and scutellum yellow and yellow pilose. Scutellum without calcars. Anterior and posterior part of anepisternum not differentiated; anterior part yellow pilose, posterior part bare. Anepimeron yellow pilose dorsally. Katatergum and anatergum pilose and microtrichose, respectively. Other pleurae bare. Calypter and halter yellow.

Wing: hyaline, tinged with yellow in and posterior to costal cell and in and posterior to pterostigma. Microtrichose except bare on posterobasal 1/4 of cell br, basal 1/2 of cell bm.

Legs: Yellow and yellow pilose, except with long black pile on apical 1/2 of hind-etatibia and dorsally on hind tarsi. Hind-tibia strongly widened, widest point around 1/2. Coxae and trochanters yellow and yellow pilose.

Abdomen. Yellow. Tergite 2 wider than thorax, widest at posterior margin; tergites 3 and 4 about as wide as thorax. Tergite 1 and 2 black pilose. Tergite 1 with anteromedian smooth, concave area. Tergite 3 black pilose, with some yellow pile laterally. Tergite 4 black pilose anteriorly and medially (in the shape of a T with a wide cross-bar), yellow pilose laterally and posteriorly. Sternite 1 narrow and bare, separated from sternite 2 by a membrane of about the width of sternite 1. Sternite 2 pilose, laterally twice as wide as medially, separated from sternite 3 by a membrane of about the median width of sternite 2. Sternite 3 and 4 pilose, not separated by membrane

Male. (See also notes below!) Body size: 7 mm. As female, except for following characters (based on 1 specimen). Face occupying about 1/4 of total head width in frontal view. Frons yellow anteriorly, black posteriorly; mixed yellow and black pilose. Antenna yellowish brown; basoflagellomere slightly longer than scape; antennal ratio approximately as 4:1:5. Wing bare on basal 1/3 of cell r1, entirely on cells R and BM, basal 1/3 of cell cup. Tergite 3 yellow pilose, except black pilose laterally. Tergite 4 yellow pilose along anterior margin, on median 1/3 and along posterior margin, black pilose on lateral 1/3. Genitalia as in fig. 243.

Diagnosis. From other Stipomorpha species with a yellow scutellum and abdomen, S. mixta differs by the following characters: posterior part of anepisternum bare, alula entirely microtrichose, wing uniformly hyaline, vertex black, tarsi entirely yellow, anterior margin of tergite 2 not curled around tergite 1 laterally.

Notes. A very variable species in colouration of pilosity, antennal ratio and extent of microtrichosity on wings. Possibly this variability indicate that there is more than one species involved, but this could not be determined with the available material.

The female specimen from Surinam was captured after the collector saw it tumbling down (from the canopy?) on shrub leaves along a narrow path in dense primary forest.

Distribution. Known from Guyana, Surinam and French Guyana.

Figures

FIGURES 186 – 200. 186 – 187. Stipomorpha micromidas male (Costa Rica, coll. INBIO). 186. habitus dorsal; 187. habitus lateral. 188 – 190. Stipomorpha micromidas female (holotype). 188. habitus dorsal; 189. habitus lateral; 190. head lateral. 191 – 195. Stipomorpha mixta. 191. male (Surinam, coll. RMNH), habitus dorsal; 192. female (holotype), habitus dorsal; 193. female (holotype), habitus lateral; 194. female (holotype), head frontal; 195. female (holotype), head lateral. 196 – 200. Stipomorpha panamana male (holotype). 196. habitus dorsal; 197. habitus lateral; 198. head frontal; 199. head lateral; 200. wing.

FIGURES 240 – 245. Stipomorpha, male genitalia. 240. S. mackiei (Surinam, coll. RMNH); 241. S. maculipennis (holotype); 242. S. mendax (holotype); 243. S. micromidas (Costa Rica, coll. INBIO); 244. S. mixta (Guyana, coll. BMNH); 245. S. panamana (holotype).