Microcercis bispina Foster 2024
Creators: name: Foster, George A.
Publisher: name: Zenodo
Year: 2024
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Diptera
Chloropidae
Microcercis
Microcercis bispina

description: Microcercis bispina (Malloch)
(Figs. 7, 16, 28)
Botanobia (Oscinis) bispina Malloch, 1918: 109 [orig. description]. Type locality: Urbana, Illinois. Deposited Illinois Natural History Survey, Urbana, Illinois (INHS). NEW COMBINATION.
Oscinella bispina.— Sabrosky 1936: 711, 714, 718, 721, 722, 725 [key, discussion].— Sabrosky 1965: 779 [N. Am. catalog, distrib.].
Incertella bispina.— Sabrosky 1980: 721 [new comb.].— Foote 2004: 167 168 [assoc. with Carex in freshwater marsh].— Beaulieu and Wheeler 2005 [recorded from Carex meadows in Quebec, Canada].
Diagnosis.—Ocellar triangle gray to brown; vertex and occiput gray to black tomentose; postpedicel variable, usually yellow ventrally and medially, occasionally lateral surface all brown; prosternum brown; one to two pairs of strong, black, scapular setae between postpronotal lobes; scutum gray to dark brown, tomentose; postpronotal lobe and notopleuron brown, tomentose; pleuron brown to blackish, ventral polished area runs from propleuron to meron unbroken, occasionally a spot of tomentum present on the anterior ventral surface of the katepisternum; femora brown to black, fore and mid tibiae yellow, hind tibia darker; tibial organ light brown; syntergite 1+2 usually brown but may be yellowish, with or without narrow yellow posterior margins; male cerci quadrate lobes; surstylus parallel sided with a posterior curvature, distal tip smooth, rounded, dorsal edge angulate.
Description.—Body length; female: 1.67−1.97mm; male: 1.14−1.70mm.
Head: Ocellar triangle evenly gray to brown tomentose; vertex and occiput gray to black tomentose; frons yellow; scape and pedicel brown, postpedicel variable in color, occasionally entirely brown, usually lateral surfaces with dorsal two-thirds brown, ventral third yellow, medial surfaces often brown only around base of arista, remainder yellow; arista black, pubescent; face, palps, gena, and clypeus yellow tomentose; prementum polished brown, labellum lighter brown to yellow; gena to eye ratio 0.17.
Cephalic chaetotaxy: Fronto-orbital setae light brown; interfrontal setae yellowish; ocellar setae yellow; postocellar setae black; outer vertical setae light brown; inner vertical setae yellow; postocular setae short, fine, yellow; vibrissae yellow; subgenal setae yellow.
Thorax: Prosternum usually brown, may be yellow in specimens with lighter legs; prescutum polished black; scutum evenly gray to dark brown, tomentose; postpronotal lobe and notopleuron brown, gray tomentum; pleuron brown to black, polished, except anepimeron and anepisternum mostly gray tomentose; katepimeron in some specimens with a small spot of tomentum on the anterior ventral surface; mediotergite mostly polished black, gray tomentose laterally; scutellum evenly gray tomentose; subscutellum light gray tomentose, lighter gray than scutellum; wing length 1.19–1.80 mm, hyaline, costal ratios 0.32:0.28:0.15; all coxae polished light brown; all femora somewhat polished brown to black, yellow at extreme distal tips; fore and mid tibiae yellow, slightly infuscated; hind tibia somewhat polished brown on basal half or more, yellow distally; all tarsae yellow except distal 2 tarsomeres brown; femoral organ not imaged; tibial organ light brown.
Thoracic chaetotaxy: One or two pairs strong scapular setae (fig. 7); scutum and scutellum with yellow setae and setulae.
Abdomen: Syntergite 1+2 brown centrally, yellow laterally in some specimens, in others all tergites are brown with or without narrow yellow posterior tergal margins. Male terminalia (fig. 28): epandrium brown tomentose with many setulae, cerci short, quadrate; surstylus short, parallel sided, distal margin smooth, rounded, dorsal tip slightly angulate. Female terminalia including cerci brown.
Distribution.—Nearctic: Canada (Alberta, Manitoba, Newfoundland, Ontario, Prince Edward Island). United States (Colorado, Connecticut, Illinois, Iowa, Kansas, Maine, Massachusetts, Michigan, Montana, Nebraska, New Hampshire, North Dakota, Ohio, Pennsylvania, South Dakota, West Virginia, Wisconsin).
Discussion.—This species is like M. albipalpis in having an entirely polished ventral pleuron, only the anepisternum and anepimeron are tomentose but occasionally the anterior surface of katepisternum may show some tomentum. It differs from M. albipalpis in having one, rarely, two, pairs of strong, black scapular setae, a character shared by one other Microcercis species, M. dorsata.
Many mid-west to western specimens are darker in overall color than the eastern material examined. The polished ventral portions of the pleuron are nearly black in some western specimens while more brownish in the eastern material.
Foreleg color can also vary. I have seen a few specimens with entirely yellow forelegs.
description: Published as part of Foster, George A., 2024, Revision of Nearctic Microcercis Beschovski (Diptera: Chloropidae), with Synonymy of Incertella Sabrosky, pp. 401-439 in Zootaxa 5481 (4) on pages 408-409, DOI: 10.11646/zootaxa.5481.4.1, http://zenodo.org/record/12780285