Microcercis bispina (Malloch), 2024

Foster, George A., 2024, Revision of Nearctic Microcercis Beschovski (Diptera: Chloropidae), with Synonymy of Incertella Sabrosky, Zootaxa 5481 (4), pp. 401-439 : 408-409

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.

Figures

FIGURES 1–8. Microcercis morphology. 1, M. infesta scutal tomentum and setae, 1500X. 2, M. infesta anterior margin of frons, antennal bases, and dorsal portion of carina, 1500X. 3, M. infesta lower face and frontoclypeal membrane, 800X. 4, M. trifeminarum eye, showing density and length of ommatrichia, 1500X. 5, M. infesta frontal and vertical chaetotaxy, 400X. 6, M. trifeminarum scutellum and subscutellum (arrow), 1000X. 7, M. bispina scapular setae (arrows), 400X. 8, M. species proepimeral seta (arrow), 1000X.

FIGURES 15–22. Microcercis morphology. 15, M. albipalpis habitus, lateral view. 16, M. bispina habitus, lateral view. 17, M. dorsata habitus, lateral view. 18, M. infesta habitus, lateral view. 19, M. insularis habitus, lateral view. 20, M. minor habitus, lateral view. 21, M. johanni habitus, lateral view. 22, M. murphyi habitus, lateral view.

FIGURES 23–30. Microcercis and Conioscinella morphology. 23, M. laytoni habitus, lateral view. 24, M.trifeminarum habitus, lateral view. 25, C. ovalis HOLOTYPE habitus, lateral view. 26, M. albipalpis male genitalia, posterior oblique view. 27, M. albipalpis surstylus. 28 M. bispina male genitalia, posterior oblique view. 29, M. dorsata male genitalia, posterior oblique view. 30, M. infesta male genitalia, posterior oblique view.