Microcercis dorsata (Loew), 2024

Foster, George A., 2024, Revision of Nearctic Microcercis Beschovski (Diptera: Chloropidae), with Synonymy of Incertella Sabrosky, Zootaxa 5481 (4), pp. 401-439 : 409-410

Microcercis dorsata (Loew)

( Fig. 17 , 29 )

Oscinis dorsalis Loew, 1869: 43 . (Cent. VIII, no. 77). Preoccupied name. Type locality: Rhode Island. Deposited Museum of Comparative Zoology ( MCZ), Harvard University, Cambridge, Massachusetts .

Oscinis dorsata Loew, 1872: 115 . (Cent. X, appendix, incorrectly cited by Loew as “ Cent. IX, no. 77”) [Change of name]. Type locality: Newport, Rhode Island. Deposited MCZ. NEW COMBINATION .

Botanobia spiniger Malloch, 1918: 109 . Type locality: Urbana Illinois, Augerville Woods. Deposited INHS.

Oscinella spiniger .— Sabrosky 1935: 258, 264, 267; Sabrosky 1936: 722 723 [Synonym of dorsata ].

Incertella dorsata . — Sabrosky 1980: 421 [new comb. with Incertella ]

Diagnosis.—Ocellar triangle mostly gray with posterior corners yellow to mostly yellow with ocellar tubercle black or gray tomentose on tubercle and slightly towards apex; vertex yellow; occiput gray to black tomentose; postpedicel usually brown dorsally, yellow ventrally but rarely nearly all brown; prosternum brown; one pair of strong, black, scapular setae between postpronotal lobes; scutum gray; postpronotal lobe and notopleuron often light yellow; pleuron varies from brown with yellow areas to mostly orange; ventral polished area continuous from propleuron to meron; 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 small triangulate to quadrate lobes; surstylus short, parallel sided, distal margin smooth, rounded, dorsal tip angulate.

Description.—Body length; female: 1.28−1.96 mm; male: 1.04−1.80 mm.

Head: Ocellar triangle mostly gray with posterior corners yellow to mostly yellow with ocellar tubercle black or gray tomentose on tubercle and slightly towards apex; vertex yellow to dark gray; occiput brown to black tomentose either entirely or mainly in center behind head; frons yellow; scape and pedicel yellow, postpedicel dorsal two−thirds black, ventral third yellow, sometimes mostly black with a narrow band of yellow along ventral margin; arista black, pubescent; face, palps, gena, and clypeus yellow; prementum polished brown, labellum yellow, occasionally brown; gena to eye ratio 0.23.

Cephalic chaetotaxy: Fronto-orbital setae yellow; interfrontal setae yellow; ocellar setae orange yellow; postocellar setae orange yellow to black; outer vertical setae orange to black; inner vertical setae orange to black; postocular setae mostly yellow, postocular region often with one strong black postocular seta at about the dorsal third of the occiput; vibrissae yellow; subgenal setae yellow.

Thorax: Prosternum bright yellow; prescutum polished black; scutum tomentose, may be entirely gray to black or with two broad yellow areas anteriorly, or grayish yellow on the anterior half and light gray on posterior half; postpronotal lobe and notopleuron yellow; pleuron may be entirely yellow or with the following color and tomentum pattern: mostly yellow except dark brown along the anterior margin of the anepisternum, the anterior margin of the anepimeron, the anterior ventral portion of the katepisternum, the katatergite, most of the meron just above the hind coxa; anepisternum and anepimeron lightly tomentose, remainder of pleuron polished; mediotergite mostly polished black, gray tomentose on lateral areas; scutellum can be entirely yellow or light gray or yellow only at posterior tip when viewed from posterior, entirely tomentose; subscutellum light gray to yellow tomentose; wing length 1.36–1.98 mm, hyaline, costal ratios 0.54:0.34:0.19; fore and hind coxa yellow, mid coxa light brown or yellow; all femora yellow, except mid femur mostly yellow with a brown spot on central posterior surface; fore and mid tibia yellow, hind tibia dark centrally; tarsomeres 1−3 dark yellow to light yellow, tarsomeres 4−5 dark; femoral organ not imaged; tibial organ brown or yellow.

Thoracic chaetotaxy: One pair strong, black, scapular setae; scutum and scutellum with yellow setae and setulae.

Abdomen: Syntergite 1+2 brown centrally, yellow laterally; remaining tergites brown with narrow yellow posterior margins. Male terminalia (fig. 29): epandrium brown tomentose with many setulae; cerci small triangulate to quadrate lobes; surstylus short, parallel sided, distal margin smooth, rounded, dorsal tip angulate. Female cerci and terminalia black.

Distribution.—Nearctic: Canada (Prince Edward Island). United States (Connecticut, Indiana, Iowa, Kansas, Kentucky, Maine, Maryland, Massachusetts, Michigan, New Hampshire, New York, Missouri, North Carolina, North Dakota, South Dakota, Vermont, Virginia).

Discussion.—This species is distinguished from most other Nearctic Microcercis species by the overall yellow ground color of the body and a pair of strong, black scapular setae on each side of the anterior scutum between the postpronotal lobes, a character shared with M. bispina . The colors of the pleuron can be quite variable in depth, when in doubt the presence of the strong, black scapular setae confirm the identity of M. dorsata . It also, very often, has one strong, black postocular seta about a third of the way ventrad from the vertex.

Figures

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.