Mesembrinella uniseta Aldrich, 1925

(Figs 49–50, 139–140, 212, 255, 298, 342, 384, 427, 467, 488)

Mesembrinella uniseta Aldrich, 1925: 13 . Holotype male (USNM), examined. Type locality: La Suiza de Turrialba, Costa Rica.

Huascaromusca uniseta: Hall (1948: 84, transferred to Huascaromusca); Kosmann et al. (2013: 77); Wolff et al. (2017: 253); Marinho et al. (2017: tab. 1).

Mesembrinella uniseta: Cerretti et al. (2017: tab. 2).

Diagnosis. A medium-sized blue-black fly averaging 9.8 mm (9–10/5) in length. Postpronotal lobe with 3x 3 setae; subcostal sclerite bare; femora dark; anterior thoracic spiracle pale. Male frons exceptionally wide, about 0.14 of head width at narrowest.

Redescription. Male. Head. Frons broad, 0.136 (0.13–0.15/5) of head width at narrowest. Fronto-orbital, frontal vitta and parafacial pale yellow-gold when viewed from above, orange when viewed from below; frontoorbital with row of setae ascending about 2/3 up frons, ending with a few weak setae below ocellar triangle; lower 1/4 frontal vitta orange, the rest black; gena with horizontal row of stout black setae extending from postgena across to lower parafacial; postgena dark with silvery tomentum, anterodorsal edge with dark setae, remainder with long silky yellow setae; palpus typical; antenna, pedicel and first flagellomere orange, base of arista orange, remainder brown; occiput blue with pale tomentum; upper 1/3 of occiput with short dark setae, lower 2/3 with pale setae; median occipital sclerite shiny, upper edge bluish, remainder black; eye with facets uniform in size; ocellar triangle medium-sized; anterior ocellus slightly larger than posterior ocelli; facial ridge with small cluster of black supravibrissal setae at base.

Thorax. Dorsum and pleura dark blue with whitish tomentose stripes and a pair of polished areas dorsolaterally in presutural area; chaetotaxy: ac 2:1, dc 2:3, ia 0, ph 1, ppn 3x 3, kat, 2:1, meron with long slender black setae, 1 pair converging ap, sa absent, sometimes 1 weak lat, 1 stout bas, 1 weak pb, 1 disc; subscutellum prominently developed; anterior spiracle pale yellow, posterior spiracle darker orange; legs brown except small orange area at joint of femora and tibiae. Wing hyaline; section IV 0.10 of section III; disc of upper calypter tan, rim dark with long tan setae; disc of lower calypter tan, rim tan with long pale setae; subcostal sclerite tan with pubescence only; basicosta yellow-brown, tegula dark brown.

Abdomen blue with whitish tomentum, with pair of stout setae on lateral margins of T1–5; row of stout setae on posterior margins of T4–5, disc of T5 with row of stout setae midway, rest of disc with sparse, fine setae. Terminalia in lateral view with surstylus narrow at base, expanded midway and narrower at tip (Fig. 49); in posterior view, cerci short and broad, unlike in other species of the genus (Fig. 50); phallus in lateral view as in Fig. 139; in dorsal view, hypophallic lobes very narrow (Fig. 140); T6, STS7+8, pre- and postgonite, ejaculatory sclerite, ST6 and hypandrium as in Fig. 212; ST1–5 as in Fig. 255.

Female. Similar to male except frons 0.246 (0.23–0.26/5) of head width at narrowest. T6 of OU shape; T7 continuous, narrowed midway; T8 as two widely separated sclerites; epiproct bilobed (Fig. 298); ST6–8 and hypoproct as in Fig. 342; spermathecae filiform (Fig. 384); ST2–5 as in Fig. 427.

Type material examined. HOLOTYPE ♂ ( Costa Rica, Cartago; USNM; Fig. 467), labeled: COSTA RICA / La Suiza ’23 [= 1923] / Pab. Schild; 29 III [probably 29 March]; Mesembrinella / uniseta / Ald.; AL Melander / Collection / 1961; Type / 26798 / No. / U.S. N.M. [red label]; USNMENT01288287.

Remarks. Aldrich (1925) stated that the number was 26797 but the specimen label on the type says 26798.

PARATYPES: Costa Rica, Cartago. 1 ♂, 1 ♀ [both labeled “ paratype #26798”], La Suiza, 29.iii.1923, Pablo Schild (USNM); 1 ♂, 1 ♀ [both labeled “ paratype #26798”], same data as previous (NHMUK) .

Additional material examined. Costa Rica, Cartago. 1 ♂*, 1 ♂♦ (TLW408), 1 ♀ *, 1 ♀, R. Grande de Orosi desde Administracion hasta Send. La Pava, 1150–1600 m, ii.1997, R. Guzmán (INBIO) ; 1 ♂, 1 ♀, R. Grande de Orosi, desde Administración hasta Send. La Pava, 1150–1600 m, ii.1997, L_N_192500 560400 #45463, R. Guzmán (INBIO) ; 1 ♂♦ (TLW404), 1 ♂♦* (TLW405, terminalia glued on pin), 1 ♂, 1 ♀ *, Tapanti, Quebrada Segunda, Orilla del Rio Grande de Orosi, 1–150 m, 18–20.ii.1997, L_N_192500 560401 #45297, M. Segura (IN- BIO) .

Distribution. Costa Rica.

Remarks. Hall (1948) moved M. uniseta to Huascaromusca . Three specimens (TLW 404–405 and TLW 408) were barcoded; the sequences clustered together close to M. bullata (Fig. 488).