Mesembrinella longicercus Whitworth, 2019

Whitworth, Terry L. & Yusseff-Vanegas, Sohath, 2019, A revision of the genera and species of the Neotropical family Mesembrinellidae (Diptera: Oestroidea), Zootaxa 4659 (1), pp. 1-146 : 125-126

publication ID 10.11646/zootaxa.4659.1.1

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Mesembrinella longicercus Whitworth

sp. nov.

Mesembrinella longicercus Whitworth , sp. nov.

( Figs 77–78 View FIGURES 75–80 , 167–168 View FIGURES 163–172 , 226 View FIGURES 222–228 , 269 View FIGURES 266–279 , 313 View FIGURES 312–317 , 357 View FIGURES 350–369 , 398 View FIGURES 370–400 , 442 View FIGURES 439–453 , 476 View FIGURES 474–478 , 488 View FIGURE 488 )

Diagnosis. A small blue-black fly averaging 9.3 mm (9–10/3) in length; ppn 3x 3; stem vein bare; wing hyaline; ppn and pleura bluish; T5 with long, slender, dense setae in both sexes. Male frons narrow, 0.04 of head width at narrowest; terminalia with cercus much longer than surstylus ( Figs 77–78 View FIGURES 75–80 ); phallus in dorsal view exceptionally narrow ( Fig. 168 View FIGURES 163–172 ). Female terminalia as in Fig. 313 View FIGURES 312–317 .

Description. Male. Head. Frons 0.043 (0.035 –0.050 /2) of head width at narrowest, about twice width of anterior ocellus; fronto-orbital moderately broad, orange, with golden tomentum, frontal setae ascending about halfway to vertex; frontal vitta orange, broad below, obliterated midway above; parafacial orange, upper half with yellow pubescence, lower half bare; anterior 2/3 of gena orange, posterior 1/3 dark silvery; stout row of black setae extending horizontally across gena; postgena dark silvery with silky, golden setae; occiput with silvery tomentum and golden setae, cuticle shiny black below and behind edge of postoccipital row; median occipital sclerite shiny black; palpus typical; antenna orange except tip of arista dark brown; eye with median facets about 2x size of lateral facets; ocellar triangle medium-sized, anterior ocellus slightly larger than posterior ocelli; supravibrissal setae black and ascending about 1/5 of distance to antennal base.

Thorax. Dorsum and pleural area blue-black with weak pale tomentum; chaetotaxy: ac 2:1, dc 2:3, ia 0, ph 1 ppn 3x 3, kat 2:1; meron with vertical row of stout black setae, horizontal section composed of only 1–2 setae, 1 pair converging ap, 1 weak sa, 1 lat; 1 stout bas, 1 pb, 1 disc; subscutellum moderately developed; spiracles moderate in size, brown; legs entirely dark brown except apices of femora orange. Wing hyaline except veins in base of wing darkened; subcostal sclerite with heavy pubescence; tegula and basicosta dark brown; section IV 0.24 of section III; disc of upper calypter tan, rim dark with short dark setae; disc and rim of lower calypter dark brown, rim with long dark setae.

Abdomen. T1+2–4 shiny blue with thin tomentum, T5 with heavier tomentum. T4 with stout posterior row of erect, black setae; disc of T5 with sparse, long, fine setae. Terminalia distinctive, in left lateral view surstylus long and straight, cercus even longer and also straight ( Fig. 77 View FIGURES 75–80 ); in posterior view, surstylus much shorter than cercus, curved outward at tip, cerci broader at base, moderately narrowing to tips ( Fig. 78 View FIGURES 75–80 ); phallus in lateral view with epiphallus slender and only slightly curved backward ( Fig. 167 View FIGURES 163–172 ); in dorsal view, phallus very narrow, much narrower than in other species of this group, basiphallus with wing-like expansions ( Fig. 168 View FIGURES 163–172 ). T6, STS7+8, pre- and postgonite, ejaculatory sclerite and ST6 as in Fig. 226 View FIGURES 222–228 ; ST1–5 broad, as in Fig. 269 View FIGURES 266–279 .

Female [a single specimen]. Similar to male except frons 0.23 of head width at narrowest. T6 of OV shape; T7 narrowed midway with suture; T8 as two broad sclerites nearly touching midway ( Fig. 313 View FIGURES 312–317 ); ST6–8 and hypoproct as in Fig. 357 View FIGURES 350–369 ; spermathecae filiform ( Fig. 398 View FIGURES 370–400 ); ST1–5 as in Fig. 442 View FIGURES 439–453 .

Type material. HOLOTYPE ♂♦* ( TLW299 ) ( Bolivia , La Paz ; USNM; Fig. 476 View FIGURES 474–478 ), labeled: BOLIVIA: Depto. La Paz / 8 km S. Chulumani, Apa Apa / ex: malaise trap, 1950–2100 m / 16°22ʹS 67°30.4ʹW / 24 - iii - 2001, S.D. Gaimari GoogleMaps ; HOLOTYPE / Mesembrinella / longicercus / T.L. Whitworth.

ALLOTYPE ♀ ♦* ( TLW300 ): same data as holotype except 23.iii.2001 ( USNM). GoogleMaps

PARATYPE: Bolivia, La Paz. 1 ♂♦* ( TLW298 ) , Coroico, Cerro Uchumachi, 16°12ʹ43ʺS 67°42ʹ49ʺW, 2550 m, 16.iv.2001, cloud forest, S.A. Marshall ( UGG) GoogleMaps . Chapare. 1 ♀, Chochabamba, 1100 m, iii.1962, F.H. Walz ( CNC) .

Distribution. Bolivia.

Remarks. Three specimens ( TLW 298–300) were barcoded; they clustered together close to M. decrepita ( Fig. 488 View FIGURE 488 ). This species also has a long, straight surstylus like most species in the M. aeneiventris group. However, the lack of a row of well defined, stout setae on the disc of T5 led us to conclude it should be placed in the M. bicolor group. Like M. bullata sp. nov., this species needs further study for a better definition of its taxonomic position.

Etymology. The name longicercus is derived from the Latin longus (meaning long) and cercus, and refers to the exceptionally long male cerci of the species.


Smithsonian Institution, National Museum of Natural History


University of Guam


Canadian National Collection of Insects, Arachnids, and Nematodes













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