Macrostomus falcatus, Rafael & Marques, 2019

Rafael, José Albertino & Marques, Dayse Willkenia Almeida, 2019, Five new species of Macrostomus Wiedemann and a checklist of Empididae (s. str.) (Diptera) from Bolivia, Zootaxa 4567 (2), pp. 251-275: 264-266

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Macrostomus falcatus

sp. nov.

Macrostomus falcatus   sp. nov.

( Figs 10 View FIGURE 10 A–M)

Diagnosis. Postcranium with upper postocular third shiny with no pruinescence. Wing hyaline, slightly brown infuscation at pterostigma and apex of cell r 2+3. Tergite 8 subrectangular, with posterior margin desclerotized. Epandrium with posterodorsal lobe much longer than anterodorsal lobe, sickle-shaped. Anterior cercus, when viewed laterally, with mesial branch forming a small L-shaped cercal bridge. Posterior cercus sickle-shaped, upwardly directed, placed parallel to posterior lobe of epandrium.

Description. Holotype ♂ ( Fig. 10A View FIGURE 10 ). Body length 3.0 mm; wing length 3.0 mm. Head dichoptic. Frons shiny brown, slightly wider than width of anterior ocellus. One pair of proclinate ocellar setae. Face narrower than frons, slightly wider ventrally. Postcranium shiny brown, sparsely gray pruinose, except upper postocular third shiny without pruinescence. Inner vertical seta stouter than outer vertical seta, latter subequal in length to uniseriate postocular row of setae; 2 pairs of dorsal occipital setae. Gena with 2 small setae and postgena with 1–2 minute setae. Antenna velvety black with postpedicel short setulose. Proboscis mainly shiny yellow. Palpus brown to black. Thorax shiny brown to black, more distinctly brown pruinose on disc of scutum, scutellum and mediotergite. Postpronotal lobe slightly yellow. Thoracic chaetotaxy: 3 antepronotals small; 1 postpronotal stout, 1 weak; 4 dorsocentrals; 1 presutural supra-alar; 0 postsutural supra-alar; 1 postalar; 2 minute proepisternals; 2 notopleurals, posterior stouter; 2 pairs of scutellars, outer pair weaker; 4 laterotergitals. Legs shiny yellow with distal 1/5 of hind femur, entire hind tibia and tarsus light brown to black. Legs longer setae: hind femur with 1 anteroventral seta at base of distal fourth; hind tibia with 4 slender dorsal setae; hind tarsomere 1 with 1 median slender dorsal seta. Wing ( Fig. 10A View FIGURE 10 ) hyaline, slightly brown infuscate at pterostigma and apex of cell r 2+3. Veins M 1, M 2 and CuA+CuP entirely evanescent. Last section of vein M 4 longer than dm-m. Cell dm short and slightly projected. Halter whitish. Abdomen ( Figs 10A, B View FIGURE 10 ) shiny brown (specimen from alcohol). Tergites 1–3 with slightly longer setae posteriorly. Paratype ♂: Tergite 8 ( Fig. 10C View FIGURE 10 ) subrectangular, with posterior margin desclerotized, without distal sinus; base with shallow sinus. Sternite 8 ( Fig. 10D View FIGURE 10 ) without posterolateral saddle-shaped projection. Tergite 8 and sternite 8 ( Fig. 10E View FIGURE 10 ) narrowly articulated. Epandrium ( Fig. 10F View FIGURE 10 ) with posterodorsal lobe much longer than anterodorsal lobe, with small mid projection anteriorly; without anterodorsal cleft and anteroventral cleft as inconspicuous unsclerotized area; with longer setae posteriorly (setae broken in figure). Anterior cercus ( Figs 10G, H View FIGURE 10 ) somewhat small, well sclerotized, with mesial setae; mesial branch ( Fig. 10H View FIGURE 10 ) forming small L-shaped cercal bridge when viewed laterally; mesial connection of cercal bridge rounded ( Fig. 10I View FIGURE 10 , outlined) when viewed posteriorly. Median cercus ( Fig. 10H View FIGURE 10 ) semi globose, upwardly directed with longer setae anterodorsally. Posterior cercus ( Figs 10G, H View FIGURE 10 ) wider basally, upwardly directed, simple, acuminate distally, placed in parallel to posterior lobe of epandrium. Ventral projection of cercus ( Fig. 10I View FIGURE 10 ) flat, fused medially, bilobate dorsally, with inconspicuous ventral lobe with 2 small setae. Dorsal hypoproctal lobe ( Fig. 10J View FIGURE 10 ) bigger than ventral lobe of hypoproct, both distinctly setose. Hypandrium ( Figs 10K, L View FIGURE 10 ) slightly wider distally, bifid and membranous distally. Ejaculatory apodeme ( Fig. 10K View FIGURE 10 ) with dorsal lamella very short. Phallus slightly longer than hypandrium.

Female. Unknown.

Geographical records. Bolivia (La Paz and Cochabamba)   .

Type material examined. HOLOTYPE ♂: “ BOLIVIA, La Paz, Sarampionim [sic], 23.ii.2005, Arm.[adilha] Malaise, J. Rodriguez ”; “ Holotype ♂ Macrostomus falcatus Rafael & Marques   ” ( Fig. 10M View FIGURE 10 ) ( CBF)   . PARATYPES: Bolivia: La Paz, Zongo, 30.i.2005, Arm. Malaise, J. Rodriguez (1♂, INPA, dissected); Cochabamba, Villa Tunari , 300 m, 20.x.1981, M. Cooper, QR code: NHMUK   0 10864408 (1♂, NHMUK)   .

Holotype condition. Good, pinned.

Etymology. From the Latin falcatus   = sickle-shaped, which refers to the shape of the posterior lobe of epandrium and the posterior cercus.

Variation. Specimen from alcohol distinctly paler (brown) than specimen without alcohol preservation (black).

Remarks. Macrostomus falcatus   sp. nov. appears closely related to M. albicaudatus Rafael & Cumming   and M. trombetensis Rafael & Cumming   based on a similar epandrium with the posterodorsal lobe longer than the anterodorsal lobe and posterior cercus elongate, upwardly directed and somewhat simple. It differs from both species by the posterior cercus without protuberances (versus with protuberances or setae), apex of hypandrium with an apical projection somewhat membranous, bifid when viewed posteriorly (versus absent). In the key presented by Rafael & Cumming (2015), this species runs to couplet 5 separating M. amazonensis Rafael & Cumming   from M. paraiba Rafael & Cumming   , but the posterior lobe of the epandrium is shorter in both these species, while it is longer in M. falcatus   sp. nov.


Coleccion Boliviana de Fauna


Instituto Nacional de Pesquisas da Amazonia


Natural History Museum, London