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

Macrostomus falcatus sp. nov.

( Figs 10 A–M)

urn:lsid:zoobank.org:act:2467BB72-7161-4756-8CDF-4C6A254D0D34

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 ). 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 ) 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 ) shiny brown (specimen from alcohol). Tergites 1–3 with slightly longer setae posteriorly. Paratype ♂: Tergite 8 ( Fig. 10C ) subrectangular, with posterior margin desclerotized, without distal sinus; base with shallow sinus. Sternite 8 ( Fig. 10D ) without posterolateral saddle-shaped projection. Tergite 8 and sternite 8 ( Fig. 10E ) narrowly articulated. Epandrium ( Fig. 10F ) 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 ) somewhat small, well sclerotized, with mesial setae; mesial branch ( Fig. 10H ) forming small L-shaped cercal bridge when viewed laterally; mesial connection of cercal bridge rounded ( Fig. 10I , outlined) when viewed posteriorly. Median cercus ( Fig. 10H ) semi globose, upwardly directed with longer setae anterodorsally. Posterior cercus ( Figs 10G, H ) wider basally, upwardly directed, simple, acuminate distally, placed in parallel to posterior lobe of epandrium. Ventral projection of cercus ( Fig. 10I ) flat, fused medially, bilobate dorsally, with inconspicuous ventral lobe with 2 small setae. Dorsal hypoproctal lobe ( Fig. 10J ) bigger than ventral lobe of hypoproct, both distinctly setose. Hypandrium ( Figs 10K, L ) slightly wider distally, bifid and membranous distally. Ejaculatory apodeme ( Fig. 10K ) 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 ) ( 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.

Figures

FIGURE 10. Macrostomus falcatus sp. nov. A–B, holotype ♂, C–L paratype ♂ from La Paz, Zongo. A. Habitus, lateral view; B. Apex of abdomen, lateral view; C. Tergite 8, dorsal view; D. Sternite 8, ventral view; E. Tergite and sternite 8, lateral view; F. Epandrium, detached, lateral view (longer setae broken); G. Terminalia (epandrium, hypandrium and phallus removed), lateral view; H. Terminalia, posterior view; I. Cercal bridge of anterior cercus (outlined) and ventral projection of cercus, anterior view; J. Anterior cercus, dorsal view (cercal bridge outlined); K. Hypandrium, ejaculatory apodeme and phallus, lateral view; L. Hypandrium, posterior view (alveoli highlighted); M. Holotype labels. Scale bars, figure A = 1 mm; B–L = 0.2 mm. Abbreviation: crbd, cercal bridge; vpc, ventral projection of cercus.