Macrostomus montanus, 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 : 259-261

Macrostomus montanus sp. nov.

( Figs 6 A–N, 7A–E)

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Diagnosis. Gena and postgena with setae somewhat stout; wing almost entirely hyaline, slightly brown infuscate at apex of costal cell, pterostigma and apex of cell r 2+3; last section of vein M 4 longer than vein dm-m; cell dm somewhat acute; tergite 8 short with distal sinus; epandrium with posterodorsal lobe longer than anterodorsal lobe, with longer setae more concentrated posteriorly on posterodorsal lobe; posterior cercus inwardly curved, trifid, apparently glabrous; hypandrium well sclerotized, slightly wider medially at level of posterior longer setae.

Description. Holotype ♂ ( Fig. 6A ). Body length 3.5 mm; wing length 3.2 mm. Head dichoptic. Frons shiny black, slightly wider than anterior ocellus width. Two pairs of proclinate ocellar setae, posterior pair weaker. Face narrower than frons width, same as anterior ocellus width. Postcranium shiny black, entirely and sparsely gray pruinose. Inner vertical seta stouter than outer vertical seta, latter subequal in length to uniseriate postocular row of setae; 2–3 pairs of dorsal occipital setae. Gena with 3 setae and postgena with 2 somewhat stout setae. Antenna velvety black with postpedicel short pubescent. Proboscis shiny, brown basally, yellow apically. Palpus black. Thorax shiny black, gray pruinose. Thoracic chaetotaxy: 4 antepronotals; 1 postpronotal stout and 2 minutes; 4 dorsocentrals (right row with 5); 1 presutural supra-alar; 1 postsutural supra-alar; 1 postalar stout, 1 minute; 4 proepisternals weak; 1 notopleural stout and 1 weak; 2 pairs of scutellars, outer pair slightly weaker; 7 laterotergitals. Legs yellow with distal 3/4 of fore tibia, apex of mid femur, entire mid tibia, distal half of hind femur, entire hind tibia, all tarsi brown to black. Legs longer setae: fore tibia with 1 sub-basal and 1 median anterodorsal slightly longer; mid femur with 1 subapical anterior slightly longer; mid tibia with alternating anterodorsal and posterodorsal equally spaced; hind femur with 1 anterior subapical; hind tibia ( Fig. 6A ) with 4–5 slender dorsal and hind tarsomere 1 with 1 longer median dorsal seta. Wing ( Fig. 6A ) almost entirely hyaline, slightly brown infuscate at apex of costal cell, pterostigma and apex of cell r 2+3. Veins M 1 and M 2 weaker and apex of CuA+CuP evanescent. Last section of vein M 4 longer than vein dm-m. Cell dm somewhat acute. Halter light yellow. Abdomen ( Fig. 6B ) shiny black; tergites 1–3 with longer setae posteriorly. Tergite 8 ( Fig. 6C ) with distal sinus. Sternite 8 ( Fig. 6D ) with distinct saddle-shaped projection posterodorsally and deep basal sinus. Tergite 8 articulated with sternite 8 somewhat horizontally ( Fig. 6E ). Epandrium ( Fig. 6F ) with posterodorsal lobe longer than anterodorsal lobe, with longer setae more concentrated posteriorly on posterodorsal lobe; anterodorsal cleft minute, inconspicuous (smaller seta on Fig. 6F ); anteroventral cleft distinct (stronger seta on Fig. 6F ). Anterior cercus ( Figs 6G, J ) small in lateral view, well sclerotized, with longer setae dorsally and posteriorly; when viewed anteriorly ( Fig. 6H ) emitting mesially large and flat cercal bridge connected medially; cercal bridge expanded posteriorly and fused with upper hypoproctal lobe when viewed dorsally ( Fig. 6I ). Median cercus ( Fig. 6J ) somewhat cup-shaped with longer setae dorsally. Posterior cercus ( Fig. 6J ) inwardly curved, trifid, apparently glabrous. Ventral projection of cercus ( Fig. 6K ) horizontally placed, distally expanded and setose. Dorsal lobe of hypoproct somewhat inconspicuous, fused with cercal bridge expansion of anterior cercus; ventral lobe of hypoproct distinctly setose, placed between setose lobes of ventral projection of cercus and cercal bridge of anterior cercus. Hypandrium ( Figs 6L, M ) well sclerotized, almost same width throughout, slightly wider medially at level of posterior longer setae; distally with two pairs of curved hooks, distal pair stouter. Ejaculatory apodeme ( Fig. 6L ) tetralamellar, all lamella subequal. Phallus ( Fig. 6L ) slightly longer than hypandrium.

Female. Frons wider than width of anterior ocellus, wider than in male. Face slightly narrower than frons, approximately as wide as width of anterior ocellus. Wing distinctly more infuscated at costal and distal margins ( Fig. 7A ). Tergite 8 ( Figs 7B, C ) wider basally in lateral view; with shallow basal sinus and deep distal sinus in dorsal view. Sternite 8 ( Figs 7B, D, E ) highly modified; in lateral and ventral views widened distally and with ventral subapical small translucid protuberance. Genital fork ( Figs 7D, E ) T-shaped with arms upwardly directed. Genital chamber ( Fig. 7D, E ) well sclerotized, wide, U-shaped, with basal protuberance upwardly directed.

Geographical records. Bolivia (La Paz).

Type material examined. HOLOTYPE ♂, paratype ♀, on same pin: “ BOLIVIA, La Paz, Chulumani, cloud forest, above 2000 m [eters]”; “ In copula, Chulumani , 5.iv. [19]79”; “QR code: NHMUK 010664427 ”; “Holot ♂ Parat ♀ Macrostomus montanus Rafael & Marques ” ( Fig. 6N ) (NHMUK). PARATYPES: Bolivia : same data as holotype, except 2.iv. [19]79, QR code : NHMUK 0 10864440 (1♂, NHMUK) ; NHMUK 0 10664353 (1♀, INPA) ; NHMUK 0 10664429 (1♀, NHMUK) ; NHMUK 0 10664436 (1♀, NHMUK) ; NHMUK 0 10664441 (1♀, NHMUK) ; NHMUK 0 10664442 (1♀, INPA); same data, except 25.iii. [19]79 , NHMUK 0 10664430 (1♀, NHMUK, dissected) ; La Paz, Sarampionim [sic], 23.ii.2005, Arm. Malaise, J. Rodriguez (1♀, CBF) .

Holotype condition. Good. Left hind leg lost; right hind leg glued on piece of white card; abdomen not dissected.

Etymology. From the Latin montanus = mountain and refers to the high elevation where the specimens were collected.

Variation. One specimen (QR code: NHMUK 010864440) with three pairs of ocellar setae; the additional anterior pair slightly longer than posterior pair.

Remarks. Macrostomus montanus sp. nov. is tentatively included in the M. limbipennis species-group, however, it differs mainly by having epandrium with posterodorsal lobe longer than the anterodorsal lobe. In the key presented by Rafael & Cumming (2012), this species runs to couplet 3 separating M. limbipennis (Bezzi) from M. penai Rafael & Cumming , but it differs from the first species by male tergite 8 not humped and from the second species by all cercal lobes shortened (versus elongate and upwardly directed in M. penai ), posterior lobe of epandrium longer than anterior lobe (versus same length) and by female sternite 8 with a ventral subapical small translucid protuberance (versus absent), genital fork T-shaped with arms upwardly directed (versus small rod, without lateral arms), genital chamber wide, U-shaped, well sclerotized (versus membranous).

Figures

FIGURE 6. Macrostomus montanus sp. nov. paratype ♂. A. Habitus, before abdomen dissected, lateral view; B. Abdomen, dorsal view; C. Tergite 8, dorsal view; D. Sternite 8, ventral view; E. Tergite and sternite 8, lateral view; F. Epandrium detached, lateral view (superior arrow indicating anterodorsal cleft, inferior arrow indicating anteroventral cleft); G. Epandrium and cerci, lateral view (pieces outlined); H. Cercal bridge of anterior cercus and subepandrial sclerite, anterior view; I. Cercal bridge of anterior cercus, dorsal view; J. Anterior, median and posterior lobes of cerci, lateral view; K. Dorsal and ventral hypoproctal lobes, posterior view; L. Hypandrium, ejaculatory apodeme and phallus, lateral view; M. Hypandrium, posterior view; N. Holotype labels. Scale bars, figures A–B = 1 mm; C–M = 0.2 mm. Abbreviations: ACe, anterior cercus; ADL, anterodorsal lobe of epandrium; cbrd, cercal bridge; DHyL, dorsal hypoproctal lobe; Ej Apod, ejaculatory apodeme; Hypd, hypandrium; MCe, median cercus; PCe, posterior cercus; PDL, posterodorsal lobe of epandrium; Ph, phallus; sbep scl, subepandrial sclerite; St, sternite; Tg, tergite, VHyL, Ventral hypoproctal lobe.

FIGURE 7. Macrostomus montanus sp. nov. paratype ♀, A. Habitus, lateral view (specimen from Sarampioni, CBF collection); B–E. Specimen from Chulumani, NHMUK 010864430. B. Apex of abdomen, lateral view; C. Apex of abdomen, dorsal view; D. Sternite 8, genital fork and genital chamber, lateral view; E. Sternite 8 with genital fork and genital chamber placed laterally. Scale bars, figure A = 1 mm; figures B–E = 0.2 mm. Abbreviations: Ce, cercus; GC, genital chamber; GF, genital fork; St, sternite; Tg, tergite.