Macrostomus, Wiedemann, 1817

Rafael, José Albertino & Vasconcelos, Manuela Santos, 2024, A new species-group of Macrostomus (Diptera, Empididae) with notable spotted wings recorded from the North Amazonia biogeographical component and a key to species-groups, Zootaxa 5433 (3), pp. 429-438 : 435-436

Key to Macrostomus species-groups based mainly in male specimens

1 Male and female wings dark with distinct fenestrate hyaline spots ( Figs 1B , 2B , 3B , 4B ); veins R 2 +3 and R 4 +5 curved, converging to each other, leaving cell r 2+3 narrowed subapically. Female. Legs with mid femur, hind femur, and hind tibia with dorsal and ventral pennate scales ( Fig. 4A ).................................................... M. megatarsus species-group

- Male and female specimens with different pattern of infuscation; veins R 2+3 and R 4+5 not converging to each other. Female. Legs sometimes as above, or with variable dorsal and ventral pennate scales on hind leg or without pennate scales............. 2

2 Male wings distinctly brown infuscate on costal and distal margins, on crossvein r-m, and slightly on crossvein dm-m ( Rafael & Cumming 2010, figs 1A, 2A). Female wings distinctly more infuscated on respective regions of males ( Rafael & Cumming 2010, figs 1G, 2E). Female legs with pennate scales on flattened hind femur, hind tibia and often on mid femur ( Rafael & Cumming 2010, figs 1E, F, 4D, E), rarely on mid tibia.................................. M. pictipennis species-group

- Male and females wings infuscated on costal and distal margins to almost entirely hyaline ( Rafael & Cumming 2009, fig. 2A, F; Rafael & Cumming 2015, figs 54–63); pterostigma slightly darker. Female legs with pennate scales only on hind tibia dorsally, sometimes present ventrally or hind tibia without pennate scales................................................ 3

3 Male tergite 8 with posteromedial projection, with apex acute ( Rafael & Cumming 2009, figs 1B, 2B, 3B), or apex blunt ( Rafael & Cumming 2009, figs 4B, 6B) or apex bifid ( Rafael & Cumming 2009, fig. 5B)................................... 5

- Male tergite 8 without posteromedial projection beyond posterior margin ( Rafael & Cumming 2012, figs 5, 29, 36) or with two posterolateral protuberances apically ( Rafael & Cumming 2012, fig. 17).......................................... 4

4 No supra-alar postsutural setae; 1–2 pairs of scutellar setae. Cell dm somewhat blunt posteriorly ( Rafael & Cumming 2015, figs 54–63). Hypandrium generally narrowed on distal third of posterior margin ( Rafael & Cumming 2015, figs 14, 22, 33) or notched, with small sinus on distal third ( Rafael & Cumming 2015, fig. 5)................. M. amazonensis species-group

- One supra-alar postsutural seta; 2 pairs of scutellar setae. Cell dm slightly projected posteriorly ( Rafael & Cumming 2012, figs 4, 15, 16, 20, 27). Hypandrium somewhat same diameter along entire length ( Rafael & Cumming 2012, figs 7, 19) or distinctly widened on distal half ( Rafael & Cumming 2012, figs 31, 38)............................ M. limbipennis species-group

5 Hypandrium generally slender, narrowed and nearly same diameter along entire length with pair of distal protuberances ( Rafael & Cumming 2009, figs 1E, 2E).................................................... M. ferrugineus species-group

- Hypandrium variable, generally widened, with somewhat translucent membranous area basally ( Rafael & Marques 2021, figs 10D, 11J, 13N)..................................................................... unplaced species-group

Figures

FIGURE 1. Macrostomus megatarsus sp. nov., paratype male. A, habitus; B, wing; C, tergite 8, dorsal view; D, tergite and sternite 8, lateral view; E, epandrium and cerci, lateral view; F, epandrium, lateral view; G, cerci lobes, dorsolateral view; H, detail of the cercal bridge and subepandrial sclerite, anterior view; I, hypandrium, ejaculatory apodeme, and phallus, lateral view; J, holotype labels. Abbreviations: a ce = anterior cercus; ce brd = cercal bridge, ej apod = ejaculatory apodeme, hypd = hypandrium, m ce = median cercus, p ce = posterior cercus, ph = phallus, sbepand scl = subepandrial sclerite.

FIGURE 2. Macrostomus megatarsus sp. nov., paratype female. A, habitus; B, wing; C, tergites 8, 9+10 and cerci, dorsal view; D, sternite 8, ventral view; E, tergite and sternite 8 to cerci, lateral view (sternite 8 outlined); F, spermatheca; G, eggs. Abbreviations: gen fk = genital fork, tg = tergite, st = sternite. Figures C, D, and E at same scale.

FIGURE 3. Macrostomus polleti sp. nov., paratype male.A, habitus; B, wing; C, tergite 8 and sternite 8, dorsal view; D, tergite and sternite 8, lateral view; E, terminalia, lateral view (epandrium outlined); F, detail of the cercal bridge and subepandrial sclerite, anterior view; G, cerci lobes, posterior view; H, hypandrium (below) and detached phallus and ejaculatory apodeme, lateral view. I, holotype labels. Abbreviations: a ce = anterior cercus; ce brd = cercal bridge, m ce = median cercus, p ce = posterior cercus, ph = phallus, sbepand scl = subepandrial sclerite.

FIGURE 4. Macrostomus polleti sp. nov., paratype female. A, habitus; B, wing; C, tergites 8, 9+10 and cerci, dorsal view; D, sternite 8 and genital fork, ventral view; E, tergite and sternite 8 to cerci, lateral view; F, spermatheca and spermathecal duct. Figures C, D, and E at same scale.