Tachydromia Meigen, 1803

Gonçalves, Ana Rita, Grootaert, Patrick, Andrade, Rui, Paulo, Octávio S. & Mengual, Ximo, 2021, Revision of the morphology, phylogenetic relationships, behaviour and diversity of the Iberian and Italian ant-like Tachydromia Meigen, 1803 (Diptera: Hybotidae), European Journal of Taxonomy 732, pp. 1-56 : 14-16

Genus Tachydromia Meigen, 1803

Key to the non-macropterous species of Tachydromia

This key treats the 13 currently known non-macropterous species of Tachydromia , including the 10 antlike Tachydromia from the Iberian Peninsula and Italy.

1. Halteres present ................................................................................................................................. 2

– Halteres absent................................................................................................................................... 4

2. Stenopterous wing, reduced to yellowish stub, in both sexes ............................................................. .................................................................. Tachydromia rossica Shamshev, 1994 (Russian Far East)

– Brachypterous wing in both sexes ..................................................................................................... 3

3. Wings ⅔ as long as abdomen. Dorsocentral bristles short. Postpronotal lobe with minute, fine, pale bristles....................................................... Tachydromia microptera (Loew, 1864) (Central Europe)

– Wings 3/5 as long as abdomen. Dorsocentral bristles long. Postpronotal lobe with dark long bristles...................................................................... Tachydromia schnitteri Stark, 1996 ( Germany)

4. Females, without globous structure at abdominal apex ( Figs 16J , 17B, H ) .................................... 14

– Males, with globous structure (visible male terminalia) at abdominal apex ( Figs 16I , 17A, C )....... 5

5. Wings completely absent .............................................................. Tachydromia iberica ( Arias 1919)

– Wings either present as vestiges (micropterous) or stalk-like process (stenopterous) ( Figs 20A, C, E, G , 21 A–B, D, F, 22)........................................................................................................................... 6

6. Micropterous ( Figs 20A , 22 ) ............................................................................................................. 7

– Stenopterous ( Figs 20C, E, G , 21 A–B, D, F) .................................................................................... 8

7. Palpi and antennae black; postpedicel lanceolate, ca 1.5 times as long as pedicel; wing is a single lobe, usually longer than wide, brownish, covered with microtrichia, at most with a single distinct seta ( Fig. 20A ) ................................. Tachydromia ebejeri Gonçalves, Grootaert & Andrade sp. nov.

– Palpi yellow; scape and pedicel yellow, postpedicel brown; postpedicel sub-conical, similar length as pedicel; wing roundish, bilobed, brownish, covered in microtrichia and bearing distinct setae ( Fig. 22 ) ................................................................. Tachydromia apterygon Plant & Deeming, 2006

8. Antennae overall yellow and / or light brown, postpedicel roundish, approximately as long as pedicel................................................................................................................................................ 9

– Antennae black; postpedicel sub-conical or lanceolate, longer than pedicel ...................................11

9. Fore tibia black, stout and inflated; mid tibia with 1 projection at anteroventral apical surface ( Fig. 19 E–F)................................................................ Tachydromia semiaptera (Gil Collado, 1923)

– Fore tibia yellow, as wide as mid and hind tibiae; mid tibia with 2 projections at apical surface ( Fig. 19 B–C) .................................................................................................................................... 10

10. Wing lobe with complex black and white pattern ( Fig. 21B ), antennae and legs overall yellow, mesonotum slightly convex ............................................. Tachydromia pieltaini (Gil Collado, 1936)

– Wing lobe white at basal half and black distally ( Fig. 21A ), antenna and legs yellow and brown, mesonotum convex and somewhat humped ........................... Tachydromia pandellei ( Séguy, 1941)

11. Wing with only slightly lobed distal apex ( Fig. 21F ); tergites bearing few and scattered setae; legs black, except for pale brown ventral and dorsal posterior surface of coxae, trochanter and basal ventral surface of femora and knees; right epandrial lamella convex, globose ( Fig. 14A )................. ................................................... Tachydromia stenoptera Gonçalves, Grootaert & Andrade sp. nov.

– Wing with distinctively lobed distal apex ( Figs 20C, E, G ); tergites totally covered by setae; legs with black and yellow / pale brown pattern; right epandrial lamella with a different general shape ... ......................................................................................................................................................... 12

12. Distinct prescutellar setae absent, scutellum with two setae present medially; fore tibia with sparse ciliation of hair-like setae (shorter than maximum diameter of tibia) with slightly curved tips; left surstylus of terminalia with long setae on apical margin ( Fig. 4C )..................................................... ……… ...................................... Tachydromia cantabrica Gonçalves, Grootaert & Andrade sp. nov.

– Distinct prescutellar and scutellar setae present; fore tibia with dense ciliation of long hair-like setae with curved tips; left surstylus with setulae on apical margin ( Figs 9C , 10C )................................ 13

13. Wing with bilobed distal apex, produced into long digitation on distal margin ( Fig. 20E ); legs black with the following segments yellowish-brown: coxa, trochanter, knee, anterior and ventral surfaces of fore and mid femora, base of fore and mid tibiae, basal 4/5 surface of tarsomere 1, basal surface, ⅔ of mid and hind tarsomere 2 .............. Tachydromia lusitanica (Grootaert, Shamshev & Andrade)

– Wing with lobed distal apex, without a distinct digitation on distal margin ( Fig. 20G ); legs black, excepting trochanters, knees and tarsomere 1 and 2 which are yellowish to brown ......................................... Tachydromia nigrohirta Gonçalves, Grootaert & Andrade sp. nov.

14. Wings completely absent ............................................................. Tachydromia iberica ( Arias, 1919)

– Wings either present as vestiges (micropterous) or stalk-like process (stenopterous) ( Figs 20B, D, F, H , 21C, E, G ) ................................................................................................................................... 15

15. Antennae yellow and /or light brown, postpedicel roundish, approximately as long as pedicel ..... 16

– Antennae black; postpedicel sub-conical or lanceolate, longer than pedicel .................................. 19

16. Stenopterous ( Fig. 21C )................................................................................................................... 17

– Micropterous ( Fig. 21E ) .................................................................................................................. 18

17. Antennae and legs overall yellow; scutellum bearing two setae; abdomen shiny black with grey microtrichia covering only last apical tergite and almost all sternites................................................. ......................................................................................... Tachydromia pieltaini (Gil Collado, 1936)

– Antennae and legs yellow and brown; scutellum lacking distinct setae; abdomen black, uniformly covered with grey microtrichia ............................................... Tachydromia pandellei ( Séguy, 1941)

18. Palpi yellow in ground colour; wing bilobed, roundish, apical margin of posterior lobe bearing one long seta, anterior lobe bearing three shorter setae.............................................................................. ............................................................................... Tachydromia apterygon Plant & Deeming, 2006

– Palpi black in-ground colour; wing as single lobe, roundish, bearing one long seta and one short seta on apical margin ( Fig. 21E ) ........................................ Tachydromia semiaptera (Gil Collado, 1923)

19. Four prescutellar setae and four scutellar setae; wing as single lobe, usually longer than wide, at most with single distinct seta present ( Fig. 20B ); coxae, femora and most of tibia dark brown to black; trochanters, knee, anteroventral surface of tibia, distal ¼ of tarsomere 1, distal half of tarsomere 2 and following tarsomeres, yellowish ................................................................................................... ......................................................... Tachydromia ebejeri Gonçalves, Grootaert & Andrade sp. nov.

– Different number of prescutellar and scutellar setae; wing bilobate, roundish, with distinct setae ( Figs 20D, F, H , 21G ) ...................................................................................................................... 20

20. Tergites with few and scattered setae, mostly present on posteromarginal surface and near spiracles; sternites with evenly distributed setae; legs almost completely black, excepting very small brown portions, specifically: ventral and dorsal posterior surfaces of coxae, trochanter, basal ventral surface of femora and knees................... Tachydromia stenoptera Gonçalves, Grootaert & Andrade sp. nov.

– Tergites and sternites with evenly distributed setae; legs with different colour pattern of black and yellow to brown ............................................................................................................................... 21

21. Postpronotal lobe bearing ca 4 setae laterally; wings bilobate, bearing one seta on apical margin of each lobe ( Fig. 20D ); legs black with following segments pale brown/yellowish: apical portion of coxae, trochanters, basal portion of mid and hind femora, distal apical surface of fore and mid femora, knees, basal surface of tarsomere 1 and basal ⅔ surface of tarsomere 2 ................................................ Tachydromia cantabrica Gonçalves, Grootaert & Andrade sp. nov.

– Postpronotal lobe bearing more than 4 setae laterally; wings bilobate, bearing more than two setae on both lobes combined ( Fig. 20F, H ); legs with a different colour pattern.................................... 22

22. Legs black, except for trochanters, knees and tarsomeres 1 and 2 yellowish to brown ...................... ................................................... Tachydromia nigrohirta Gonçalves, Grootaert & Andrade sp. nov.

– Legs black with following segments yellowish-brown: coxa, trochanter, knee, anterior and ventral surface of fore and mid femora, base of fore and mid tibia, basal4/5 surface of tarsomere1, basal surface ⅔ of mid and hind tarsomere 2 .... Tachydromia lusitanica ( Grootaert, Shamshev & Andrade, 2009)

General diagnosis of the Iberian and Italian ant-like species of Tachydromia

The Iberian and Italian ant-like Tachydromia species can be jointly characterized by lacking halteres and functional wings (apterous, micropterous or stenopterous). Considering their overall morphology (e.g., shape and colouration of palpus and pubescence of legs), it can be said that Iberian species are generally more related to the arrogans species group than to any other; however, various species differ from this group in having a shorter stylus 1.5 times as long as the antenna ( T. semiaptera , T. pieltaini and T. pandellei ) and/or for having male genitalia large and globular ( T. stenoptera sp. nov.). Plant & Deeming (2006) suggested that T. apterygon is more related to terricola group. They are quick and agile runners and often move their abdomens up and downwards, resembling ants or certain flightless parasitic wasps.

Figures

Fig. 16. Habitus of live specimens of the Iberian ant-like Tachydromia Meigen, 1803 and the Italian flightless Tachydromia. Males are pictured in the left column, females in the right.A–B. T. iberica (Arias, 1919). C–D. T. semiaptera (Gil Collado, 1923). E–F. T. pieltaini (Gil Collado, 1936). G–H. T. pandellei (Séguy, 1941). I–J. T. apterygon Plant & Deeming, 2006 (Italy).

Fig. 17. Mounted specimens of the Iberian ant-like Tachydromia Meigen, 1803. Males are pictured in the left column, females in the right. A–B. T. lusitanica (Grootaert, Shamshev & Andrade, 2009). C–D. T. nigrohirta Gonçalves, Grootaert & Andrade sp. nov. E–F. T. ebejeri Gonçalves, Grootaert & Andrade sp. nov. G–H. T. stenoptera Gonçalves, Grootaert & Andrade sp. nov. Scale bars: 1 mm.

Fig. 20. Drawings of the tip of stenopterous wings and images obtained by scanning electron microscope (SEM) of the micropterous wings. Males are pictured in the left column, females in the right. A–B. T. ebejeri Gonçalves, Grootaert & Andrade sp. nov. C–D. T. cantabrica Gonçalves, Grootaert & Andrade sp. nov. E–F. T. lusitanica (Grootaert, Shamshev & Andrade, 2009). G–H. T. nigrohirta Gonçalves, Grootaert & Andrade sp. nov. Scale bars: A–B, D, F, H = 10 µm; C, E, G = 50 µm.

Fig. 21. Drawings of the tip of stenopterous wings and images obtained by scanning electron microscope (SEM) of the micropterous wings. Males are pictured in the left column, females in the right. A, C. T. pandellei (Séguy, 1941). B–C. T. pieltaini (Gil Collado, 1936). D–E. T. semiaptera (Gil Collado, 1923). F–G. T. stenoptera Gonçalves, Grootaert & Andrade sp. nov. Scale bars: A–D, F = 50 µm; E, G = 10 µm.

Fig. 22. Image obtained by scanning electron microscope (SEM) of the micropterous wing of a male of Tachydromia apterygon Plant & Deeming, 2006. Scale bar: 10 μm.

Fig. 19. Images obtained by scanning electron microscopy of the spur-like structures present on the apical portion of the male mid tibia. A. T. lusitanica (Grootaert, Shamshev & Andrade, 2009). B. T. pandellei (Séguy, 1941). C. T. pieltaini (Gil Collado, 1936). D. T. ebejeri Gonçalves, Grootaert & Andrade sp. nov. E–F. T. semiaptera (Gil Collado, 1923). G. T. stenoptera Gonçalves, Grootaert & Andrade sp. nov. H. T. cantabrica Gonçalves, Grootaert & Andrade sp. nov. I. T. nigrohirta Gonçalves, Grootaert & Andrade sp. nov. J. T. apterygon Plant & Deeming, 2006. Scale bars: 10 µm.

Fig. 14. Terminalia of Tachydromia stenoptera Gonçalves, Grootaert & Andrade sp. nov., holotype (RBINS). A. Right surstylus and right epandrial lamella. B. Epandrium with cerci. C. Left epandrial lamella and left surstylus. D–E. Right surstylus. Scale bar: 0.1 mm.

Fig. 4. Terminalia of Tachydromia cantabrica Gonçalves, Grootaert & Andrade sp. nov., holotype (RBINS). A. Right surstylus and right epandrial lamella. B. Epandrium with cerci. C. Left epandrial lamella and left surstylus. D. Right surstylus. Scale bar: 0.1 mm.

Fig. 9. Terminalia of the holotype of Tachydromia lusitanica (Grootaert, Shamshev & Andrade, 2009) from Portugal, Braga, Gilmonde (RBINS). A. Right surstylus.B. Epandrium with cerci.C. Left epandrial lamella and left surstylus. Figure adapted from Grootaert et al. 2009.

Fig. 10. Terminalia of Tachydromia nigrohirta Gonçalves, Grootaert & Andrade sp. nov., holotype (RBINS). A. Right surstylus and right epandrial lamella. B. Epandrium with cerci. C. Left epandrial lamella and left surstylus. D. Right surstylus. Scale bar: 0.1 mm.