Tachydromia Meigen, 1803

Grootaert, Patrick & Shamshev, Igor V., 2012, The fast-running flies (Diptera, Hybotidae, Tachydromiinae) of Singapore and adjacent regions, European Journal of Taxonomy 5, pp. 1-162 : 18-20

Genus Tachydromia Meigen, 1803

Sicus Latreille, 1797: 158 . Type-species: Musca cimicoides Fabricius, 1781 , by subsequent designation of Latreille (1810: 443) [= Musca arrogans Linnaeus, 1761 ]. Pre-occupied by Sicus Scopoli, 1763 [ Diptera , Conopidae ].

Coryneta Meigen, 1800: 27 . Type-species: Tachydromia connexa Meigen, 1822 , by subsequent designation of Coquillett (1910: 528). Suppressed by I.C.Z.N., 1963: 339 (Opinion 678).

Tachydromia Meigen, 1803: 269 . Type-species: Musca cimicoides Fabricius , sensu Curtis, 1833: pl. 477 (by designation of Curtis 1833), misidentification [= Tachydromia connexa Meigen, 1822 ].

Sicodus Rafinesque, 1815: 130 . Type-species: Musca cimicoides Fabricius, 1781 , automatic [= Musca arrogans Linnaeus, 1761 ]. Replacement name for Sicus Latreille, 1796 .

Danistes Gistel, 1848 : XI. Type-species: Musca cimicoides Fabricius , sensu Curtis, 1833, automatic [= Tachydromia connexa Meigen, 1822 ]. An unnecessary new name for Tachydromia Meigen, 1803 .

Tachista Loew, 1864: 7 , 15. Type-species: Musca cimicoides: sensu Meigen, 1803 (by subsequent designation of Coquillett 1903: 258), misidentification [= Tachydromia connexa Meigen, 1822 ].

Tachysta : authors, error or emendation.

Recognition

Recognised by the following combination of characters: eyes broadly separated on frons, contiguous on face, bare; postpronotal lobe well differentiated; scutum usually distinctly longer than broad; fore femur thickened, mid legs more or less slender; wing often banded or spotted, with veins A 1 and CuA 2 absent (cell cup absent).

Diagnosis

Small to medium-sized (1.0 to 3.5 mm), usually largely shining, ant-like flies. Eyes separated on frons, contiguous on face; ommatidia somewhat enlarged below. One pair of vertical bristles. Ocellar tubercle with 1 pair of bristles. Antenna with postpedicel conical or subglobular; stylus apical or subapical. Palpus varying in shape and length, usually with black subapical seta (sometimes absent). Thorax usually black in ground-colour and largely shining, with greatly reduced setation; scutum usually distinctly longer than broad; postpronotal lobe well differentiated; postpronotal bristle prominent or absent; mesonotal setation variable. Fore femur and tibia thickened; mid leg more or less slender, in males often modified. Wings normally developed or reduced (in non-Oriental species); usually with distinct pattern, banded, spotted or clouded; Rs rather short, originating before or near midway of vein R 1; vein R 1 long, meeting costa beyond or near wing midway; vein R 2+3 complete (except male of T. ocellata Shamshev & Grootaert ), meeting costa closer to wing apex; A 1 absent; crossvein CuA 2 absent; crossvein bm-cu usually transverse; cell br shorter than cell bm, rarely both cells of subequal length (male of T. ocellata ); cell cup absent. Abdomen with segments 1-7 unmodified (in Oriental species); no squamiform setae and gland-like intersegmental structures. Terminalia rotated 45-90° to right, of varying structure; epandrium not divided; left epandrial lamella separated from hypandrium; left surstylus usually undifferentiated from epandrial lamella; right epandrial lamella usually larger; right surstylus usually present, barely differentiated or undifferentiated from epandrial lamella; cerci separated; hypandrium usually with 2 bristles on apical portion; phallus very short; two rod-shaped apodemes (i.e. ejaculatory and ventral apodemes) present. Female usually similar to male but with unmodified structure and vestiture of mid leg, rarely ( T. ocellata ) with different pattern and venation of wing; terminalia long; tergite 8 separated from sternite 8; cercus long, slender.

Remarks

Species of Tachydromia are likely among the most attractive flies within the Hybotidae owing to their external appearance and behaviour. They are usually found running about quickly on tree-trunks, logs, stones, sand, or leaves of lower herbage resembling in some respects small hymenopterans or ants ( Chvála 1970). The group is worldwide in distribution and currently includes 110 species, of which 18 species are known from the Oriental Region. The Oriental species of Tachydromia were recently revised by Shamshev & Grootaert (2005b, 2008, 2009a) and Grootaert & Shamshev (2009a).The genus is recently also reported for the first time in Australia and six species are now known in the Australasian region ( Grootaert & Shamshev 2011).

Only a single species is reported in Singapore so far. Females are observed sporadically, but males are very rare. We do not expect many more species of Tachydromia to occur here in Singapore, because it is quite rare in the whole tropical Oriental Region, except perhaps in mountains where more species are found ( Shamshev & Grootaert 2008).

The updated key given below is based on the key compiled by Shamshev & Grootaert (2008), but it includes a species described from the South China ( Yang & Grootaert 2006), two species of Tachydromia recently described from Malaysia ( Shamshev & Grootaert 2009a) and correctly distinguishes males and females of T. ocellata .

Updated key to species of Tachydromia of the Oriental Region

1. Halter with brown to black knob ……………………............................……………………………2

– Halter entirely yellow or at most stem brownish ………..……............................………………….7

2. Wing with large brown patch on subapical part ……………………..............................…………….3

– Wing brownish infuscate leaving subapical part whitish, brown along anterior margin ……....……5

3. Fore femur with brown elongate ventral patch basally; hind femur brown on apical 1/4. Male: fore tibia mostly bare posteriorly but with rather long curved thin setae along sides of bare space ( Thailand) …………….................................................... T. tigeri Shamshev & Grootaert, 2008

– Fore and hind femora entirely yellow. Male: fore tibia unmodified ……….....................……..4

4. Tibiae almost entirely yellow, only fore tibia with subapical ventral brown patch ( Viet Nam) …… ………………..................................…………. T. achterbergi Grootaert & Shamshev, 2009

– Tibiae almost entirely dark brown, only hind tibia brownish yellow apically ( China, Guangdong).... ………………….......……………........................... T. guangdongensis Yang & Grootaert, 2006

5. Fore femur almost entirely yellowish, indistinctly brownish clouded posteriorly on subapical part; hind femur broadly brownish on middle part; hind tibia dark brown on about apical half. Male: fore tibia slightly curved (viewed dorsally), with ventral spinules becoming stronger on apical half and several spinule-like setulae posteriorly near middle ( Thailand)........ T. phu Shamshev & Grootaert, 2008

– Fore femur largely brownish; hind femur pale yellow on basal 1/5, otherwise dark brown to black. Male: fore tibia unmodified................................................................................................................6

6. Postpedicel brownish yellow, paler than scape and pedicel. Male: Right cercus with very long seta at tip ( Thailand)…….................................………. T. phanensis Shamshev & Grootaert, 2008

– Antenna entirely brownish. Male: Right cercus with several moderately long marginal setae apically ( Viet Nam)……................................................ T. annamensis Grootaert & Shamshev, 2009

7. Wing with 2 broad brownish bands separated along entire length or connected somewhere..….8

– Wing with more or less distinct brownish patch closer to wing apex or (rarer) lacking prominent pattern.........................................................................................................................13

8. Antenna yellow. Hind femur brownish on apical part, hind tibia black brown on apical 1/6-1/5…..9

– Antenna dark brown to black (sometimes basal segments somewhat darker). Hind femur and tibia largely blackish brown.......................................................................................................................10

9. Fore tibia contrastingly black on apical 1/3. Male: cerci with numerous very long setae ( Thailand; Singapore)................................................................................. T. luang Shamshev & Grootaert, 2005

– Fore tibia entirely yellow. Male: cerci covered with scattered short to moderately long setae ( Malaysia) ........................................................................................ T. malaysiensis Shamshev & Grootaert, 2009

10. Palpus pale yellow ( China, Henan)........................................ T. henanensis Saigusa & Yang, 2002

– Palpus dark..........................................................................................................................................11

11. Hind femur brown on apical 2/3 ( Thailand)............ T. monocercus Shamshev & Grootaert, 2008

– Hind femur entirely blackish brown...............................................................................................12

12. Laterotergite with thin finger-like process. Wing with bands connected on cells r 1 and r 4+5. ( China, Henan)........................................................................................ T. digitiformis Saigusa & Yang, 2002

– Laterotergite unmodified. Wing with 2 broad brown bands separated along the whole length ( India).............................................................................................. T. latifascipennis Brunetti, 1917

13. Hind femur entirely yellow...............................................................................................................14

– Hind femur at least partly brown to black.......................................................................................15

14. Fore tarsomeres 4 and 5 brown. Hind tibia brownish on about basal half ( Thailand; Viet Nam)... ..................................................................................................... T. doi Shamshev & Grootaert, 2008

– Only fore tarsomere 5 darkened on apical half. Hind tibia entirely yellow ( Thailand)................. ................................................................................ T. terricoloides Shamshev & Grootaert, 2005

15. Occiput with flattened silvery white setae on lower part. Hind femur entirely black. Wing almost entirely uniformly brownish infuscate, darker anteriorly, paler basally ( Malaysia)....................... .............................................................................. T. pahangiensis Shamshev & Grootaert, 2009

– Occiput with pale hair-like setae on lower part. Hind femur brown on apical part. Wing with different pattern.................................................................................................................................16

16. Palpus yellowish brown. Fore tibia almost entirely brownish, extreme base yellow. Wing largely finely infuscate, somewhat deeper on middle part along veins ( Thailand).................................... ......................................................................................... T. thaica Shamshev & Grootaert, 2005

– Palpus pale yellow. Fore tibia at most brownish apically. Wing with 1 or 2 brownish patches on subapical part.....................................................................................................................................17

17. Wing with 2 brownish patches on subapical part; vein R 2+3 incomplete; male ( Thailand)............ ...................................................................................... T. ocellata Shamshev & Grootaert, 2008

– Wing with 1 brownish patch on subapical part; vein R 2+3 complete............................................18

18. Only fore tarsomere 5 darkened on apical part; hind tibia yellow (Taiwan) ... T. bistigma (Bezzi, 1912)

– Fore tarsomeres 4 and 5 brown; hind tibia partly brown to black...............................................19

19. Mid tibia brown; hind tibia brown on apical 1/4; female.... T. ocellata Shamshev & Grootaert, 2008

– Mid tibia yellow; hind tibia blackish on basal 2/3 ( China, Henan).................................................. ....................................................................................... T. longyuwanensis Saigusa & Yang, 2002