Igor Ya. GRICHANOV

Grichanov, I.Ya. Afrotropical species of the genus Tachytrechus Haliday (Diptera: Dolichopodidae)

T. brittoni sp.n. from Yemen is described. A catalogue and key to Afrotropical species of Tachytrechus are given. T. indirectus (Walker) and T. capensis Curran are placed in synonymy to T. tessellatus (Macquart) and T. liberia Curran to T. luteicoxa Parent. Hercostomus melanolepis Bezzi is transferred to Tachytrechus.

I.Ya. Grichanov, All-Russian Institute of Plant Protection, Podbelskogo 3, St.Petersburg-Pushkin, 189620, Russia.

Key words: Diptera, Dolichopodidae, Tachytrechus, Tropical Africa, new species, new synonym, new combination, keys.

Introduction

The world fauna of the genus Tachytrechus Haliday includes about 160 species from all zoogeographical regions except Australian. The Afrotropical Region comprises 15 (including new) species found all over the continent. T. tessellatus (Macquart) widely distributed across Palaeotropics is also recorded from western Indian Ocean islands and African continent. T. consobrinus Haliday is known from Europe and north-western Africa (including Mali). Area of T. planitarsis Becker extends from Central Asia to North Africa and Ethiopia. South-African T. pteropodus Schiner was originally described from Brazil (?mislabelling). Afrotropical species of Tachytrechus differ from the related genera of Dolichopodinae in the complex of characters including several strong anterodorsal setae in apical half of the hind femur in addition to the true anterior subapical seta; the face is narrowed under antennae and somewhat widened towards clypeus; wing vein M1+2 usually has gentle curvation before the middle of distal part, running towards R4+5 and reaching costa far before the tip of wing; arista is short and bare; first flagellomere is usually short and suboval. Description of Hercostomus melanolepis (Bezzi, 1906) corresponds with the generic concept of Tachytrechus; moreover, none Afrotropical species of Hercostomus has several subapical anterodorsal setae on the hind femur. So, I include this species in the genus Tachytrechus. On the other hand, descriptions of T. obscoenus (Wiedemann) (Loew, 1860; Becker, 1923) include such characters unusual for Afrotropical species of the genus as black postocular setae, strong middle femur with two subapical setae and stronger hind femur with one subapical seta. The species seems to be replaced to the genus Pelastoneurus Loew. A new species is also described, revised catalogue and key to Afrotropical species of the genus are given in this paper. T. indirectus (Walker) and T. capensis Curran are placed in synonymy to T. tessellatus (Macquart) and T. liberia Curran to T. luteicoxa Parent.

Holotype and paratypes of the new species are deposited in the Natural History Museum in London [NHML]. The other material examined is also kept in the Royal Institute for Natural Sciences, Brussels [RINS], Royal Museum for Central Africa, Tervuren [RMCA] and Lund University, Sweden [Lund].
 
 

List of known species of Tachytrechus Haliday

(for references see Dyte and Smith, 1980)

Genus TACHYTRECHUS Haliday

=AMMOBATES Stannius, 1831:33, 268. Type-species: Ammobates notatus Stannius, 1831, by designation of Rondani (1856:143). [Junior homonym, preocc. Ammobates Latreille, 1809.]

=TACHYTRECHUS Stannius, 1831:261. Nomen nudum.

TACHYTRECHUS Haliday in Walker, 1851a:173 (replacement name for Ammobates Stannius).

alternatus Curran, 1924:223. South Africa; Angola (!), Uganda (!), Nigeria, Ghana (!).

bracteatus Wiedemann, 1830:652 (Dolichopus). South Africa; Malawi (!), Congo (Kinshasa).

brittoni sp.n. Yemen.

consobrinus Haliday in Walker, 1851:173 (Dolichopus). Ireland; Mali, Morocco, Europe.

elegans Parent, 1933:10. Congo (Kinshasa).

imperator Curran, 1927:181. South Africa.

insolitus Parent, 1931:39. Sierra Leone.

kenyensis Parent, 1938:409. Kenya, Congo (Kinshasa) (!).

luteicoxa Parent, 1929:177 [1930:98]. Ivory Coast, Liberia, Ghana, Sierra Leone, Nigeria (!), Cameroon (!), Uganda.

=liberia Curran, 1929:7, n.syn. Liberia.

melanolepis Bezzi, 1906:300 (Hercostomus), n. comb. Ethiopia (Eritrea); ?Madagascar.

obscoenus Wiedemann, 1830:651 (Dolichopus) [?Tachytrechus, ?Pelastoneurus]. South Africa.

petraeus Loew, 1871:283. Uzbekistan; 'Africa'.

planitarsis Becker, 1907:106. Algeria; Ethiopia, Egypt, Saudi Arabia (!), Turkmenia.

pteropodus Schiner, 1868:220. 'Brazil'; South Africa.

tessellatus Macquart, 1842:185 (125) (Dolichopus). Senegal; Gambia (!), Nigeria, Congo (Kinshasa), Burundi (!), Tanzania, Aldabra, Ethiopia, South Africa (!), Swaziland (!), Malawi, Angola (!), Namibia (!), Botswana (!), Mozambique, Madagascar, Mauritius, Seychelles, Socotra, Egypt; Oriental Region, New Caledonia.

=indirectus Walker, 1849:665 (Dolichopus; female), n.syn. 'West Africa'.

=picticornis Bigot, 1890b:293 (Neurigona). New Caledonia.

=salinarius Becker, 1902:63. Egypt.

=seychellensis Lamb, 1922:389. Seychelles.

=capensis Curran, 1924:223 (female), n.syn. South Africa.
 
 

Descriptions and new records

Tachytrechus alternatus Curran

Material examined [NHML]. Male, N. Nigeria: Zaria, Samaru, 13.III.1969 / J.C. Deeming, m.v. trap; 1 female, N.Nigeria, 4.3.1911, Dr. J.W.S. Macfie, 1912-60; 1 male, Angola (A16): 2 mls. N. Mocamedes, 29.II.1972 / Southern African Exp. B.M. 1972-1; 1 male, Angola (A11): Bruco, 26.II-2.III.1972 / Southern African Exp. B.M. 1972-1; 1 female, Angola (A40): Tundavala, 8-10 mls. NW. Sa da Bandeira, 27-29.III.1972 / Southern African Exp. B.M. 1972-1; 1 male, 2 females, Gold Coast: Tamale, November 1916, J.J. Simpson / Pres. by Imp. Inst. Ent. B.M. 1935-576; 1 male. Uganda: Ruwenzori Range, XII.1934-I.1935. B.M. E. Afr. Exp. B.M. 1935-203 / Kilembe, 4500 ft., F.W. Edwards.

Diagnosis. T. alternatus is characterised by the following features. Scape and pedicel yellow. 1st flagellomere mostly black. Costa without thickening in 2nd part. M1+2 straight in apical part. All coxae black. Legs simple, mostly yellow; hind tibia black at apex; hind tarsus entirely black. Fore tibia and tarsus with ventral pile of microscopic yellow hairs. Middle femur with shallow ventral excavation in basal third. Cercus dark-brown, rounded-oval, with long hairs, especially long ventrally.

Remark. Specimens from Congo (Kinshasa) determined by P. Vanschuytbroeck as T. alternatus (RMCA, examined) belong to the genus Pelastoneurus. So, the species should be excluded from the fauna of Congo (Kinshasa).

Distribution: South Africa; Angola (!), Uganda (!), Nigeria, Ghana (!).

Tachytrechus bracteatus (Wiedemann)

Material examined. 1 male, S. Africa: Pirie, Dam, II.1944, J. Omer-Cooper, B.M. 1948-276 [NHML]; 3 males, Nyasaland, Kotakota, Dr. J.E.S. Old., 1911-221 [NHML]; 2 males, RSA: Cape Prov. 2 km NW. Darling, 170 m, 33°22'S, 18° 22'E, 04.X.1994, Loc. 4, leg. R. Danielsson [Lund]; 1 female, RSA: Cape Prov. Koomplanskloof, 10 km S Citrusdal, 200-270 m, 32°40'S, 19° 01'E, 04-08.X.1994, Loc. 8, leg. R. Danielsson [Lund].

Diagnosis. Antenna black. Legs simple, mostly yellow. Femora black in basal half. Fore femur ventrally bare. Middle femur with shallow ventral excavation in basal fourth. Wing with dull spots at m-cu and M1+2 curvation. Costa thickened. Cercus black, broad, semilunular, with acute basoventral apex and long black simple cilia along ventral margin.

Distribution: South Africa; Malawi (!), Congo (Kinshasa).

Tachytrechus brittoni sp.n. (Fig. 1)

Holotype. Male, W. Aden Prot., Jebel Harir, 5200 ft., 26.X-6.XI.1937 / B.M. Exp. to S.W. Arabia, H. Scott & E.B. Britton, B.M. 1938-246 [NHML].

Paratypes. Male with the same label; female, W. Aden Prot., Jebel Jihaf, Wadi Leje, 6300 ft., 14.X.1937 / near waterfall / B.M. Exp. to S.W. Arabia, H. Scott & E.B. Britton, B.M. 1938-246 [NHML].

Description. Male. General coloration of body green-black. Frons and face greenish-black, densely brownish pollinose. One vertical, one postvertical, a pair of ocellar strong setae present. Upper postocular setae black; lower postocular white; ventral postcranium with white setae. Eyes and face practically bare. Face the narrowest under antennae, gently widened towards clypeus; ratio of its width below antennae to height 13 : 60; clypeus not reaching lower margin of eyes, convex downward. Antenna shorter than height of head. Scape yellow, brownish dorsally; pedicel black-brown; 1st flagellomere black, suboval, slightly longer than high, with somewhat pronounced apicodorsal obtuse angle and microscopic hairs; arista middorsal, black, bare. Length ratio of scape to pedicel to 1st flagellomere to arista, 10 : 10 : 13 : 53. Palpus and proboscis very small, with short hairs.

Legs mostly yellow; all coxae black, whitish pollinose; fore femur in basal half, middle and hind femora at base black, last segments of middle and hind tarsi brown at their apices. Fore coxa with black hairs and several short apical setae. Fore femur with ventral row of 4-5 strong setae in apical half, as long as diameter of femur. Fore tibia slightly narrowed in apical third before apex, with 3 anterodorsal, 2-3 posterodorsal, 2 posteroventral setae, 2-3 apical setae. Fore tarsus simple, without ventral pile; 1st to 4th segments each with elongate apicoventral setula. Length ratio of fore coxa to femur to tibia to tarsus (segments from first to fifth), 65 : 110 : 88 : 32 : 13 : 12 : 11 : 13. Middle femur with 1 subapical anterior seta, 1-2 ventral rows of microscopic black spicules in basal 2/3 and small ventral swelling at basal third. Middle tibia with 4-5 anterodorsal, 3 posterodorsal, 3-5 ventral and 5 apical setae. 1st to 4th segments of middle tarsus each with elongate apicoventral setula. Length ratio of middle coxa to femur to tibia to tarsus (segments from first to fifth), 45 : 125 : 135 : 67 : 28 : 20 : 17 : 20. Hind femur with anterodorsal row of 4 setae in apical half in addition to subapical anterior seta. Hind tibia with 5-6 antero-, 5-6 posterodorsal, 1 strong and 3-4 hairlike ventral, 2 apical setae. Hind basitarsus with 1 basoventral, 3-4 short apical setae; 2nd-4th segments with elongate apicoventral setulae. Length ratio of hind coxa to femur to tibia to tarsus (segments from first to fifth), 35 : 135 : 165 : 50 : 50 : 30 : 24 : 20.

Thorax grey pollinose. 6 dorsocentral setae, 2 rows of short acrostichals. Propleura with 1 strong seta and numerous black hairs above coxa, several upper black hairs. Scutellum with 2 strong and 2 fine lateral setae.

Wing practically hyaline, without distinct spots. Costal vein with thickening in middle of 2nd part. R1 0.4 times as long as wing. R2+3 and R4+5 straight except their slightly divergent apices. Ratio of part of costa between R2+3 and R4+5 to this between R4+5 and M1+2, 41 : 6. M1+2 in distal part nearly straight, joining costal vein far before wing tip. Distal part of M1+2 slightly longer than proximal part. Crossvein m-cu straight, oblique. Cross-vein m-cu equal in length to apical part of CuA1. Anal vein distinct, nearly reaching to wing margin; anal angle right. Lower calypter yellow, with black setae. Halters yellow.

Abdomen metallic dark-green, whitish pollinose, with black hairs and marginal setae. 8th segment black, with short sparse black hairs. Epandrium greenish-black, large. Hypandrium hook-shaped at apex, with middorsal hook. Epandrial lobe prominent, with two apical setae. Surstylus brown, two pairs, covered with fine and thick setae as figured. Cercus brown-black, rounded, with right basoventral angle and straight and curved black cilia shorter than diameter of cercus.

Female. Female similar to male except lacking male secondary sexual characters, otherwise as follows. Face somewhat wider, 1.5 times wider than height of 1st flagellomere. Fore femora with several elongate ventral setulae in apical third. Fore basitarsus slightly longer than neat two segments; 2nd-5th segments of equal length. Hind basitarsus slightly longer than 2nd segment. Fore tibia with 3 antero-, 2 posterodorsal, 2 ventral setae. Middle tibia with 5 antero-, 4 posterodorsal, 3 antero-, 4 posteroventral setae. Costa inconspicuously thickened in the middle of 2nd part.

Length: body without antennae 5.2 mm, antenna 1.1 mm, wing-length 4.6 mm, wing-width 1.4 mm, hypopygium 1.7 mm.

Diagnosis. The new species is keyed to T. tessellatus, differing from the latter in black pedicel of antenna, black at base femora, presence of ventral row of setae on fore femur and straight M1+2. T. brittoni is closely related to T. bracteatus, differing in mostly yellow scape, presence of ventral row of setae on fore femur, hyaline wing and more rounded cercus with shorter cilia. It is also keyed to Palearctic T. sogdianus Loew from Uzbekistan (Stackelberg, 1941), differing from this species in mostly yellow middle and hind femora, entirely yellow tibiae, only one subapical seta on middle femur, and hypopygium morphology.

Distribution: Yemen.

Tachytrechus consobrinus (Haliday)

Specimens from Congo (Kinshasa) determined by P. Vanschuytbroeck as T. consobrinus (RMCA, examined) belong to the genus Pelastoneurus and Tachytrechus tessellatus. So, the species should be excluded from the fauna of Congo (Kinshasa).

Distribution: Ireland; Mali, Morocco, Europe.

Tachytrechus elegans Parent

Type material examined. Holotypus, Male [red label] / Musee du Congo, Ituri: Sesenge: Ndua (Farnoye), 15.II.1930, A. Collart / R. Det. N. 2414 / Tachytrechus elegans n.sp. Type. O. Parent [RMCA].

Diagnosis. T. elegans differs from other species in yellow scape and pedicel, flattened in apical third and white in apical fourth fore tibia, all tarsi simple, and brown rounded-oval cercus with short hairs.

Distribution: Congo (Kinshasa).

Tachytrechus imperator Curran

Material examined. 1 male, S. Africa: Cape Province, Somersetwest Distr., J. Balfour-Browne, B.M. 1957-797 / Sir Lowery Pass, Steenbrass Dam., 10.III.1957, Roadside / Stn. No. 31 [NHML].

Diagnosis. T. imperator differs from other species in entirely black antenna and legs. Wing without spots; costa thickened; M1+2 weakly sinuate in distal part. Legs simple; femora without long setae, with elongate ventral hairs. The species differs from closely related T. petraeus in subtriangular, rather than rounded, cercus.

Distribution: South Africa.

Tachytrechus kenyensis Parent

Material examined. Male, Kenya: 24-29.XII.1970, A.E.Stubbs, B.M. 1972-211 / Meru, 5-7 000 feet [NHML]; 2 males, Congo belge: Ruanda, Ruhengeri (Moruhugu), 1800--1825 m, 6.II.1935, G.F. de Witte: 1068 / P. Vanschuytbroeck det., 1950, Tachytrechus petraeus Loew; 1 male, Coll. Mus. Congo, Kamogobe (Sud Masisi), 4.III.1936, L. Lippens (48-49) / P. Vanschuytbroeck det. 195?, Tachytrechus petraeus Loew; 1 male, Congo belge: P.N.A., Nyasuronge (riv.), pres Mugando, 21.IV.1945, G.F. de Witte: 19 / P. Vanschuytbroeck det., 1950, Tachytrechus petraeus Loew [RMCA].

Diagnosis. Scape and pedicel yellow; 1st flagellomere black. Wing maculated at m-cu at M1+2 curvation. Costa thickened in basal section (males). Legs simple. All coxae black. Fore femur mostly black; other podomeres dirty-yellow, partly blackish; middle femur with shallow ventral excavation in basal third; fore tibia and tarsus slightly thickened. Cercus black-brown, subtriangular, with distinct apicoventral and apicodorsal angles, convex distal margin and simple black cilia half as long as cercus width.

Distribution: Kenya, Congo (Kinshasa) (!).

Tachytrechus luteicoxa Parent

Type material examined. Paratypes [red label], 2 males, 2 females / Musee du Congo, Liberia: Moala, 31.X.1926, Dr. J. Bequaert / R. Det. 1954-T / Paratype, Tachytrechus liberia Curran [yellow label] / Tachytrechus liberia Curran, det. C.H. Curran [RMCA].

Additional material examined. 2 males, 1 female, Nigeria, Ogoja County, 10 June 1961 / Mus. Roy. Afr. Centr., don P. Vanschuytbroeck / P. Vanschuytbroeck det. Tachytrechus obscoenus Wied. [RMCA]; 1 female, Cameroon Republic: West Cameroons, Bolo, 30.I.1970, R.H.L. Disney [NHML]; 1 female, U.C. Ibadan, 21.8.1957, Coll. G.H. Caswell / Centrosema pubescens / Leaf / Cent. 210 / 114 / C.I.E. Coll. No 16044 [NHML].

Diagnosis. Differs from other species in mostly yellow antenna and legs including fore coxa; legs simple; costa thickened in basal part. Male face golden, female face whitish. Fore tibia with 3 antero-, 1 posterodorsal, 2 anteroventral setae; fore tarsus without pile. Middle tibia with 3 antero-, 3 posterodorsal, 3 ventral setae. Hind tibia with 4 antero-, 4 posterodorsal, 3 ventral setae. Length ratio of basitarsus to next segment (legs I, II, III), 2.5 : 1, 2.5 : 1, 2/3 : 1. M1+2 with angular curvation before the middle of apical part. Apical part of CuA1 2/3 the length of m-cu. Cercus brown, somewhat widened distad, with widely rounded angles and short, slightly curved cilia.

Remark. Parent (1929; publication date is 30 November) included T. luteicoxa in his key to African species of Tachytrechus, although the full description was published in 1930. Paratypes of T. liberia Curran (1929; publication date is 7 December) are identical to detailed description of T. luteicoxa (Parent, 1930).

Distribution: Ivory Coast, Liberia, Ghana, Sierra Leone, Nigeria (!), Cameroon (!), Uganda.

Tachytrechus obscoenus (Wiedemann)

Remark. Specimens from Congo (Kinshasa) determined by P. Vanschuytbroeck as T. obscoenus (RMCA, examined) belongs to the genus Diaphorus (female) and Tachytrechus luteicoxa (2 males, 1 female). So, the species should be excluded from the fauna of Congo (Kinshasa).

Distribution: South Africa.
 
 
 
 

Tachytrechus petraeus Loew

Remark. Specimens from Congo (Kinshasa) determined by P. Vanschuytbroeck as T. petraeus (RMCA, examined) belongs to T. kenyensis. So, the species should be excluded from the fauna of Congo (Kinshasa). Becker (1923) mentioned T. petraeus for "Africa", basing on specimens from Winthem’s Sammlung (des Wiener Hoffmuseums). In his monograph he cited this collection one more time under Tachytrechus obscoenus collected from Cape (South Africa). So as T. petraeus and T. imperator (described from South Africa) are poorly distinguished from one another, I incline to refer the Becker’s record of T. petraeus to the second species.

Distribution: Uzbekistan; ?Africa.

Tachytrechus planitarsis Becker

Material examined [NHML]. Male, Saudi Arabi, Bahara, March 1977, Dr. Buttiker; 1 male, 1 female, Saudi Arabien, W. Buttiker / Bahara, 29.9.1976 and 26.10. 1976; 3 females, Saudi Arabien, W. Buttiker / Salbukh, 20.8.1976.

Diagnosis. Scape and pedicel yellow; 1st flagellomere mostly black. All coxae black; femora and tibia simple, mostly yellow; male femora sometimes largely black; 1st to 5th tarsomeres of fore tarsus slightly enlarged and flattened, with dorsal comb of elongate setulae; middle tibia with 4 antero-, 3 posterodorsal and 2 ventral setae. Wing without spots; costa thickened in basal section (males); M1+2 strongly curved at basal third of distal part. Cercus yellow, subtriangular, with pointed basoventral process.

Distribution: Algeria; Ethiopia, Egypt, Saudi Arabia (!), Turkmenia.

Tachytrechus pteropodus Schiner

Material examined. 3 males, 4 females, S. Africa (7), False Bay, 2 mls. E. Muizenburg, 3.I.1972 / Southern African Exp. B.M. 1972-1; 1 male, S. Africa (13), Panne N.R., Cape Province, 5-6.I.1972 / Southern African Exp. B.M. 1972-1.

Description. Male. General coloration of body green-black. Frons and face black, densely whitish pollinose. One vertical, one postvertical, a pair of ocellar strong setae present. Upper postocular setae black; lower postocular white; ventral postcranium with long white setae. Eyes and face practically bare. Face the narrowest under antennae, gently widened towards clypeus; ratio of its width below antennae to height 8 : 27; clypeus nearly reaching lower margin of eyes, slightly convex downward. Antenna shorter than height of head. Scape and pedicel yellow; 1st flagellomere black, suboval, slightly longer than high, with indistinct anterior angles; arista dorsal, black, bare. Length ratio of scape to pedicel to 1st flagellomere to arista, 16 : 13 : 15 : 39. Palpus and proboscis very small, with short hairs.

Legs mostly yellow; all coxae black; fore femur in basal half, middle femur narrowly at base, hind femur in basal fifth, fore tibia anteriorly in middle and all tarsi from the end of 3rd segment black. Fore coxa with black hairs and several apical setae. Fore femur with antero- and posteroventral rows of black hairs, half as long as maximum diameter of femur. Fore tibia strongly enlarged and flattened anteriorly in middle half, convex posteriad; anterior flattening covered with pile of short white hairs; 3-4 ventral at base, 4-5 dorsal, 1-2 posteroventral setae; short apical anterior tooth bearing comb of short light setulae. Fore tarsus simple. Length ratio of fore coxa to femur to tibia to tarsus (segments from first to fifth), 70 : 120 : 98 : 35 : 16 : 15 : 10 : 15. Middle femur with 1 subapical anterior seta, antero- and posteroventral rows of black hairs, half as long as maximum diameter of femur. Middle tibia with 4 anterodorsal, 2 dorsal, 1 posterodorsal, 5 apical setae. Middle basitarsus strongly enlarged and flattened laterally, slightly longer than wide at apex, with dorsal row of 3 strong flat spines (each accompanied by small seta), 1-2 basoventral setae. 2nd tarsomere short, with apicoventral flat lobe, as long as 2nd segment, and 2 dorsal flat spines. 3rd segment thin, slightly flattened at base, with row of 3 dorsal cilia, 3-4 times longer than diameter of tarsomere; 4th and 5th segments simple. Length ratio of middle coxa to femur to tibia to tarsus (segments from first to fifth), 55 : 135 : 160 : 35 : 25 : 65 : 28 : 25. Hind femur with anterodorsal row of setae in apical half in addition to subapical anterior seta. Hind tibia with 5-6 antero-, 5-6 posterodorsal, 4-5 fine ventral, 2-3 apical setae. Hind basitarsus with 1 basoventral, 3-4 short apical setae; 2nd-4th segments with elongate apical setulae. Length ratio of hind coxa to femur to tibia to tarsus (segments from first to fifth), 45 : 150 : 180 : 57 : 73 : 56 : 33 : 22.

Thorax grey pollinose. 6 dorsocentral setae, 2 rows of short acrostichals. Propleura with 1 strong seta and several black hairs above coxa, several upper black hairs. Scutellum with 2 strong setae and 2 lateral hairs.

Wing hyaline, greyish along costa, with dull spots at m-cu and M1+2 curvation. Costal vein with thickening in middle of 2nd part. R1 0.4 times as long as wing. R2+3 and R4+5 straight. Ratio of part of costa between R2+3 and R4+5 to this between R4+5 and M1+2, 40 : 6. M1+2 with angular curvation before middle of distal part. M1+2 joins costal vein far before wing tip. Distal part of M1+2 equal in length to proximal part. Crossvein m-cu slightly sinuate, oblique. Ratio of cross-vein m-cu to apical part of CuA1, 34 : 27. Anal vein distinct, not reaching to wing margin; anal angle right. Lower calypter yellow, with black setae. Halters yellow.

Abdomen metallic dark-green or olive-black, with black hairs and marginal setae. 8th segment black, with short sparse black hairs. Epandrium black, large. Surstylus brown. Cercus brown-black, subtriangular, with convex distal margin bearing black simple cilia equal in length to cercus.

Female. Female similar to male except lacking male secondary sexual characters, otherwise as follows. Face somewhat wider, nearly twice wider than height of 1st flagellomere. Fore and middle tarsi simple, with regularly decreasing in length segments bearing elongate apical setulae. Fore tibia with 3 antero-, 3 posterodorsal, 2 ventral setae. Middle tibia with 4-5 antero-, 4 posterodorsal, 2-3 antero-, 3-4 posteroventral setae. Costa inconspicuously thickened in the middle of 2nd part. Two females have brownish-red scape and pedicel.

Length: body without antennae 5.3--5.7 mm, antenna 1.1 mm, wing-length 5.0 mm, wing-width 1.4 mm, hypopygium 2.0 mm.

Diagnosis. The species is quite distinct in fore tibia strongly enlarged and flattened anteriorly in middle half and middle tarsomeres 1-2 strongly enlarged and flattened laterally (see Figs. in Becker, 1921). Female is close to T. alternatus, differing in angular curvation in apical part of M1+2.

Remark. T. pteropodus was originally described from "Brasilien" (Schiner, 1868) together with numerous tropical dipteran species collected during the voyage around the world of the frigate Novara not only in South America, but also in South Africa (Cape Peninsula), Ceylon, Australia etc. As I know, nobody recorded original material for this species from Neotropics since that time. I think that the single type male was likely to be mislabelled by collectors. Drawings by Becker (1921) were made from African specimens. So, T. pteropodus should be, probably, excluded from the fauna of the New World.

Distribution: ?Brazil; South Africa.

Tachytrechus tessellatus Macquart

Material examined. Male, Musee du Congo, S.Afr.: East London, 28.4.1925 (H.K. Munro), ex coll. Curran / Tachytrechus capensis, det. C.H.Curran; 1 male, 2 females, Coll. Mus. Congo, Madagascar: Maroansetra, XII.1949, J. Vadon / P. Vanschuytbroeck det. Paraclius zonatus Par. [RMCA]; 2 males, 3 females, Angola (A2): Rocadas, R. Cunene, 19-22.II.1972 / at light / Southern African Exp. B.M. 1972-1; 5 males, 6 females, S.W. Africa (W37), Otjitambi Fm., 27 mls ESE Kamanjab, 13-15.II.1972 / Southern African Exp. B.M. 1972-1; 4 males, S.W. Africa (W52): Swakop R., 3 mls. S. Okahandja, 7.IV.1972 / Southern African Exp. B.M. 1972-1; 4 males, 3 females, Botswana (B21), R. Nata, 20°12'S, 26°11'E, 23.IV.1972 / Southern African Exp. B.M. 1972-1; 1 male, 1 female, Botswana (B18), 25 mls. W Gweta, 20°17'S, 24°54'E, 21–22.IV.1972 / at light / Southern African Exp. B.M. 1972-1; 1 male, Pres. by Imp. Inst. Ent. B.M. 1935-576 / N. Nyasa, shore near deep bay, T.B. Davey […]; 3 males, 3 females, S. Africa (S24): C.P., Dwyka R., Merweville-Koup rd., 2.I.1972 / Southern African Exp. B.M. 1972-1; 1 male, 1 female, Zanzibar, 1.II.1925, R.J. Snell / Pres. by Imp. Inst. Ent. Brit. Mus. 1932-335; 1 male, Angola (A11): Bruco, 26.II-2.III.1972 / Southern African Exp. B.M. 1972-1; 1 male, 1 female, Swaziland, Mbulusane River, 28.III.1984, P. Kelly and J. Cory [NHML]; 3 females, S.W. Africa (30), Armeib Farm, 19 mls NW Karibib; 31.I-2.II.1972 / Southern African Exp. B.M. 1972-1; 1 female, S. Africa (15), Olifants River, 3 mls W Clanwilliam; 6.I.1972 / Southern African Exp. B.M. 1972-1; 1 female, S. Africa: Skukuza, Kruger Nat. Pk., 23.XI.1973 [NHML]; 2 females, S. Africa (S19), R. Mogalakwena, 23°26'S, 28°37'E, 26.IV.1972 / Southern African Exp. B.M. 1972-1; 2 females, Angola (A32): Cachoeiras, 20 mls. SW Gabela, 18-19.III.1972 / Southern African Exp. B.M. 1972-1; 1 female, Gambia: Bakau at Tropic Bungalow, swept in meadow rich in flowers, at the beach, 4.XI.1977, UTM 28PCK1790, Loc. 25 / Lund Univ., Syst. Dept., Sweden Gambia/Senegal. Nov. 1977, Cederholm - Danielsson - Hammarstedt - Hedquist – Samuelsson; 5 males, Congo Belge, Tang, emb. Lubuy U.V., 19.VIII.1953, 5019 [RINS]; 3 males, 4 females, Urundi, Usambura, 10-IV-1953, F. Francois / R. I. Sc. N. B. I.G. 24.452 (2 females with additional label: Colline Usumbura, Imbo, alt. 780 m) [RINS].

Diagnosis. T. tessellatus is characterised by the following features. Scape and pedicel yellow. 1st flagellomere mostly black. Costa thickened in 2nd part. M1+2 with angular curvation before the middle of distal part. All coxae black. Legs simple, mostly yellow; hind tibia black at apex; hind tarsus entirely black. Fore tibia and tarsus with ventral pile of short yellow hairs. Middle tibia with 4 antero-, 3 posterodorsal, 3 antero- and 3 posteroventral setae. Cercus dark-brown, rounded-oval, with long hairs, especially long ventrally.

Remark. Redescription of female T. indirectus by Parent (1934) as well as description of female T. capensis by Curran (1924) does not differ from the species concept of T. tessellatus. A male from the RMCA collection, determined by Curran as T. capensis, is apparently T. tessellatus. In addition, it is important, Curran has never mentioned the latter species in his papers. So, I place T. indirectus and T. capensis in synonymy to T. tessellatus.

Distribution: Senegal; Gambia (!), Nigeria, Congo (Kinshasa), Burundi (!), Tanzania, Aldabra, Ethiopia, South Africa (!), Swaziland (!), Malawi, Angola (!), Namibia (!), Botswana (!), Mozambique, Madagascar, Mauritius, Seychelles, Egypt; Oriental Region, New Caledonia.
 
 

Key to Afrotropical species of Tachytrechus

1. Antenna entirely black ..................... 2

--Antenna partly yellow-brownish ................... 6

2. Legs entirely black, at most knees light ........................... 3

--Legs largely light .................. 5

3. Female (?and male) fore femora and tibia with ventral row of very long setae: femora with 6 and tibia with 5 setae ................... insolitus Parent

--Fore femora without long setae; fore tibia with at most 2 long posteroventral setae ............. 4

4. Male cercus rounded .................. petraeus Loew

--Male cercus subtriangular .................. imperator Curran

5. Femora black in basal half .................. bracteatus Wiedemann

--Femora entirely yellow .................. obscoenus Wiedemann

6. Fore tibia flattened and enlarged (males) .................. 7

-Fore tibia simple or slightly thickened at apex .................. 8

7. Fore tibia flattened in the middle; 1st and 2nd segments of middle tarsus strongly enlarged and flattened; femora partly black .................. pteropodus Schiner

--Fore tibia flattened in apical third; middle tarsus simple .................. elegans Parent

8. Fore basitarsus remarkably slender (males) .................. 9

-- Fore basitarsus not remarkably slender .................. 10

9. Fore basitarsus as long as 2nd to 5th tarsomeres combined ................... consobrinus Walker

- Fore basitarsus twice longer than 2nd-5th tarsomeres (North Africa) .................. insignis Stannius

10. Costa thickened in basal section (males) .................. 11

--Costa simple .................. 15

11. Antenna entirely yellow; fore coxa yellow .................. luteicoxa Parent

-1st flagellomere mostly black; all coxae dark .................. 12

12. Male 1st to 5th tarsomeres of fore tarsus enlarged; cercus yellow, subtriangular .................. planitarsis Becker

- Fore tarsus at most slightly thickened; cercus black, usually oval .................. 13

13. Fore femur mostly black; other femora and tibiae partly blackish; wing maculated at m-cu at M1+2 curvation; cercus black, subtriangular ..................... kenyensis Parent

--Legs mostly yellow, at most femora black at base .................... 14

14. Femora entirely yellow; antennal scape and pedicel yellow; M1+2 with angular curvation ..................... tessellatus Macquart

--Femora black at base; pedicel black, only scape mostly yellow; M1+2 straight ..................... brittoni sp.n.

15. All coxae black; M1+2 curved before the middle of apical part ..................... 16

--Fore coxa yellow; middle and hind coxae mostly brown; legs yellow; postocular setae white; hind femora thick (female) ......................... luteicoxa Parent

16. Antenna entirely yellow ............ melanolepis Bezzi

--1st flagellomere black ..................... 17

17. Propleuron with black setae and hairs ........................ 18

-- Propleuron with yellow hairs and black seta; M1+2 with angular curvation in apical part (females) ..................... 20

18. M1+2 almost straight in apical part, gently curved towards R4+5 ..................... 19

--M1+2 with angular curvation in apical part (female) ..................... pteropodus Schiner

19. Femora entirely yellow; hind tibia black at apex; scape and pedicel yellow ..................... alternatus Curran

-- Fore femur black in basal fourth; middle and hind femora black at extreme base; hind tibia entirely yellow; scape mostly yellow, pedicel black (female) ..................... brittoni sp.n.

20. Middle tibia with 3 antero- and 3 posteroventral setae ..................... tessellatus Macquart

-- Middle tibia with 2 ventral setae ..................... planitarsis Becker
 
 

Acknowledgements

I express sincere gratitude to Dr. Patrick Grootaert, Dr. Marc De Meyer, Dr. Roy Danielsson and Dr. Brian Pitkin for their kindness in furnishing an opportunity to study the collections of the Royal Institute for Natural Sciences (Brussels), the Royal Museum for Central Africa (Tervuren, Belgium), Lund University (Sweden) and the Natural History Museum (London).

References

Becker Th. 1921. Dipterologische Studien: Dolichopodidae. B. Nearktische und Neotropische Region. Abh. Zool.-Bot. Ges. Wien, 13, 1: 1--396.

Becker Th. 1923. Dipterologische Studien: Dolichopodidae. D. Aethiopische Region. Entomol. Mitteilungen, 12, 1: 1--50.

Bezzi M. 1905 (1906). Ditteri Eritrei raccolti dal Dott. Andreini e dal Prof. Tellini. Parte prima. Diptera Orthorrhapha. Bull. Soc. ent. ital., 37: 195--304.

Curran C.H. 1929. New Dolichopodidae from Liberia and the Belgian Congo. Amer. Mus. Novit., 391: 1--10.

Dyte C.E. & Smith K.G. 1980. Family Dolichopodidae. In R.W. Crosskey (ed.). Catalogue of the Diptera of the Afrotropical Region. Brit. Mus. (Nat. Hist.), London: 443--463.

Loew H. 1860. Die Dipteren-Fauna Sudafricas. Erste Abteilung. Abh. Naturw. Ver. Sachs. Thur. Halle, 2: 57--402.

Parent O. 1929. Les Dolichopodides de la Region Ethiopienne. Etude Systematique. Bull. Soc. Roy. Entomol. d'Egypte, 13, 4: 151--190.

Parent O. 1930. Especes nouvelles de Dolichopodides (Dipteres) conserves au Museum National d’Histoire Naturelle de Paris. Ann. Soc. sci. Bruxelles, Ser. B, 50: 86--115.

Parent O. 1934. Etude sur les types de Dolichopodides exotiques de Francis Walker, conserves au British Museum. Ann. Mag. nat. Hist., Ser. 10, 13: 1--38.

Schiner J.R. 1868. Diptera. In: B. von Wullerstorf-Urbair. Reise der osterreichischen Fregatte Novara. Wien, Zool., 2, 1, B: 1--388.

Stackelberg A.A. 1941. Dolichopodidae. In: E. Lindner, ed. Die Fliegen der Palaearktischen Region. Stuttgart, IV, 5, 29, 138: 177--224.
 
 

[Remark under figure]

Fig. 1. Tachytrechus brittoni sp.n. Hypopygium, lateral view.