Congomochtherus inachus Londt & Tsacas, 1987

Jason G. H. Londt, 2014, The Afrotropical Robber Fly Genus Congomochtherus Oldroyd, 1979 (Diptera: Asilidae: Asilinae), African Invertebrates 55 (2), pp. 333-350 : 338-340

Congomochtherus inachus Londt & Tsacas, 1987

Figs 3 , 4 , 7 , 17

Congomochtherus inachus Londt & Tsacas, 1987: 33 (figs 3 postmetacoxal area, 19-24 ♂ terminalia, 25 ♀ terminalia).

Previously recorded material: Londt & Tsacas (1987) listed the following type material: SOUTH AFRICA: 1♀ (paratype), Cacudu River nr. Lady Frere, 3127CA, [c. 31°42'S 27°14'E, c. 1015 m], 27.x.1978, Londt & Miller, river bank (NMSA); 1♀ (paratype), Doringbos on Doring River, 3119CC, 500 ft, [c. 31°58'S 19°13'E, c. 170 m], 14.ix.1972, Irwin, riverbank sand dunes (NMSA); 1♀ (paratype), Olifantsrivier between Klawer & Clanwilliam, 3118DC [c. 31°59'S 18°45'E, c. 1020 m] (SAMC); 1♂ (paratype), Heuningklip River, 25 km W Queenstown, 3126DC, [c. 31°55'S 26°40'E, c. 1140 m], 27.x.1978, Miller & Londt, river bank (NMSA); 1♀ (paratype), 32 km NE Clanwilliam, 3219AA, [c. 32°04'S 19°04'E, c. 310 m], 2-13.x.1977, Miller, Brandewyn River (NMSA); 7♂ (holotype & paratypes) 4♀ (paratypes), Cradock, Fish River, 3225BA, [c. 32°10'S 25°37'E, c. 875 m], 28.x.1978, Londt & Miller, river bank (NMSA (HT 4♂ 2♀ paratypes)*, MNHN, BMNH); 6♂ 3♀ (paratypes), Klein-Vis Riv., 32 km NW Somerset East, 3225CB, [c. 32°30'S 25°26'E, c. 1040 m], 28.x.1978, Miller & Londt, river banks (NMSA); 4♂ 6♀ (paratypes), Klein-Vis Riv., 8 km W Somerset East, 3225CB, [c. 32°42'S 25°28'E, c. 810 m], 29.x.1978, Miller & Londt, river bank (NMSA); 1♂ (paratype), 1 km NW Somerset East, 3225DA, [c. 32°43'S 25°35'E, c. 805 m], 28-29.x.1978, Londt & Miller, picnic area stream (NMSA); 3♂ (paratypes), nr. Fullarton Station, Groot River, 3323BB, [c. 33°10'S 23°50'E, c. 595 m], 30.x.1978, Miller & Londt, river bank (NMSA); 2♂ 2♀ (paratypes), 7 km N Steytlerville, Groot River, 3324AB, [c. 33°15'S 24°23'E, c. 510 m], 30.x.1978, Londt & Miller, river bank & Field (NMSA).

Newly recorded material: SOUTH AFRICA: 1♂, same data as holotype (NMSA); 1♂ 1♀, nr. Fullarton Station [as above] (NMSA); 4♂, 7 km NE Nieu Bethesda, 31°51'S 2 4°36'E, 1410 m, 11.x.1996, Londt, streamside rocks bush (NMSA); 2♂ 4♀, Nieu Bethesda village, 31°52'S 24°33'E, 1290 m, 11.x.1996, Londt, bush along dry river (NMSA); 14♂ 2♀, c. 2 km NE of Middelpos, 31°53'34"S 20°14'14"E, 1130 m, 17.xi.2011, Londt, Karoo scrub area and dam margins (NMSA); 2♂, c. 8 km SW of Middelpos, 31°57'07"S 20°11'11"E, 1175 m, 17.xi.2011, Londt, Karoo scrub area and dam margins (NMSA); 2♂, Renoster River area 18 km N of Sutherland, 32°15'10"S 20°41'39"E, 1290 m, 7.xi.1998, Londt, Karoo macchia (NMSA); 3♂ 1♀, Renoster River 18 km N Sutherland, 32°15.21'S 20°41.67'E, 1320 m, 19-20.xi.2008, Londt, rocky ridge stream edge (NMSA); 2♂ 1♀, 18 km N of Sutherland, 32°16'S 20°41'E, 1350 m, 26.xi.1990, Londt & Whittington, Renosterrivier area (NMSA); 2♂, 35 km NE of Sutherland, 32°18'S 20°00'E, 1300 m, 27.xi.1990, Londt & Whittington, Rietriver bridge area (NMSA); 2♂, 18 km S of Sutherland, 32°32'16"S 20°37'09"E, 1390 m, 3-24.x.2004, Irwin, Parker & Hauser, Malaise in steep damp wash (NMSA); 1♂, 10 km S of Citrusdal, Koornlandskloof, 32°40'S 19°02'E, [c. 170 m], 5-9.x.1994, Söderlund, Malaise-trap, among shrubs at riverside (NMSA); 3♂ 7♀, Klein Visrivier, c. 10 km W Somerset East, 32°44'S 25°30'E, 800 m, 6.xii.1989, Londt, rocky ridge & stream (NMSA); 1♂ 5♀, Dwyka River N1, 33°05'07"S 21°34'46"E, 455m, 13.x.2013, Londt, rocky river-bed with stagnant pools (NMSA); 3♂ 2♀, 5 km S of Laingsburg, 33°14'S 20°52'E, 700 m, 25.xi.1990, Londt & Whittington, banks Buffels River (NMSA); 3♂ 1♀, Meiringspoort area, Opmetings Drif, 33°21'14"S 22°32'36"E, 712 m, 14.x.2013, Londt, stony river margin (NMSA); 3♂, Meiringspoort area, Pereboom Drif, 33°22'02"S 22°33'15"E, 6 75 m, 14.x.2013, Londt, stony river margin (NMSA); 2♂ 1♀, 17 km N of De Rust, 33°22'S 22°33'E, 700 m, 23.xi.1990, Londt & Whittington, Meiringspoort area (NMSA).

Distribution ( Fig. 17 ), phenology ( Table 1 ) and biology:A South African endemic found in the Eastern Cape, Western Cape and Northern Cape provinces. This is the species that I am most familiar with as I have collected specimens on no fewer than 22 occasions. Like elferinki this species is encountered on rocks in rivers and streams. It was this species that first alerted me to this fairly unique behaviour amongst the Asilinae. So intrigued was I that I sent specimens and photos to Dr Léonidas Tsacas, then active at the Muséum national d'Histoire naturelle, Paris, asking for his taxonomic opinion. His input eventually resulted in a joint publication ( Londt & Tsacas 1987). This species has been collected during every month between September and December ( Table 1 ). It is, however, likely to be active for the entire summer, although in the Western Cape, which lies in a region of winter rainfall, streams and dams may be low and this fact could curtail the species' activity. Little biological information is available.Apart from the flies behaving essentially like elferinki (see above), it also transpires that flies of both sexes will also come to rest along the muddy margins of largely dry river beds (such as the Dwyka River pictured in Fig. 3 ) or along the edges of dams where rocks are not available (such as the Middlepos dam pictured in Fig. 4 ). This is the only species for which there are prey records. 1♂ and 1♀ from the Klein Visrivier were captured while feeding on adult Empididae (NMSA prey records 0793 & 0974). These empids commonly fly over water surfaces and are therefore easily accessible prey.

Figures

Fig. 4. Congomochtherus inachus Londt & Tsacas, 1987, habitat (2 km NE of Middelpos, dam margins).

Fig. 17. Southern African distribution of Congomochtherus Oldroyd 1979: C. acuminatus Oldroyd, 1974 (circles); C. elferinki Londt & Tsacas, 1987 (squares); C. inachus Londt & Tsacas, 1987 (triangles); C. potamius Londt & Tsacas, 1987 (diamond).

Fig.3. Congomochtherus inachus Londt & Tsacas,1987, habitat (Dwyka River at bridge where N1 crosses, rocky river bed with stagnant pools).

Figs 5-11.Congomochtherus ♂ terminalia (lateral):(5) C. acuminatus Oldroyd, 1974; (6) C. elferinki Londt & Tsacas, 1987; (7) C. inachus Londt & Tsacas, 1987; (8) C. lobatus Oldroyd, 1970; (9) C. oldroydi Londt & Tsacas, 1987; (10) C. penicillatus (Speiser, 1910); (11) C. potamius Londt & Tsacas, 1987 (Scale bars = 1 mm).