Syngenes longicornis ( Rambur, 1842 )

Mansell, Mervyn W., 2018, Antlions of southern Africa: Syngenes Kolbe, 1897, with descriptions of two new species and comments on extra-limital taxa (Neuroptera: Myrmeleontidae: Acanthaclisini), Zootaxa 4497 (3), pp. 346-380 : 348-355

Syngenes longicornis ( Rambur, 1842)

Figs 1–24 , 66 , 69 , 72 .

Acanthaclisis longicornis Rambur, 1842: 382 . 5314.

Myrmeleon longicornis (Rambur) : Walker 1853: 320. 6194.

Syngenes longicornis (Rambur) : van der Weele 1907: 266. 406.

Syngenes carfii Insom & Terzani, 2017: 55 . 16257. Syn. nov.

Redescription. Based on Holotype ♀, 10 ♂ and 27 ♀.

Diagnosis. Medium-sized yellow and black antlions. Antennae long, clavate, narrowly annulated with black and yellow. Abdomen with characteristic chevron-like pattern ( Fig. 11 ). Wings broad, with posterior margins of forewings slightly undulating, alternating pale and light brown markings on wing veins, usually with a faint curved mark in distal region of forewing, occasionally with one or two large spots at posterior margin of forewing ( Fig. 1 ). Forewing with characteristic irregular biaereolate cells or bifurcate crossveins in costal area, biaereolate cells extending from before Rs to pterostigma ( Fig. 3 ). Distinguished from other Syngenes species by the right-angular tibial spurs bearing a prominent triangular flange on inner surface ( Figs 4, 5 ), and by the characteristic abdominal pattern.

Head: wider than prothorax, vertex slightly raised, rounded. Frons and vertex black with two large laterally elongated embossed orange patches on vertex, two smaller spots in between, vertex also with row of small, embossed yellow marks, occiput with three large embossed yellow patches. Frons and vertex with short white recumbent setae. Face below antennae, clypeus, genae, labrum uniformly yellow, with long, sparse, pale setae. Antennae long, clavate, longer than twice head width, toruli less than scape diameter apart, scape almost touching eyes, scape and pedicel uniformly yellow, with sparse long white setae, flagellomeres short, annulated with black and yellow, covered in short black setae. Eyes large, greater than hemispherical, with sparse ocular setae usually present. Maxillary and labial palps very small, much less than head width, yellow, terminal labial palpomere spindle-shaped with long acute apex, palpimacula short, slit-shaped ( Fig. 6 ).

Thorax: yellow with black markings, sparsely pilose. Pronotum longer than wide, tapering anteriorly. Anterior margin with two curved black lines laterally merging anteriorly, sides of pronotum with two diffuse black streaks, another two oblique streaks on each side of midline at posterior margin, central pronotum with distinct dots. Sparse long white and black forwardly curved setae situated laterally, short black bristles present along anterior raised margin, posterior margin with long curved black setae. Mesothorax: mesoprescutum yellow, brown anteriorly, a large diffuse black mark on either side of midline, anterior margin with long curved black setae; mesoscutum yellow with four longitudinal black lines on either side above wing bases and sparse black setae; mesoscutellum yellow with two black central stripes and two larger diffuse black spots posterior to central stripes. Metathorax: metaprescutum yellow with two large black marks on either side, metanotum with two velvety spots on each side, two longitudinal stripes laterally above wing bases, long curved white setae laterally; metascutum yellow with a large black mark on either side of midline, devoid of setae. Pleurites below wings yellow with irregular brown marks, sternites yellow, dense long white setae present on pleurites and sternites.

Wings: broad, forewings longer, broader than hind wings, apices sub-acute, membrane hyaline, veins with alternating sections of yellow and black, bearing very short sparse black and yellow setae on correspondingly coloured areas. Forewings broad with slightly undulating posterior margin, apices rounded with sub-acute tip, usually with a faint curved mark in distal part, occasionally with one or two spots at posterior margin. Axillary protuberance at base of forewing yellow with long dense white and black setae. Costa alternating yellow and black with tuft of short black bristles at base, costal area narrow at base, broadening distally; costal veins irregular, usually 7 cells (but variable) before Rs, some veins bifurcate, with biaereolate cells in unbroken series extending distally from Rs. Pterostigma pale yellow, indistinct. Apical margin of wing with densely arranged narrowly-forked veins. Hypostigmatic cell elongate. Sc, R and proximal region of CuA with yellow and black chevron-like pattern. Rs arises well beyond CuA fork; area between Sc and R mostly pale with black cross-markings; 8–10 presectoral veins present. Mp2 (oblique crossvein) arising beyond CuA fork, CuP arises just before basal crossvein, fused with A1, A2 very short (sometimes not manifest, merged with A1 from base), curved before merging with A1. Hind wings narrower than forewings, lanceolate, always unmarked; axillary protuberance at base yellow with long dense white setae, C mainly yellow with tuft of long white recumbent setae at base, costal area narrow at base, broadening then narrowing, uniareolate, veins unbranched. Pterostigma yellow, hardly discernible. Hypostigmatic cell long. 5–6 occasionally 7 presectoral crossveins, Rs arises beyond Mp2 fork, Cu fused with posterior branch of Mp2 fork; anterior banksian line visible in distal portion of wing. Pilula axillaris in males conspicuous with densely packed short brown recumbent setae, females with long white setae in this position.

Legs: forelegs strongly developed with short stout spines. Coxa, trochanter yellow with long white pubescence. Femur yellow with faint diffuse brown marks, very stout, thickened at base tapering distally, two femoral sense hairs near base, ventral surface with two rows of strong short black spines accommodating tibia on closure, long white setae with occasional black setae present. Tibia slender, yellow with four black stripes at femoral articulation and two black annulations proximally, one distally; lateral surfaces with long white setae, black setae dorsally, with dense pad of short black setae ventrally fitting between the two rows of black bristles on femur. A dense facial brush of short golden pubescence present on interior apical surface ( Fig. 4 ). Tibial spurs ( Figs 4, 5 ) characteristically bent at a right angle with prominent triangular flange. Tarsus with Ta5 longer than Ta1–Ta4 combined, Ta1–Ta4 yellow with black annulation on each, covered in short black bristles, Ta5 long, yellow, black apically, covered with short black bristles; preapical claws dark reddish-brown, stout, strongly curved. Middle legs shorter, more slender than forelegs, entirely yellow; coxa, trochanter shorter than in foreleg, with long white pubescence. Femur yellow with one sensory seta proximally, two rows of black bristles ventrally as in foreleg, covered with long white setae and sparse patch of long black bristles dorso-apically. Tibia, tarsus as in forelegs, but without facial brush. Hind legs long slender, yellow, lacking femoral sense hair; coxa, trochanter as in middle leg, femur sometimes with small black dots at setal bases, dorsal surface with short black setae, laterally with long black curved setae, long white setae proximally, ventral surface with two rows of short black bristles; tibia, tarsus as in middle leg.

Abdomen: yellow with characteristic black markings imparting a chevron-like pattern ( Fig. 11 ), tergites with sparse short black setae, sternites yellow with sparse short white setae but sternites 1–2 with long soft dense white pubescence. T1 yellow, black centrally, T2 yellow laterally black centrally, T3 yellow with black mark on either side of midline tapering to two parallel stripes anteriorly. Male ( Figs 7–10 , 13–16 ): T9 yellow, divided dorsally, two black streaks along posterior margins. IX brown, short, rounded with pale central stripe and fringe of long black posteriorly directed setae. Ectoprocts yellow, very long, anterior dorsal margin with 2 black streaks and long anteriorly-curved white and black setae becoming much longer posteriorly, base of ectoprocts swollen bearing a dense tuft of short black setae. Gonarcus ( Figs 13–16 ) bears a prominent beak-shaped Mu; Pa ( Figs 13–16 ) sclerotized, articulating with Gs, terminating in upwardly curved sharply pointed extremities. Female ( Figs 17–20 ): T9 divided dorsally, Ga digitiform with long white setae, Gl clavate bearing long stout, slightly curved pale spines, Epr rounded, bearing slender, slightly curved setae. Spermatheca ( Fig. 20 ) broad proximally becoming slender and coiled, tapering distally, with fine setae along distal extremity.

Larva ( Fig. 12 ). Described by Stange & Miller (1985), who provided notes on the habitat and behavior. It is a beautiful black and white larva that is fast moving and free-living in coastal dunes on the fringes of vegetation along the eastern seaboard of Africa.

Distribution ( Fig. 72 ). Extending along the eastern coastal belt from the Western Cape Province, South Africa to Mozambique and into Tanzania and Somalia.

Comments. The first Syngenes species to be described, S. longicornis (as Acanthaclisis ) ( Rambur 1842) has been misinterpreted by most previous authors: van der Weele (1907, 1908), Esben-Petersen (1916, 1920), Banks (1920), Navás (1924, 1935), Fraser (1951), Handschin (1963), Ohm & Hölzel (1995), Insom & Terzani (2017). The correct identification of this taxon was consequently crucial to determining the subsequent species described from the Afrotropical Region. Rambur (1842) specifically stated that the country of origin was unknown, but there is now a label attached to the type specimen indicating “ Senegal ” ( Fig. 23 ). This is clearly an erroneous subsequent addition ( Prost 1998), who also stated that S. longicornis is a southern African taxon that does not occur in West Africa, an assumption verified here. This name however, still required association with a known population of Syngenes to understand its characteristics and extent. This relationship has now been clearly associated with a species that occurs in coastal forests and verges of dune vegetation along the east coast of Africa. It does not extend far inland, unless ideal sandy conditions exist (e.g. Tembe Elephant Reserve, South Africa). This species, with its characteristic white larvae ( Fig. 12 ), has been uncritically, but correctly, identified as S. longicornis by recent authors: Stange & Miller (1985), Gess & Gess (1998). A characteristic of S. longicornis is that the tibial spurs are sharply bent at a right angle and there is a prominent triangular flange along the ventral surface ( Figs 4, 5 ). This is also the typical spur structure of the genus Centroclisis , but is not as pronounced in other species of Syngenes . Furthermore, biaereolate cells are present in the forewing costal area from before Rs ( Fig. 3 ). There are other features, including a chevron-like (inverted V-shape) abdominal pattern ( Fig. 11 ) that characterize this species. Examination of the female holotype of Acanthaclisis longicornis in IRSN, and from photographs provided by Jerome Constant (IRSN) ( Figs 21–24 ), has confirmed the tibial spur structure ( Fig. 22 ), and features of the wings and abdomen closely match that of the southern and eastern African population, which is now confirmed as S. longicornis . It consequently does not occur in the other countries listed by Stange (2004): Benin, Madagascar, Senegal, Seychelles and Togo.

The specimen illustrated by van der Weele (1907, Pl. 9, Fig. 9 ) is not S. longicornis , as already stated by Navás (1912), but is clearly S. maritimus .

Syngenes carfii Insom & Terzani, 2017 , shares all the main characters for distinguishing S. longicornis : tibial spurs right-angled with internal flange, chevron-like abdominal pattern and the forewing costal area with biaereolate cells before Rs. It is consequently relegated to synonymy with S. longicornis .

Type material examined. Holotype ♀ and photographs: no associated locality data, collector or date (IRSN)

( Figs 21–24 ).

Additional material examined. SOUTH AFRICA , Western Cape Province: 1♀, Wilderness , 33°59’S 22°35’E, 24.ii.1965, J.S.Taylor, ZILS00114 ( ZILS) ; 1♀, Still Bay 34°22’17”S 21°24’32”E, 40m, 15.ii.1971, D.J.van Wyk, NEUR11835 . Eastern Cape Province: 1♂ 1♀, Kenton on Sea , 33°40’S 26°40’E, 50m, 15.ii.1971, R.A.Jubb, Malaise trap, NEUR11829 ; 1♀, Kleinemonde , 33°32’29”S 27°02’54”E, 20m, 17.ii.1971, M.W.Mansell, NEUR11836 ; 1♂, St Francis Bay, 34°10’S 24°50’E, 20m, 12.iii.1972, M.W.Mansell, NEUR09458 ; 4♂ 2♀, Port Alfred , 33°36’S 26°54’E, 20m, 15.xii.1988, E.Grobbelaar, NEUR11842 . KwaZulu-Natal: 1♀, Lake Sibaya , 27°22’04”S 32°42’56”E, 50m, 7.i.1968, M.W.Mansell, NEUR11834 ; 1♀, same data but 23.i.1970, NEUR11833 ; 1♀, Cape Vidal, 28°07’24”S 32°33’23”E, 30m, 10.xii.1973, L.R.Minter, NEUR11156 ; 1♂, Umlalazi Nature Reserve , 28°57’S 31°45’E, 10m, 28.i.1988, J.G.H.Londt, NEUR11837 ; 3♀, Sodwana Bay, 27°32’S 32°41’E, 30m, 3.xii.1988, H.Terblanche, NEUR01956 ; 2♀, same locality, 8.ii.1997, R.G.Oberprieler, NEUR10145 ; 2♀, Kosi Bay Nature Reserve, 26°59’S 3°48’E, 10m, 8.ii.1990, E.Grobbelaar, NEUR01584 ; 1♀, Kuleni Farm , 27°54’43”S 32°21’52”E, 115m, 12.ii.1990, E.Grobbelaar, NEUR01612 ; 1♀, Sihangwana, Tembe Elephant Park, 27°02’30”S 32°25’20”E, 85m, 1.ii.1996, R.Stals, NEUR11828; 1♀, same data but 6.iv.1996, NEUR05699 ; 1♂ 1♀, same locality, 1.ii.1996, E.Grobbelaar, NEUR05595 ; 4♀, same data but 25.i.2006, NEUR09438 ; 1♀, St Lucia Lake , 28°23’S 32°24’E, 20m, 11.ii.1997, R.G.Oberprieler, NEUR10144 ; 1♀, Ndumu Game Reserve , 26°51’60”S 32°15’00”E, 45m, 27.i.2006, E.Grobbelaar, NEUR09433 ; 1♀, Maphelana , 28°23’53”S 32°24’59”E, 29.i. 1993, 6m, J.deG. Harrison, TMSA00885 ( TMSA) .

MOZAMBIQUE: 1♂, Inhaca Island , 26°02’19”S 32°54’14”E, 10m, 23.i.1971, M.W.Mansell, NEUR11830 ; 1♀, Beira 20 km N, 19°45’22”S 35°01’28”E, 5m, 3.iv.2000, R.D.Stephen, NEUR05587 ; 1♂ 1♀, Chidenguele , 24°56’03”S 34°11’09”E, 18m, 27.ii.2016, A.J.Gardiner, NEUR12539 .

Figures

FIGURE 72. Recorded distribution of Syngenes species in southern Africa. Map: C. Deschodt.

FIGURES 1–2. Syngenes longicornis (Rambur). 1, male habitus NEUR11837 (forewing length 42 mm); 2, female habitus NEUR11833 (forewing length 42 mm), showing wing pattern variation.

FIGURES 3–6. Syngenes longicornis. 3, base of forewing showing main veins and biaereolate cells in subcostal area; 4, foreleg tibial spurs with flange and facial brush; 5, hind leg tibial spurs with flange; 6, labial palp with palpimacula. Abbreviations: A1 = First anal vein, C = Costal vein, CuA = Anterior cubital vein, CuP = Posterior cubital vein, Cc = Costal cell, Mp2 = branch of posterior medial vein (oblique vein), R = radial vein, Rs = Radial sector, Rs2 = second radial sector, Sc = Subcostal vein.

FIGURES 7–9. Syngenes longicornis 7, male terminalia lateral; 8, dorsal; 9, ventral. Abbreviation: T9, Tergite 9.

FIGURES 10–12. Syngenes longicornis. 10, abdomen dorsal with hair pencil details; 11, abdomen dorsal showing pattern; 12, third instar larva, photo: H. de Klerk©.

FIGURES 13–16. Syngenes longicornis. Male gonarcus and parameres complex: 13, lateral; 14, dorsal; 15, caudal; 16, ventral. Abbreviations: Gs = Gonarcus, Mu = Mediuncus, Pa = Paramere.

FIGURES 17–20. Syngenes longicornis. Female Terminalia: 17, lateral; 18, ventral; 19, dorsal; 20, spermatheca. Abbreviations: Ga = anterior gonapophyses, Gl = lateral gonapophyses, Epr = Ectoproct, T9 = Tergite 9.

FIGURES 21–24. Acanthaclisis longicornis Rambur, (Syngenes longicornis). Holotype female (IRSN): 21, habitus; 22, tibial spur; 23, associated labels; 24, forewing showing details of subcostal cells. Photographs: J. Constant (IRSN).

FIGURES 66–68. Syngenes species. Comparative lateral gonarcus and parameres complex: 66, S. longicornis; 67, S. scholtzi; 68, S. medialis.

FIGURES 69–71. Syngenes species. Comparative wing venation of Holotypes: 69, S. longicornis; 70, S. medialis; 71, S. scholtzi.