Neotherevella arenaria (Lyneborg)

Winterton, Shaun L., Irwin, Michael E. & Mortelmans, Jonas, 2023, Revision of the dune-associated stiletto flies of the genus Neotherevella Lyneborg, 1978 (Therevidae, Therevinae), African Invertebrates 64 (2), pp. 109-138 : 109

Neotherevella arenaria (Lyneborg)

Figs 1 , 2 , 3 , 11C, D , 12A, B , 13A, B , 14B , 15

Neothereva arenaria Lyneborg, 1976: 293.

Neotherevella arenaria (Lyneborg, 1976)- Lyneborg (1978: 76 [combination change], 1980: 319 [catalogue]); Hauser et al. (2017: 1200 [faunal synopsis, wing figure]).

Holotype.

Namibia • male; Erongo Region, Swakopmund; 26-30 Jan 1972; NHM.

Other material.

Namibia • 8 males, 7 females; Erongo Region, Swakopmund, Swakop River mouth; [-22.6886, 14.5275]; 8 m alt.; 9 Feb 1974; M.E. & B.J. Irwin leg.; coastal and riverbed dunes; CSCA; MEI028397-400, 120720-23, 120760-1, 178074-8 • 3 males; Erongo Region, Swakopmund, Swakop River mouth; [-22.6925, 14.5269]; 03 Feb 2012; T. Dikow leg.; sandy river bed and vegetated dunes; USNM; USNMENT01576797-9 • 2 males, 1 female; Karas Region; Lüderitz District, Agate Beach , 10 km N Lüderitz; [-26.5949, 15.1792]; 3 m alt.; 18 Feb 1974; M.E. & B.J. Irwin leg.; low coastal vegetated dunes; CSCA; MEI120715, 178075-6 .

Diagnosis.

Male frons lacking dark maculae; female frontal maculae with short pile of erect macrosetae; male eyes contiguous below ocellar tubercle; wing cell m3 closed; all macrosetae black; single pair (sometimes two) of dorsocentral macrosetae; palpus slender.

Redescription.

Body length: 6.0-6.5 mm (male), 7.0-7.5 mm (female). Head. Frons profile flat, wholly pubescent; male frons narrower than anterior ocellus, but eyes not contiguous, female frons broad with eyes slightly narrowed dorsally; frontal pubescence silver with dark yellow suffusion, female with paired matte-black maculae admixed with short, erect, black setae; male frons with small patch of short setae above antenna, female sparse short setae, frontal setae admixed black and yellow; postocular setae black, arranged in single row immediately laterad of ocellar tubercle (male), additional setae irregularly arranged medially (female); occiput relatively flat, silver pubescence admixed with white, scale-like setae, more abundant medially; genal setae pale, palpus narrow, covered with pale setae; antennal scape shorter than flagellum, slightly thickened and cylindrical, brown, overlain with grey pubescence admixed with erect black setae of varying lengths; flagellum conical, brown with grey pubescence. Thorax. Scutum grey-tan with brown markings, short erect filiform setae admixed with adpressed white scale-like setae, denser anteriorly; macrosetae black; scutellum concolourous with scutum; pleuron with dense silver-grey pubescence admixed with extensive semi-erect, white, scale-like setae; anepisternum with brownish suffusion dorsally; coxae with pale macrosetae admixed with erect white, scale-like setae; femora with dense covering of white, scale-like, adpressed setae (sparser in female); legs dark yellow, macrosetae black; hind femur with 3-4 anteroventral macrosetae distributed along distal half; tarsi dark yellow with apices brown; tibial and tarsal macrosetae elongate; wing white with irregular-sized brown maculae (darker in female), spur veins often present in maculae; cell m3 closed; wing venation yellow basally along major veins, darker distally; haltere dark yellow; scutal chaetotaxy (macrosetae pairs): notopleural, 3; supra alar, 1-2; post alar, 1; dorsocentral, 1-2; scutellar, 2. Abdomen. Male base colour yellow, grey pubescent, filiform setae admixed with adpressed setae, very dense in male; terminalia dark yellow; female abdomen dark yellow; acanthophorite spines black. Male genitalia. Epandrium sub-quadrangular, posterolateral corners thickened, rounded; sternite 8 rounded posteriorly with thickened margin and short series of elongate, marginal macrosetae; gonocoxite with extensive pale setae, outer gonocoxal process relatively narrow, angular; gonocoxal apodeme absent; inner gonocoxal process rounded apically; gonostylus narrow; ventral lobe short, rounded; distiphallus narrow, gradually curved ventrally; ventral apodeme triangular.

Distribution.

Coastal Namibia.

Ecology.

Neotherevella arenaria sp. nov. adults are found in coastal dune systems associated with low vegetation (Fig. 3 ).

Conservation status.

Unknown; this species is apparently locally abundant in relatively undisturbed habitats.

Comments.

Neotherevella arenaria sp. nov. is closely related to N. londti sp. nov. and represents a species pair sharing characters not found in other Neotherevella species, including erect macrosetae on the frontal maculae, black thoracic macrosetae (pale in other species) and distinct dorsocentral macrosetae (absent or indistinct in other species). These two species are found in south-western Africa, relatively disparately distributed from other Neotherevella species, which are found throughout the southern Palaearctic Region.

Figures

Figure 1. Neotherevella arenaria (Lyneborg, 1976), female A oblique view B lateral view.

Figure 2. Neotherevella arenaria (Lyneborg, 1976), male A oblique view B lateral view.

Figure 3. Vegetated sand dunes at the Swakop River mouth, Swakopmund (Namibia); habitat of Neotherevella arenaria (photo copyright: Torsten Dikow).

Figure 11. Neotherevella species, head, frontal view A Neotherevella kozlovi (Zaitzev, 1971 a), male B same, female C Neotherevella arenaria (Lyneborg, 1976), male D same, female E Neotherevella londti sp. nov., male F same, female G Neotherevella macularis (Wiedemann, 1828), male H same, female I Neotherevella maroccanus sp. nov., male.

Figure 12. Neotherevella species, male epandrium and sternite 8 A, B Neotherevella arenaria (Lyneborg, 1976) C, D Neotherevella kozlovi (Zaitzev, 1971 a) E, F Neotherevella londti sp. nov. G, H Neotherevella macularis (Wiedemann, 1828). Scale bar: 0.25 mm.

Figure 13. Neotherevella species, male gonocoxites (ventral view left, dorsal view right) with phallus in situ A, B Neotherevella arenaria (Lyneborg, 1976) C, D Neotherevella kozlovi (Zaitzev, 1971) E, F Neotherevella londti sp. nov. G, H Neotherevella macularis (Wiedemann, 1828). Scale bar: 0.25 mm.

Figure 14. Neotherevella species, male phallus A Neotherevella kozlovi (Zaitzev, 1971), lateral view B Neotherevella arenaria (Lyneborg, 1976), lateral view C Neotherevella londti sp. nov., lateral view D Neotherevella macularis (Wiedemann, 1828), lateral view E Neotherevella londti sp. nov., ventral view F Neotherevella macularis (Wiedemann, 1828), dorsal view. Scale bar: 0.25 mm.

Figure 15. Neotherevella distribution.