Diopsis stuckenbergi, Feijen & Feijen, 2012

Feijen, Hans R. & Feijen, Cobi, 2012, A new species of Diopsis L. (Diptera: Diopsidae) from South Africa and Swaziland, and brief review of African species with a large apical wing spot, African Invertebrates 53 (1), pp. 125-125 : 132-137

Diopsis stuckenbergi sp. n.

Figs 2, 4 , 8, 9 , 15, 17, 19 , 23–30

Etymology: This striking species is named after Brian Roy Stuckenberg, who supported the writers’ Diopsidae research in its early stages and who accompanied the second author while she collected most of the type series in 1980.

Diagnosis: The new species can be distinguished by the smooth frons, distinct facial teeth, small IVB (equal to stalk diameter), scutum with fine granulated structure and pruinose T-cross (sometimes centre of cross absent), large apical wing spot extending proximally in cell r 4+5, two whitish wing spots before apical spot, slender front femora, dark front tarsi, brown terga, trapezoid ♀ sternum 7, ♀ tergum 8 a single sclerite, ♀ sternum 8 two longitudinal sclerites, rounded spermathecae with small tubercles, ellipsoid epandrium, non-articulated surstyli in lateral view almost straight and parallel-sided, in posterior view club-shaped, and low sexual dimorphism in eye span (D =1.15, proportion eye span/body length 1.02 in ♀ and 1.30 in ♂).

Description (♂ and ♀):

Measurements: Overall length: ♀ 7.7 mm ± SE 0.1 (range 5.9–9.1, n =69), ♂ 7.3 mm ± 0.1 (range 5.9–8.7, n =52); eye span: ♀ 7.9 mm ± 0.1 (range 5.9–9.5, n =69), ♂ 9.6 mm ± 0.3 (range 6.5–12.8, n =52); wing length: ♀ 6.1 mm ± 0.1 (range 4.9–7.1, n =69), ♂ 5.8 mm ± 0.1 (range 4.7–6.9, n = 51); length of scutellar spine: ♀ 1.56 mm ± 0.02 (range 1.16–1.83, n =70), ♂ 1.51 mm ± 0.02 (range 1.08–1.83, n =51).

Head ( Fig. 2 ): Central part glossy reddish brown; frons smooth, but with a very fine and delicate honeycomb-like pattern, more laterally a system of small ridges running towards facial sulcus; arcuate grove slightly darker; face with very fine horizontal ridges, upper half of face slightly protruding, distinct facial teeth; eye span medium-sized in female (2% longer than length of body) and very large in male (30 % longer than length of body); rate of dimorphism low, D = 1.15 ( Fig. 23 , Table 1); stalks glossy brown, broad apical parts blackish pruinose posteriorly, funiculus uniformly brown, clothed in whitish pruinosity, IVB small, almost equal to diameter of eye stalk, base of IVB a minuscule elevation of about 0.25 diameter of stalk ( Fig. 2 ); OVB small, just longer than diameter of stalk; head with sparse tiny white setulae.

Thorax ( Figs 8, 9 ): Collar glossy black, anterior edge (including central knob) with very narrow line of pruinosity, lateral margins of collar with some pruinosity; humeral calli and lateral sections of scutum smooth, main part of scutum with finely granulated structure ( Fig. 8 ), scutum glossy black with variable pruinosity pattern (compare Figs 8, 9 ), in 56% of specimens scutum with pruinose mesal band on posterior ⅔ that combines with transverse pruinose band forming T-shaped cross, in other specimens heart of cross lacking, resulting in pruinose lateral sections between humeral callus and intrascutal suture and large triangular section anteriorly of scutellum running out mesally in anterior direction until anteriorly of the intrascutal suture, in all Swaziland specimens T-cross present, no difference between ♀ and ♂ in pruinosity pattern (respectively 59% and 54 % with a T-cross); pleura pruinose with large glossy central section; scutellum brown pruinose, scutellar spines glossy brown darkening towards tip; scutellar spines long, strong and straight, 3× as long as scutellum, diverging at an angle of 55–60°; metapleural spines well developed, anterolaterally-directed, somewhat curved; thorax with some fine white setulae, especially on scutellar spines and below wing base.

Wing ( Fig. 4 ): Large apical wing spot in cells r 2+3, r 4+5 and m, irregularly-shaped, extending proximally 2× as far in cell r 4+5 as in cell r 2+3, hardly reaching posterior margin in cell m; between apical wing spot and central infuscation a band of three clear spots separated by infuscation along veins R 4+5 and M, especially two whitish spots in cells r 2+3 and r 4+5 strikingly iridescent without microtrichia at their centre; central infuscation extensive, darkest in basal half of cell r 4+5 and cell dm, along vein R 4+5, vein Cu and crossvein R–M; clothed in microtrichia, except for glabrous centres of white spots and glabrous basal areas, these last mentioned areas include posterior part of cell c, basal tip of cell r 1, basal ⅔ of cell br, cell bm, except for distal and posterior edges, and basal ⅓ of cell cu p.

Legs: Front leg with pale brown coxa, trochanter and femur and dark brown to blackish tibia and tarsi, ventral surface of tibia clothed in dense orange-brown short setulae; mid leg uniformly yellowish brown; hind leg yellowish brown, with dark brown to blackish tibia and longitudinal dark stripe on femur; femur 1 slender in both ♀ and ♂ proportion of length/width: ♀ 6.1 ± 0.0 (range 5.8–6.5, n =20), ♂ 6.4 ± 0.1 (range 5.9–7.2, n =20), two rows of tubercles in distal ½ to ⅓, inner row ♀ with 14.2 ± 0.3 tubercles (range 11–18, n = 40) and ♂ with 13.3 ± 0.3 tubercles (range 10–16, n =40), outer row ♀ with 12.5 ± 0.2 tubercles (range 9–14, n =40) and ♂ with 11.4 ± 0.3 tubercles (range 7–15, n =40); femora 2 and 3 with small apical spur.

Abdomen: Syntergum 1+2+3 glossy brown, basally somewhat darker, with some pruinosity medially, no sutures visible; other terga glossy brown, terga with sparse, fine setulae; ventral preabdomen yellowish and thinly pruinose, sternum 1 slightly darker, more glossy; spiracle 1 in membrane, intersclerite 1–2 very narrow; sterna 4 and 5 single rectangular plates, sternum in ♂ slightly folded inward on the meson.

Female postabdomen ( Figs 17, 19 , 24–27 ): Straight, not deflexed, terga 6, 7 and 8 single rectangular sclerites ( Fig. 24 ); tergum 10 with one pair of long setulae and 1 or 2 pairs of short setulae; cerci rather elongate, proportion of length/width 3.4 ( Fig. 25 ), clothed in microtrichia and some setulae; sternum 6 quadrangular sclerite, sternum 7 trapezoid sclerite more sclerotised laterally and posteriorly; sternum 8 consisting of two longitudinal sclerites ( Fig. 17 ); spiracle 6 just within membrane, spiracle 7 on edge in tergum; subanal plate pentagonal ( Fig. 26 ), posteriorly 4 pairs of setulae; spermathecae ( Fig. 27 ) rounded with number of dispersed diminutive tubercles, inner basal structure well developed; sclerotised ring of ventral vagina wall compact, subelliptical, with very broad lateral arms ( Fig. 19 ).

Male postabdomen ( Figs 15 , 28–30 ): Straight; sternum 6 virtually atrophied, represented by two characteristic anterior microchaetae and 2 vague diminutive sclerites folded inward; synsternum 7+8 extremely narrow, almost line-like, weakly sclerotised, left spiracle 7 in membrane, right spiracle 7 just touching synsternum; epandrium ( Fig. 28 ) elliptical in posterior view, with about 12 pairs of setulae, clothed in microtrichia; surstyli non-articulated, seamlessly fused to epandrium, in lateral view ( Fig. 15 ) virtually straight, parallel-sided and smoothly rounded apically, in posterior view ( Fig. 28 ) somewhat club-shaped, apically angular, with few small, sparse setulae in apical ⅓, inner side with small, dense comb of short setulae apically, microtrichia absent, except for few at base; surstyli interconnected via laterally broad processus longi, processus tapering to slender form mesally; cerci simple, somewhat rectangular, tapering basally, rather broad, proportion length/width 2.1, clothed in microtrichia and setulae; phallapodeme rather slender ( Fig. 29 ), anterior arm with smoothly rounded corners, anterior arm clearly longer than posterior arm; ejaculatory apodeme strongly broadening apically, fan-shaped ( Fig. 30 ).

Distribution: Collection records indicate the species to occur in forests of South Africa and Swaziland, at elevations from near sea level to 1000 m.All species in the D. cruciata - group appear to be forest species.

Holotype: ♂ SOUTH AFRICA: KwaZulu­Natal: Pietermaritzburg, Queen Elizabeth Park , 29°33'51"S 30°19'05"E, 930 m, ix.1980, J.J. Feijen ( RMNH).

Paratypes: SOUTH AFRICA: KwaZulu­Natal: 4♂ 5♀ same data as holotype ; 43♂ 61♀ same data but viii– ix.1980 ; 2♂ 3♀ Pietermaritzburg, Town Bush , drying pond, 12.vi.1968, B. Lamoral ; 1♂ 1♀ Pietermaritzburg,

Town Bush, 25 xi.1981, J.G. Londt. Eastern Cape: 1♀ Port St Johns , G. Heinrich. SWAZILAND : 2♂ 5♀ Usutu Forest , 16.iv.1979, G.G.M. Schulten ; 2♂ Usutu Forest , 21.iv.1979, G.G.M. Schulten. (all in RMNH, some paratypes will be deposited to NMSA.)

Figures

Figs 1–4. Head, anterior view (1, 2), wing, dorsal view (3, 4): (1) Diopsis eisentrauti (♀ Togo); (2) D. stuckenbergi sp. n. (♀ paratype, Pietermaritzburg, South Africa); (3) D. eisentrauti (♂ Yaoundé, Cameroon); (4) D. stuckenbergi sp. n. (♂ paratype, Pietermaritzburg, South Africa). Scale bars = 1 mm.

Figs 6–9. Scutum: (6, 7) Diopsis eisentrauti, showing difference in width of transverse pruinose facia in males from Congo (note Laboulbeniales in Fig.6); (8) D.stuckenbergi sp.n.(♂ paratype,Swaziland) showing pruinose T-cross; (9) D. stuckenbergi sp. n. (♀ paratype, Pietermaritzburg, South Africa) lacking central section of T-cross. Scale bars = 0.5 mm.

Figs 14–19. Surstylus, lateral view (14, 15), female sternum 8 (16, 17), sclerotised ring (18, 19): (14) Diopsis eisentrauti (Yaoundé, Cameroon); (15) D. stuckenbergi sp. n. (paratype, Pietermaritzburg, South Africa); (16, 18) D. eisentrauti (holotype, Soppo, Cameroon); (17, 19) D. stuckenbergi sp. n. (paratype, Pietermaritzburg, South Africa). Scale bars = 0.1 mm.

Fig. 23. Diopsis stuckenbergi sp. n., eye span plotted against body length.

Figs 24–27. Diopsis stuckenbergi sp. n. (♀ paratype, Pietermaritzburg, South Africa): (24) postabdomen, ventral view; (25) tergum 10 and cerci, dorsal view; (26) subanal plate; (27) spermathecae. Scale bars = 0.1 mm.

Figs 28–30. Diopsis stuckenbergi sp. n. (♂ paratype, Pietermaritzburg, SouthAfrica):(28) epandrium with surstyli and cerci, posterior view; (29) phallapodeme, lateral view; (30) ejaculatory apodeme and sac. Scale bars = 0.1 mm.